Geology and mineral resources of San Diego County, California
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GEOLOGY AND MINERAL RESOURCES OF SAN DIEGO COUNTY, CALIFORNIA
By F. HAROLD WEBER JR., Geologist California Division of Mines and Geology
With sections on Sand and grave/, and crushed and broken stone, by F. Harold Weber Jr. and Roy M. Kepner Jr.; and Clay, by George B. Cleveland; and Arsenic, and parts of several sections, by R. M. Stewart
COUNTY REPORT 3
California Division of Mines and Geology Ferry Building, San Francisco, 1963
LIBRARY
UNIVERSITY OF CALIFORNIA DAVIS
OF ^
STATE OF CALIFORNIA
EDMUND G. BROWN, Governor
■J? *^>V^
THE RESOURCES AGENCY
HUGO FISHER, Administrator
DEPARTMENT OF CONSERVATION
DeWITT NELSON, Director
DIVISION OF MINES AND GEOLOGY
IAN CAMPBELL, State Geologist
COUNTY REPORT 3 Price $8.00
^
CONTENTS
Page
ABSTRACT 1 i
INTRODUCTION __Z_JZZZZZZZZZZZZZZ 13
Purpose and scope 13
Culture 13
Physical geography __ 1 5
Physical features 1 5
Climate and vegetation 16
Field work 1 7
Acknowledgments 17
GEOLOGIC FEATURES ~ 17
Previous investigations 1 7
Descriptions of the rocks 18
Metamorphic rocks (Cretaceous and/or older) 18
Metasedimentary rocks (Cretaceous and/or older) 18
Metavolcanic rocks (Jurassic and/or Cretaceous) 20
Hypabyssal intrusive rocks associated with the metavolcanic rocks 21
Hybrid gneisses and associated quartz diorite and granodiorite (Cretaceous
and/or older) 21
Intrusive rocks of the batholith of southern California (Cretaceous) 23
, Gabbroic rocks 23
Granitic rocks _. 24
Green Valley tonalite ____ 24
Bonsall tonalite 24
Lakeview Mountain tonalite __ 24
Lake Wolford leucogranodiorite 25
Woodson Mountain granodiorite 25
Indian Mountain leucogranodiorite 25
Escondido Creek leucogranodiorite 25
Roblar leucogranite 25
Other intrusive bodies 25
Pegmatite and aplite dikes 25
Economic significance __ ____ 25
Cretaceous and Tertiary rocks of the San Diego coastal plain region 25
Cretaceous system 25
Tertiary system _ 27
Paleocene rocks 27
Eocene rocks 27
Sandstone undivided (includes Delmar and Torrey sand members of
La Jolla formation) 28
Rose Canyon shale (upper member La Jolla formation) 29
Poway conglomerate __ 29
Intrusive dacite and latite of Eocene age or younger 30
Miocene rocks 30
San Onofre breccia 30
Monterey shale 30
Miocene-Pliocene rocks __ 30
Capistrano formation 30
Pliocene rocks undivided _ 30
Tertiary and older Quaternary rocks of the Salton Basin 32
Tertiary system _ 32
Miocene rocks — 32
Split Mountain formation 32
Alverson andesite lava and associated pyroclastic and sedimentary rocks 32
Fish Creek gypsum 32
Miocene-Pliocene rocks ~ — 32
Imperial formation 32
Canebrake conglomerate _ 32
Truckhaven rhyolite — 32
Pliocene rocks - 32
Palm Spring formation — 32
Borrego formation — - 32
M
CONTENTS-Continued
Page
GEOLOGIC FEATURES— Continued Descriptions of the rocks — Continued
Tertiary and older Quaternary rocks of the Salton Basin — Continued
Upper Tertiary and lower Quaternary systems undivided _ 33
Pliocene-Pleistocene rocks 33
Ocotillo conglomerate 33
Brawley formation 33
Quaternary rocks of the coastal plain and Peninsular Range province, and
younger Quaternary rocks of the Salton Basin 33
Quaternary system _ 33
Pleistocene rocks 33
Basa Itic flows 33
Terrace deposits and dissected alluvium 33
Landslide deposits 33
Lakebed deposits . 33
Recent rocks . 33
Playa deposits 33
Alluvium 33
Structural geology .. 35
Marine geology 35
MINERAL RESOURCES AND MINING _ 36
History of mining 36
Mineral production _ 42
Land ownership and entry 43
Land open to prospecting and location of mining claims 44
Land possibly open to prospecting by permit, but closed to location of claims 45
Indian reservations _ 45
State lands 46
State-owned lands 46
Anza-Borrego Desert State Park 46
Privately owned land 46
Land closed to prospecting and mining 46
City and county zoning 46
Water for mining operations 47
Previous descriptions of mineral deposits 47
Mineral commodities and descriptions of mineral deposits 47
Abrasives . 48
Agricultural minerals and soil amendments 48
Aluminum minerals 49
Antimony _. 49
Arsenic, by Richard M. Stewart 49
Black Mountain group 49
Asbestos — 50
Beryllium _ 50
Ruby group 51
Bismuth 51
Boron 51
Bromine 52
Calcite (optical grade) 52
Hilton deposit 52
Cesium 54
Clay, by George B. Cleveland 54
Kelley Ranch mine 57
Linda Vista mine ... 58
Pacific Clay Products Company (Kelley No. 1) mine 59
Standard Oil Company (Filtrol) mine 60
Union Brick Company mine, East pit (Union Brick and Tile Company) 61
Vitrified Products Company mine (Vitrified Clay Products Co., Wiro mines) 68
Coal - 68
Cobalt 68
Columbium-tantalum 68
Copper, by F. H. Weber and R. M. Stewart 68
Daley (Barona) mine _ 69
Encinitas (Danes Lea) mine _ 69
[4]
CONTENTS-Continued
Page
MINERAL RESOURCES AND MINING— Continued
Mineral commodities and descriptions of mineral deposits — Continued
Cornwa 1 1 stone 72
Diatomite 72
Dumortierite 72
Feldspar _. 72
Buckthorn (Flynt Silica and Spar Company, State Lease) deposit 73
McGinty Mountain (Dehesa Cornwall Stone) deposit 75
Pacific mine (Arthur Clay Spar Number One, Campo, Pacific Sanitary
Porcelain Co., Standard Sanitary, Stell) 76
Quality (Orion, Osborne) deposit 84
Fluorine minerals ._ 84
Gem minerals 84
Gem-bearing pegmatite deposits 84
Distribution and general features 84
Summaries of districts 86
Pala district 86
Mesa Grande district __ _ 87
Ramona district 87
Rincon district 87
Other areas L 87
Miscellaneous gem and ornamental minerals and rocks 87
Agate and jasper 87
Axinite 87
Dumortierite — _ 87
Epidote __.. 87
Garnet 87
Feldspar 87
Jade 88
Orbicular gabbro 88
Rhodonite .__. 88
Markets 88
A.B.C. mine (Daggett group) 88
Blue Bell deposit (Blue Tourmaline claim, San Diego group) 89
Esmera Ida mine 89
Himalaya mine 91
Katerina (Ashley, Caterina, Catherina, Katrina) mine 92
Little Three mine . 92
Pala Chief mine 95
San Diego mine 96
Surprise mine 96
Tourmaline King (Schuyler, Wilke) mine _ 97
Tourmaline Queen mine 97
Gold 115
District summaries 116
Julian district 1 16
Escondido region 1 20
Mesa Grande district 121
Area south of Pine Valley 121
El Cajon district 121
Laguna Mountains region 121
Boulder Creek (Mineral Hill) district 122
Deer Park district 122
Dulzura district 1 22
Montezuma (Rice) district 122
Ballena placer deposits 122
Additional gold mines 122
Boulder Creek group (Boulder Creek mines, Mineral Hill mine) _ 123
Cleveland-Pacific (Escondido) mine _._. 123
Donohoe (Artery Consolidated, Comet, Donohue, Golden Artery) mine 123
Golden Chariot mine _ 124
Golden Gem group (Big Blue, Blue Hill, Gardiner, Gardner, Gem mine) 126
Helvetia mine 1 28
[5l
CONTENTS-Continued
Page
MINERAL RESOURCES AND MINING— Continued
Mineral commodities and descriptions of mineral deposits — Continued Gold — Continued
Madden group (Antelope mine) 130
Noble group (Noble mines, Noble's mines, Pine Valley mines) ___. 130
Owens (Old Owens, New Owens) mine 131
Ranchito mine 1 32
Ready Relief group (Bailey Brothers mine) 132
Stonewall (Stonewall Jackson) mine 133
Warlock group 1 35
Granite 167
Graphite ___ 167
Gypsum 167
Iron, by R. M. Stewart and F. H. Weber 171
Kyanite, andalusite, sillimanite, dumortierite, and topaz 171
Dehesa dumortierite deposit 171
Lead 173
Limestone and dolomite 173
Geologic occurrence 1 73
Possible uses 1 74
Elliot deposit 1 74
Golden State (Dos Cabezas marble placer) deposit ____ 175
Heathman (Dos Cabezas, Heathman quarry, Mamie-Heathman) deposit 177
Jamul Ranch (Jamul Portland Cement Co.) deposit ____ 179
Verruga (Verruga marble) deposit 181
White Cap (Blockman) deposit 181
Lithium compounds 1 85
Stewart mine (American Lithia Company) 185
Magnesium compounds 1 89
Mineral Products Division (California Chemical Corporation, Westvaco
Chemical Division, Westvaco Chlorine Products Corporation) 189
Manganese 190
Mica 190
Mica Gem group 190
Mineral fillers 1 93
Mineral paint 1 93
Molybdenum __. ____ 193
Bour deposit (Molybdenum Syndicate Limited, Santa Maria Mining and
Milling Company) ___ 1 94
Dillbeck deposit _.__ 1 95
Lippner (Aiken, Aitken, Campo Molybdenum mines [Midway]) deposit 197
Nickel ___ 198
Friday deposit 1 98
Orbicular gabbro 201
Peat 201
San Luis Rey deposit _• 201
Perlite 202
Petroleum and natural gas .-. 202
Phosphates 202
Potash 203
Pyrites 203
Pyrophyllite ._._ 203
Four-Gee (Golem) deposit 203
Harris deposit 204
Palagonite deposit 206
Pioneer deposit 206
Quartz (including quartz crystal) and quartzite _.__ 208
Inner zones of pegmatite deposits 208
Massive quartz bodies (including veins) 209
Bedded quartz-feldspar sand 209
Beach and dune sands __ 210
Quartzite 210
Lowrey deposit 21 1
[6]
CONTENTS-Continued
Page MINERAL RESOURCES AND MINING— Continued
Mineral commodities and descriptions of mineral deposits — Continued Quartz — Continued
Rose Quartz mine ___ 211
Round Potrero deposit - 211
White Butte deposit (American Encaustic Tiling Company) 217
Rare earth elements - 217
Saline minerals ... 217
Sa It 2 1 7
Western Salt Company _ 218
Sand and gravel, and crushed and broken stone, by F. H. Weber and
Roy M. Kepner Jr. 221
Sources of material, and methods of mining and treatment 223
Sand and gravel 223
Poway conglomerate and alluvium and terrace deposits derived from
the Poway conglomerate 223
River and stream bed deposits 228
San Onofre breccia 229
Sandstone of Eocene age 230
Beach deposits 230
Crushed and broken stone - 230
Gra nitic rocks - - 230
Meta volcanic rocks 231
Volcanic rocks of Tertiary age 232
Crystalline limestone and dolomite 232
Shale of Tertiary age - 232
Gabbroic rocks 232
Pegmatite deposits 232
Dumortierite-bearing rock 232
Products and marketing 232
Aggregate 233
Riprap _ 233
Fill material 252
Road base 252
Roofing granules 252
Decorative (ornamental, garden) stone 252
Poultry grit _____ 252
Drain rock ____ 252
Reserves ____ __ 252
Sands, specialty _ 252
Crystal Silica Company (Crystal Silica Sand Company) 253
Shale, expansible 255
Silver 255
Stone, dimension 255
Granite — 255
Geology of the deposits 255
Quarrying and preparation of stone 258
Uses, markets and prices __ 258
Summaries of areas 258
Lakeside-Foster-Santee area (gray granite) 258
Escondido area (black granite) __ 260
Vista area (black granite) 260
Pala area (black granite) ___ 260
La Cresta area (gray granite) 261
Bernardo area (black granite) 261
Grossmont-La Mesa area (gray granite) 261
Marble 261
Quartzite 261
Escondido Quarries, Inc. (Pacific Cut Stone and Granite Co.) 261
National Quarries (Johnson Brothers) ___ ___ 261
Red Rose quarry ____ ._ 261
Strontium 268
Roberts and Peeler (Peeler and Roberts, Roberts Celestite) deposit 268
[7]
CONTENTS-Continued
Page
MINERAL RESOURCES AND MINING— Continued
Mineral commodities and descriptions of mineral deposits — Continued
Tin .. 270
Tungsten 270
Metal Mountain mine __ 272
Pawnee (Carr, Oak Grove) mine 273
Sundown mine 274
Uranium and Thorium __ 280
Vanadium 280
Vermiculite _ 280
Circle group deposit 280
Volcanic ash 282
Wollastonite __ 283
Zinc .... 283
Zirconium 283
ANNOTATED BIBLIOGRAPHIES 283
Collective bibliography 283
Subject bibliographies _._ __ 295
Mineral resources and mining (except pegmatites and petroleum) 295
Pegmatites 300
Petroleum geology 302
Areal, general, and structural geology 303
Igneous and metamorphic rocks 305
Stratigraphy, paleontology, and geomorphology __ 306
Water resources, soils, and engineering geology __ 308
Marine geology 309
ILLUSTRATIONS
PLATES
Plate 1. Map of San Diego County showing areal geology and mineral deposits In pocket
Plate 2. Map of San Diego County showing topographic map coverage and geologic mapping
adapted for plate 1 — — _ In pocket
Plate 3. Geology and mineral deposits of the Pala district, San Diego County In pocket
Plate 4. Principal mines of the Mesa Grande gem mining district, San Diego County In pocket
Plate 5. Geology and gem mineral deposits of the principal part of the Ramona district,
San Diego County In pocket
Plate 6. Geologic map of the Rincon district showing mines and prospects, San Diego County In pocket
Plate 7. Geology and mineral deposits of the Julian district, San Diego County In pocket
Plate 8. Map of underground workings of the Eagle and High Peak mines, showing geology
and typical vein system of the Julian district, San Diego County In pocket
Plate 9. Map of Julian and vicinity showing location of mining claims, San Diego County In pocket
Plate 10. Granite quarries in the Lakeside-Foster, Escondido, and Vista areas, San Diego
County In pocket
Plate 11. Status of ownership and administration of land in San Diego County .. In pocket
FIGURES
Page Figure 1. Index map showing San Diego County and railroad network of most of southern
California — .. 13
Figure 2. Geologic sketch of road cut shown in photo 11- 26
Figure 3. Graph comparing yearly value of mineral production of San Diego County with growth
in population, 1910 to 1957 __ _.. 38
Figure 4. Graph showing relationship between yearly production of sand and gravel in San Diego
County and growth of population 39
Figure 5. Map showing first coverage of San Diego County by topographic maps of the U.S.
Geological Survey _. 44
Figure 6. Map showing location of U.S. mineral monument in San Diego County 45
Figure 7. Map showing distribution of workings in Hilton deposit 53
Figure 8. Geologic sketch map, Kelley Ranch mine ._ 57
Figure 9. Geologic sketch map, Linda Vista mine 58
Figure 10. Geologic sketch map, Pacific Clay Products mine, East pit 59
Figure 11. Geologic sketch map, Pacific Clay Products mine, West pit _ — 59
Figure 12. Geologic sketch map, Union Brick Company mine. North pit 61
Figure 13. Geologic sketch map, Union Brick Company mine, East pit _ 62
Figure 14. Geologic sketch map. Vitrified Products Co. mine 68
Figure 15. Map showing Laguna Junction and vicinity, and location of feldspar- and quartz-bearing
pegmatite deposits _ 73
Figure 16. Map showing patented claim that covers the Pacific feldspar deposit 76
Figure 17. Geologic section through pegmatite body at Pacific feldspar mine __ 77
Figure 18. Plans of underground workings, Pacific mine 78
[8]
CONTENTS-Continued
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FIGURES— Continued
Page
Map showing patented claims on Quality pegmatite deposit 84
Idealized sections of pegmatite dikes in Pala district 85
Map of Esmeralda claim, Mesa Grande district 89
Map showing claims comprising Himalaya mine — 91
Map showing approximate location of mining claims, Pala district, and limits of Pala
Indian Reservation — 93
Geologic map of Chieftain mine, Julian district _. 118
Geologic map of Hidden Treasure mine, Julian district 118
Idealized diagram of roll structure of quartz-bearing veins, Julian district 119
Pyrrhotite and gold in banded quartz from Golden Chariot mine 119
Geologic map of Jumper mine, Julian district 120
Map showing sites of Cleveland-Pacific, Oro Fino, and Cravath gold mines near Escondido 120
Map of part of Boulder Creek district 121
Map showing patented claims of Donohoe gold mine 124
Longitudinal section through Golden Chariot gold mine 125
Map of Golden Gem group of claims, Julian district 127
Geologic plan of Lane tunnel, Golden Gem group, Julian district 128
Longitudinal section through the Helvetia mine, Julian district _. 129
Map showing Noble group of claims, Laguna Mountains. _ 131
Longitudinal section through the Stonewall mine 133
Sketch of Dehesa dumortierite deposit 171
Map showing Sentenac patented claim near Ranchita 174
Map showing unpatented holdings covering Elliot dolomite deposit, Coyote Mountains — 174 Map showing patented claims covering part of Golden State crystalline limestone deposit
near Dos Cabezas 1 75
Generalized geologic map of Dos Cabezas area 176
Geologic sketch map and cross section of Jamul Ranch limestone deposit 179
Plan of surface and underground workings, Stewart mine 186
Geologic section through the Stewart mine 187
Map showing location of Bour molybdenite deposit near Ramona ... 194
Geologic sketch map of Bour molybdenite deposit 194
Map showing Dillbeck and Lippner molybdenite deposits, Campo 195
Sketch showing grains of molybdenite in aplite at Dillbeck deposit, Campo 197
Geologic map and sections of Friday deposit, near Julian 199
Geologic map of the San Dieguito pyrophyllite area _ 205
Map showing patented claims and workings on Palagonite pyrophyllite deposit near
Rancho Santa Fe .._ 206
Map of Jewel Valley and vicinity, showing location of quartz and quartz-bearing deposits 210 Geologic sketch map and cross section of the White Butte pegmatite deposit, Jewel
Valley area 212
Map showing Western Salt Company evaporating ponds at south end of San Diego Bay 219
Flow sheet of Mission Valley operation of Caudell and Johnson 226
Flow sheet of Murray Canyon operation of H. G. Fenton Material Company... 227
Flow sheet of Woodward Sand Plant, Mission Valley 229
Geologic map of the celestite deposit near Ocotillo 269
Map of Pawnee mine, San Diego and Riverside Counties 274
PHOTOS
General view of part of coastal plain province .._ 14
El Cajon Mountain _ 15
General view of Vallecito Valley region 16
General view of part of escarpment on west side of Borrego Valley 16
General view of west side of San Jose Valley ._ 16
General view of part of Carrizo Canyon, in Jacumba Mountains 19
General view of rocks on part of south side of Oriflamme Mountains 20
Roadcul near Julian showing contact between "hybrid rocks" and schist 22
General view of Oriflamme Mountains region and part of Julian district 22
Roadcut near Descanso showing granitic rocks 24
Roadcut in Palomar Mountain region showing granitic rocks, structures, and pegmatite
dikes - - 26
General view of sea coast at La Jollo and sea cliffs of sandstone of Cretaceous age 27
General view of Torrey Pines area showing relationships between Linda Vista terrace
deposits, Rose Canyon shale, and Torrey sand 28
Roadcut in Torrey Pines Park showing Torrey sand and Linda Vista terrace deposits 28
General view of Foster area and relationships between Poway conglomerate and under- lying granitic rocks 29
Closeup of San Onofre breccia at deposit of H.W. Rohl Company, Oceanside 30
General view of volcanic rocks overlying granitic rocks, Table Mountain, near Jacumba 31
Geology of part of Table Mountain 31
Closeup of Earthslide deposits in roadcut on Nigger grade, near Pauma Valley 33
Aerial view, Julian district and vicinity 34
General view of Banner Canyon area, Julian district, and Elslnore fault 34
General view of west slope of Palomar Mountain, along trace of Elsinore fault 35
Yard of Union Brick Company, Rose Canyon __ 37
General view of Hilton optical calcite deposit _ 54
Kilns of Union Brick Company, Rose Canyon 56
[9]
CONTENTS-Continued
PHOTOS— Continued
Page
Photo 26. General view of workings of Standard Oil Company bentonite mine, Otay Valley 56
Photo 27. Linda Vista clay mine— 58
Photo 28. General view of the Union Brick Company operations, Rose Canyon 62
Photo 29. Buckthorn feldspar deposit near Live Oak Springs 74
Photo 30. North wall of glory hole in Buckthorn deposit 74
Photo 31. South part of McGinty Mountain silicified alaskite deposit 75
Photo 32. Pacific Mill, Cameron Corners — 76
Photo 33. General view of Pacific deposit — 77
Photo 34. Aerial view of part of Mesa Grande district .. .. 90
Photo 35. General view of Little Three gem mine and vicinity, Ramona district 94
Photo 36. Workings and pegmatite deposit of Little Three gem mine, Ramona district 94
Photo 37. Workings of Pala Chief gem mine, and part of the pegmatite deposit of the Tourmaline
Queen mine - - - — - 95
Photo 38. Gold King mill, Julian - 117
Photo 39. Part of underground workings, Golden Chariot mine 125
Photo 40. General view of Golden Chariot mine area about 1900 126
Photo 41. Helvetia mine area, Julian district, about 1901 129
Photo 42. Ranchito gold mine and mill about 1895 132
Photo 43. Stonewall mine about 1900 - 134
Photo 44. Stonewall mine about 1900 134
Photo 45. Dehesa dumortierite deposit near Alpine 171
Photo 46. Oblique aerial view of Dos Cabezas limestone deposits and vicinity 173
Photo 47. Elliot dolomite deposit 175
Photo 48. Golden State limestone deposit near Dos Cabezas 177
Photo 49. Limestone milling equipment and Heathman limestone deposit at Dos Cabezas 178
Photo 50. Principal quarry in Heathman limestone deposit, Dos Cabezas 178
Photo 51. Part of Jamul Ranch limestone deposit 180
Photo 52. Remains of Jamul Portland Cement Company kilns, 1957 180
Photo 53. Part of Verruga limestone deposit near Ranchita 181
Photo 54. View of Stewart dike showing Stewart lithium mine, Pala district.. 188
Photo 55. General view of plant of Mineral Products Division at which magnesium compounds are
produced 189
Photo 56. Manganese oxides in quartzite at locality near Jacumba 190
Photo 57. Four-Gee pyrophyllite deposit near Rancho Santa Fe 204
Photo 58. Part of Harris pyrophyllite deposit near Rancho Santa Fe 205
Photo 59. General view of Pioneer pyrophyllite deposit near Rancho Santa Fe 207
Photo 60. General view of Walker quartz deposit, Jewel Valley area 209
Photo 61. Aerial view of Western Salt Company operations 218
Photo 62. General view of part of operation of Western Salt Company, Chula Vista 220
Photo 63. Mill area of Western Salt Company, Chula Vista .. 221
Photo 64. Exposure of Poway conglomerate at Murray Canyon operation of H. G. Fenton Material
Company 222
Photo 65. Closeup of Poway conglomerate at Murray Canyon operation of H. G. Fenton Material
Company 222
Photo 66. General view of Carroll Canyon operation of H. G. Fenton Material Company 222
Photo 67. Closeup of alluvium derived from Poway conglomerate at Carroll Canyon operation of
H. G. Fenton Material Company 222
Photo 68. Mining at Murray Canyon operation of H. G. Fenton Material Company 224
Photo 69. General view of part of Mission Valley operation of Caudell and Johnson 224
Photo 70. Hydraulic washing at Mission Valley operation of H. G. Fenton Material Company 225
Photo 71. Mission Valley plant of Caudell and Johnson 225
Photo 72. Plant of Murray Canyon operation of H. G. Fenton Material Company 227
Photo 73. General view of H. W. Rohl Company operation, Oceanside 228
Photo 74. General view of decomposed granite operation of San Diego Cement Company, Jamacha
Junction ..: 230
Photo 75. General view of Canyon Rock Company operation of V. R. Dennis 231
Photo 76. Part of specialty sands operation of Crystal Silica Company, Oceanside... _ 253
Photo 77. General view of Crystal Silica Company operation, Oceanside 254
Photo 78. Residual boulders of gabbro (black granite) at deposit near Vista 256
Photo 79. General view of adjacent operations of National Quarries, Inc. and California Wire
Sawyer Corporation, at Foster 256
Photo 80. Cutting a block of black granite into slabs at Escondido Quarries, Inc — . 257
Photo 81. Polishing slab of black granite at Escondido Quarries, Inc 257
Photo 82. Quarrying residual boulders of gabbro (black granite) at Escondido Quarries, Inc 259
Photo 83. One of the black granite quarries in Gopher Canyon owned by Pomona Granite Co 260
Photo 84. Part of Roberts and Peeler celestite deposit 268
Photo 85. General view of part of Metal Mountain tungsten deposits near Live Oak Springs.— 273
Photo 86. General view of Beauty Mountain and Pawnee tungsten mine northeast of Oak Grove .... 274
Photo 87. Aerial oblique view of Pawnee mine area 275
Photo 88. General view of part of Circle group vermiculite deposit northeast of Jacumba 282
Photo 89. Main workings of Circle group deposit 282
TABLES
Table 1. Recorded mineral production of San Diego County from 1880 through 1959. 40
Table 2. California industrial clays _ 55
Table 3. Chemical analyses of Otay bentonite.. 61
[io]
ABSTRACT
San Diego County, which comprises 4,258 square miles, is the most southwesterly county in the continental United States. The county is almost square in shape. It contains three northwest-trending geomorphic provinces, which from west to east are: (1) a narrow coastal plain; (2) a broad, interior upland of ranges (as high as 6,500 feet in elevation) and intermediate valleys (Peninsular Range province); and (3) part of the western edge of the Salton (Imperial) Basin, which constitutes a desert.
The oldest rocks in the county are mildly to moderately metamorphosed sedimentary rocks which consist mainly of inclusions, pendants and screens of quartz-biotite schist and gneiss. These rocks, which are widespread in the county, have been dated as Triassic, but some may be as old as Precambrian and others may be as young as Cretaceous. Metavolcanic rocks, of possible Jurassic or Cretaceous age, are exposed in a belt along the west edge of the interior upland province. These rocks are commonly andesitic flows. The interior upland province is underlain largely by intrusive rocks of the batholith of Southern California. These rocks consist of individually intruded bodies which most commonly are tonalite (quartz diorite), and less commonly are granodiorite, gabbro, or granite. The batholith is Cretaceous in age. Hybrid gneisses and associated granodiorite and quartz diorite occur in the central part of the county. Pegmatite dikes cut most of the rocks described above.
The post-batholith rocks of the coastal plain are mainly clastic, marine sedimentary deposits which overlie the older rocks and most commonly dip gently toward the west and southwest. These rocks range in age from Cretaceous to Quaternary and consist chiefly of beds of sandstone, shale and conglomerate. Two small bodies of volcanic rocks cut Eocene sedimentary rocks. The post-batholith rocks of the Salton Basin region range in age from Miocene to Pleistocene and consist mainly of clastic, marine and nonmarine sedimentary rocks which are composed chiefly of fanglomerate, conglomerate, sandstone and breccia. Volcanic flow rocks occur in the southeast part of the county. Within the interior upland province are landslide deposits, dissected alluvium, and lake bed deposits. Playa deposits of Recent age occur in the Salton Basin region, and undissected alluvial deposits of Recent age are abundant throughout the county. The most prominent structural features of the county are numerous, extensive, northwest- trending faults, the principal one of which is the Elsinore Fault.
The total value of the mineral production of San Diego County from 1870 through 1959 is estimated to be about $125,000,000. Of this value, slightly more than $75,000,000 was recorded from the end of World War II through 1959. The value of the recorded mineral production for 1959 is $14,489,600. The tremendous growth in population of the county since the end of World War II, and the consequent growth of the building industry, resulted by 1959 in a nearly seven-fold increase in the production of sand and gravel, and crushed and broken stone. In 1959 these com- modities accounted for about 94 percent of the value of minerals produced. Processed sand and gravel are produced mainly in the San Diego region, from river bed deposits of Recent age, and the Poway conglomerate of Eocene age, and are used chiefly as concrete aggregate. Crushed stone, which includes decomposed granite, is produced from granitic and metavolcanic rocks, and is used principally as road base, fill, and concrete aggregate. Broken stone, which is quarried from metavolcanic and granitic rocks, is used almost entirely as riprap.
Since the early 1900's other nonmetallic minerals also have risen to importance. Metallic commodities, on the other hand, have been mined mostly during national emergencies. Dimension stone has been produced in the county since 1898, now mainly from granitic rocks near Foster, and from gabbroic rocks near Escondido and Vista. It is used as surface plates, and as building and monument stone. One operator pro- duces dimension stone from quartzite. Salt has been produced since 1869 along the edge of San Diego Bay by evaporating sea water, and now is produced by one operator. Sea water bittern retained from this operation is utilized by another company to produce magnesium chloride. Common clay from the Rose Canyon shale, of Eocene age, is utilized in the manufacture of bricks. Clay for other ceramic uses is mined from
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deposits of probable Paleocene age. Bentonitic clay mined formerly in the Otay area was used as an absorbent in petroleum refining. A single company produces specialty sands from sandstone of Eocene age at a locality in Oceanside. Pyrophyllite for use as an insecticide carrier has been mined since 1946 from altered metavolcanic rocks near Rancho Santa Fe.
Gem minerals, including tourmaline, spodumene variety kunzite, topaz, garnet, and quartz, have been mined from pegmatite deposits since the late 1890's, but mainly between 1900 and 1912. The principal gem mines are in the Pala and Mesa Grande districts. Small tonnages of common quartz have been mined intermittently for various uses. Small quantities of celestite (strontium sulfate) are mined occasionally from a single deposit in the county. Limestone and dolomite produced intermittently from crystalline metasedimentary rocks, mainly in the southeast part of the county, are used chiefly as roofing granules.
Nonmetallic minerals that have been produced in the county in the past, but which were not produced in the middle or late 1950's, include potash (World War I); pebbles for grinding and filtering (1915-1949); bromine (1926-1945); feldspar (1918-1943), of which the Pacific deposit once was the principal source in the State; lithium mica (lepidolite), obtained mainly from the Stewart deposit (1892-1928); optical calcite (World War II); peat (late 1940's); quartz crystal (electronic and fusing grade); and vermiculite. Unmined deposits of the following nonmetallic minerals occur in the county: graphite, gypsum, dumortierite-sillimanite, mica, expansible shale, volcanic ash, and wollastonite. Petroleum has been explored for unsuccessfully in the coastal area and at one locality on the eastern edge of the county.
The principal metallic commodities that have been mined in the county are gold, tungsten and copper, but the value of production of these is relatively small. Gold has been mined intermittently in the county since about 1870, but mainly from 1870 to 1875 and from the late 1880's to 1900. The value of the total production is estimated to be between $5Vi and $6 million. Although many deposits have been worked, most of the gold mined came from quartz vein deposits in the Julian district and from the Stonewall deposit. Tungsten has been mined from several tactite and quartz vein deposits in the county, during World War II and during the early and mid 1950's. Copper has been mined from two deposits, chiefly during World War I. Very small quantities of molyb- denite and silver also have been produced. Small, unmined, and/or low grade metallic deposits include those of nickel-cobalt-copper, arsenic, beryllium, iron, lead, manganese, and uranium-thorium.
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GEOLOGY AND MINERAL RESOURCES OF SAN DIEGO COUNTY, CALIFORNIA*
By F. HAROLD WEBER, JR.
INTRODUCTION
PURPOSE AND SCOPE
One of the functions of the California Division of Mines and Geology is the publication of reports that contain reviews of the mineral resources and mineral industries of the counties of California, with emphasis on descriptions of individual mineral deposits. Reports of this type on San Diego County have been published by the division (and its predecessor, the California Mining Bureau) in 1888, 1914, 1925, and 1939; and descriptions of from one to several deposits have been given in many other reports.
The present report contains discussions of the individ- ual mineral commodities of the county, with each dis- cussion followed by descriptions of deposits pertinent to that commodity. Descriptions of more than 500 deposits are given, either within the text or in tabulated lists.
Also included in the report are reviews of the history of mining and the mineral production, and discussions of the problems of land entry and water for mining. Pre- ceding the section on mineral commodities is a review of the geologic features of the county, with emphasis on descriptions of rocks. A comprehensive bibliography on geology and mineral deposits also is provided. The lo- cations of the mineral deposits and the geologic features of the county are shown on a map that accompanies the report.
CULTURE
San Diego County, the most southwesterly county in the continental United States, is bounded on the west by the Pacific Ocean, on the north by Orange and Riverside Counties, on the east by Imperial County, and on the south by Baja California, Mexico (Fig. 1). It is cut by meridian 117°00' and parallel 33°00'.
Manuscript submitted September 1959 for publication, and partially supplemented by additional data through June 1961.
Figure 1. Index map showing San Diego County and railroad network of most of southern California.
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The county was one of the original 27 created in 1850, when California became a state. It was named after San Diego Bay, and vicinity, which had been christened first by Cabrillo in 1542 as San Miguel Bay, then rechristened San Diego Bay by Viscaino on November 12, 1602. No- vember 12 was the birthday of the patron saint of his flagship— San Diego de Alcala. Originally the county was one of the two largest in the State, and included all of California east of a line of longitude between 11 7° 15' and 117°30'. Its size was diminished as additional coun- ties were formed in Central and Southern California, and its present size and shape was established with the forma- tion of Riverside County in 1893 and Imperial County in 1907.
San Diego County is roughly rectangular in shape. Its maximum east-west dimension is about 88 miles; its maxi- mum north-south dimension is about 63 miles; and its coastline is about 70 miles long. The county comprises 4,258 square miles (2,725,120 acres).
The County and City of San Diego have shown a remarkable growth since World War II, mainly because of an increase in defense activities, and industries asso- ciated with defense, and because of the mild climate of the coastal region, which has attracted new residents. In 1940 the population of the county was about 289,000, and by 1960 it had risen to about 1,033,000. Most of the residents live in the city and suburbs of San Diego, which are in the southwest corner of the county, near San Diego and Mission Bays. By 1960 the population of the
City of San Diego was roughly 573,000. Most of the remaining residents of the county live along the coast, north of San Diego, and in inland communities adjacent to the coast. Only a very small part of the population lives more than 20 miles inland from the ocean. The most important fields of employment in the San Diego region are the U.S. Navy, the aircraft industry, tourism, and related industries and businesses. The major port is San Diego and the major airport also is at San Diego. The county is served by two railroads and three United States highways. A line of the Atchison, Topeka and Santa Fe Railroad extends from Los Angeles, along the coast, to San Diego, with branch lines in the county serving Fallbrook and Escondido (see Fig. 1 or PI. 1). The San Diego and Arizona Eastern Railroad (now a division of Southern Pacific) runs from San Diego east- ward to El Centro in Imperial County, via Chula Vista, Tijuana (in Mexico), Campo and Jacumba. A branch of this road extends from San Diego to El Cajon. The three United States highways extend outward from the City of San Diego. These are: U.S. 101, which skirts the coast of the Pacific Coast states; U.S. 395, which extends northward from San Diego, via Escondido to Riverside in Riverside County, San Bernardino in San Bernardino County, and beyond; and U.S. 80, which runs eastward from San Diego, via El Cajon, Jacumba, and El Centro, to the southeastern United States. The paved roads of the State of California and paved and unpaved roads of the County of San Diego link all communities within the
Photo 1. View east toward coastal plain province from top of Torrey Pines grade, U.S. Highway 101. Dissected Linda Vista terrace is underl by Torrey sand of Eocene age (white exposures on left) and Rose Canyon shale of Eocene age (dark, subdued exposures on right). Foothills Peninsular Range province border coastal plain on east (far background). Mountains of the Peninsular Range province underlie skyline.
am of
Black Mt. Linda Vista Meso
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San Diego— Introduction
15
Photo 2. View north toward El Cajon Mountain (3,675 feet), which is about 7 miles northeast of Lakeside. Difference in elevation between top of mountain and San Diego River valley is 3,125 feet. Mountain consists of striking exposure of Woodson Mountain (?) granodiorite which is bor- dered on south and east by Green Valley (?) tonalite. Quarry on side of mountain was source of broken stone used in construction of El Capitan dam, about a mile to the southeast.
county and connect the border communities with points outside the county. In addition, the United States Forest Service, the State of California, and the County of San Diego maintain a network of unpaved firetruck roads (or trails) for which public use is limited, especially during fire season. All federal, state, and county roads are shown on Plate 1.
PHYSICAL GEOGRAPHY PHYSICAL FEATURES
San Diego County includes parts of three northwest- trending natural provinces, which from west to east are the coastal plain of southern California, the interior up- land of ranges and valleys (Peninsular Range province), and the Salton (Imperial) Basin, which includes the Colorado Desert.
Coastal Flain. The coastal plain of San Diego County ranges in width from less than one mile at the north boundary of the county to about 1 2 miles at the south boundary. The province is composed of dissected, mesa- like terraces which grade inland into rolling hills com- monly topped by remnants of terraces. This terrain is underlain by nearly flat-lying sedimentarv rocks com- posed mainly of beds of sandstone, shale and conglom- erate (see section herein on "Geologic Features"). The elevations of most of the terraces lie within the range of 300 to 500 feet (Fllis and Lee, 1919). The most extensive of them are in the San Diego region, and these have been named the Poway, Linda Vista (Photo 1), and Otay terraces (or mesas). Rolling hills characterize the inland region between Oceanside and Del Mar (Photo 77), and the area east and northeast of Chula Vista. The province is dissected by intermittent rivers and streams which flow westward and southw estw ard. The most prominent
rivers are, from north to south, the Santa Margarita, San Luis Rey, San Diego, Sweetwater, Otay, and Tia Juana (see PI. 1). Tidal marshes are common at the mouths of the rivers.
The coastline is curved westward very gently from the north boundary of the county southward to La Jolla Peninsula. The south part of the coastline is broken by La Jolla and Point Loma Peninsulas, which are sepa- rated by Mission (False) Bay. San Diego Bay is on the southeast side of Point Loma Peninsula. The coastal plain is bounded on the east by the foothills of the in- terior upland province.
Interior Upland of Ranges and Intermediate Valleys (Peninsular Range Province). By far the largest part of San Diego County consists of the interior upland (Pen- insular Range) province which is bordered on the west by the coastal plain and on the east by the Salton Basin. The province is composed of ranges of steep-sloped hills and mountains separated by intermediate valleys which are generally of small extent. Most of the slopes that are underlain by granitic rocks are boulder-covered (Photo 10), and some mountains and ranges underlain by these rocks are almost ledge-like (Photo 2). Terrain under- lain by metamorphic rocks is subdued in the moist, coastal areas, but more resistant in the drier, inland areas. Metavolcanic rocks along the coast comprise re- sistant hills and mountains (see section herein on "Geo- logic Features").
The province ranges in elevation from points slightly less than 1,000 feet on the west side to mountain tops slightly more than 6,500 feet on the east side. The high- est part of the province consists of a belt of mountains and mountain ranges which extends southeastward from the Riverside County line, near Pala, to Jacumba. These include (from northwest to southeast) the Agua Tibia Mountains, Palomar Mountain (6,138 feet), San Ysidro Mountain (6,147 feet), Volcan Mountain (5,700 feet), Hot Springs Mountain (6,533 feet) and vicinity, Cuya- maca Peaks (including Cuyamaca Peak, 6,375 feet), and the Oriflamme (Photo 9), Vallecito, Tierra Blanca, In-ko-Pah and Jacumba Mountains (Photo 6). The higher ranges in the northwest part of the province are the Santa Margarita, San Marcos, and Merriam Mountains, in the southwest part are the San Ysidro and San Miguel Mountains, and in the northeast part are the Santa Rosa Mountains. High plateaus or mesas, such as Julian and La Cresta-Suncrest mesas, are common in higher parts of the province. Very steep slopes are common in the south-central and eastern parts of the province. Espe- cially steep are the west slopes of Palomar Mountain (Photo 22) and the Santa Rosa Mountains, and the east slopes of the Laguna Mountains (Photo 3), and the mountains on the west side of Borrego Valley (Photo 4). Major valleys in the province are San Jose (Photo 5), San Felipe, Earthquake, Vallecito, and Jacumba. The major drainage to the west ts via the San Luis Rev, San Dieguito, and San Diego Rivers and tributaries, and by Cottonwood Creek (which flows into the Tia Juana
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California Division of Mines and Geology
[County Report 3
"-
Photo 3. Laguna Mountains. View northeastward down Cottonwood Creek from Sunrise highway. Vallecito Valley is in middleground. Rocks in range on far side of Vallecito Valley are chiefly schist and hybrid rocks. Rocks in left foreground are schist. Elevation of locality from which photograph was taken is about 5,500 feet; point in valley below, where northeast-trending canyon (Cottonwood Creek) in right foreground widens, is about 2,500 feet.
River, in Mexico) and tributaries. The major drainage systems to the east are those of Carrizo and San Felipe Creeks.
Salton (Imperial) Basin. The Salton (Imperial) Basin province bounds the interior upland province on the east. Elevations in the Salton Basin range from about 2,000 feet on its western edge to below sea level in its lowest parts, which are in the vicinity of the Salton Sea, in Imperial County. The lowest part of this province in San Diego County is about 35 feet, on the county line at a point southeast of Ocotillo Wells. The province is characterized by wide, boulder-strewn valleys that are separated by groups of low, irregular hills. These hills commonly are multihued badlands composed of beds of sandstone, shale and conglomerate. Within San Diego
\
Photo 4. View north across Hellhole Canyon toward steep slopes on west side of Borrego Valley. Rocks in foreground and in low parts of ridges in background are mainly schist and gneiss. Highest mountain to left is composed of granitic rocks, probably Bonsall tonalite.
County the province is enclosed by Anza-Borrego Des- ert State Park. Part of the eastern edge of the county is enclosed by the Colorado Desert which is mostly in Im- perial County.
CLIMATE AND VEGETATION
The climate of San Diego County ranges from very mild along the coast, to relatively extreme in the mountains and desert. Along the coast, the average Fahrenheit temperatures during the summer range from the 60's and lower 70's at night to the high 70's during the day. In the winter they range from about 50 degrees at night to the upper 60's during the day. Fifteen to 30 miles inland, at localities such as Escondido and El Cajon, the average temperatures during the summer range from
Photo 5. San Jose Valley area, view southeast. Lake Henshaw is in middleground. Scarp along Elsinore fault forms west side of valley.
1963]
San Diego— Introduction
17
the 50's at night to the 80's and 90's during the day; and during the winter range from the 40's at night to the 60's and 70's in the daytime. In the mountainous areas of the county, the daily summer temperatures range from 60 degrees at night to the 70's and HO's during the day; and during the -winter range from the 30's and 40's at night, to the 40's and 50's during the day. Daytime tempera- tures on the desert during the summer are commonly well over 100 degrees and in the winter are about 70 degrees F.
Precipitation occurs mainly during the winter months as rain, with snow common only in the high mountains. Annual precipitation along the coast is about 10 inches, and ranges upward inland to about 50 inches in some of the highest mountain areas, then drops to 5 inches or less on the desert.
Vegetation along the coast consists of chaparral, sage- brush and some grass. Oak, pine and other varieties of trees are common in the higher areas.
FIELD WORK
The present investigation was started in January 1953 by Richard M. Stewart who was then assigned to the Los Angeles office of the Division of Mines. The project was interrupted with Mr. Stewart's transfer to the San Francisco office in November 1955. It was resumed in September 1956 by F. Harold Weber, Jr., who worked nearly full time on the project until its completion in July 1959. George B. Cleveland, of the Division of Mines and Geology, and Roy M. Kepner, Jr., of the San Diego County Division of Natural Resources, also contributed, as indicated in the acknowledgments.
The data presented in the descriptions of mineral de- posits in the text and tabulated lists were prepared mainly from notes taken during short visits to properties. Visits ranged in duration from a few minutes to one day, and probably averaged between one and three hours. Some deposits were mapped in detail by Brunton compass and tape survey. Geologic reconnaissance mapping to com- plete unmapped areas for the base map (PI. 1) was compiled on U.S. Geological Survey topographic maps of 1:62,500 and 1:24,000 scales. A ' total of about 210 days was spent in the field by all investigators.
Other information included in descriptions, such as that on property ownership and holdings, historical data, and the nature of inaccessible workings, was obtained from previously published reports, property owners, longtime residents of the county with a knowledge of the mining activities, and Mr. Kepner. Property ownership data also were obtained from the offices of the San Diego County Recorder and Assessor.
ACKNOWLEDGMENTS
For the part of the report on "Mineral Resources and Mining," George B. Cleveland prepared the section on "Clay," and Roy M. Kepner, Jr., gathered and tabulated most of the data for the section on "Sand and Gravel, and Crushed and Broken Stone." Richard M. Stewart
prepared the section on "Arsenic," and many of the descriptions of deposits in the tabulated lists, especially for metallic commodities. The project was supervised by Dr. Lauren A. Wright, who also reviewed and edited the report. In addition, William E. Ver Planck furnished valuable criticism.
The members of the staff of the Division of Mines and Geology who worked on this report are indebted to Mr. Roy M. Kepner, Jr. and Miss Barbara Biewener, of the San Diego County Division of Natural Resources, for their continuing interest in the entire project, and for their assistance with many problems involving field- work and compilation of the report. In addition, Mr. Kepner arranged flying trips to take photographs for the report.
Dr. Richard H. Jahns, California Institute of Technol- ogy, kindly furnished the division with unpublished data on the areal geology, pegmatites and mines of the Mesa Grande district. Dr. Richard Merriam, University of Southern California, lent unpublished geologic maps of the Escondido region which were used in compiling the base map. Mr. T. W. Dibblee of the U.S. Geological Survey modified for this report a previously published geologic map. Dr. Cordell Durrell, University of Cali- fornia at Los Angeles, lent reports and maps of the Hilton calcite deposit.
The writers would also like to thank mine owners and others who assisted them during the fieldwork and com- pilation of the report, especially to L. B. Spaulding of Ramona, Frank Herron of Julian, Fred Elliot of Manza- nita, H. J. Phillips of El Cajon, C. C. Pease of San Diego, Robert Harris of Rancho Santa Fe, R. R. Dye of Warner Springs, and H. J. Jory of South Pasadena. The late Frank Lane of Julian furnished information regarding the Julian district.
The maps in this report were drafted by Richard A. Crippen, Jr., Supervising Geological Draftsman, and Dor- ismae Weber. The manuscript, in various stages, was typed by Mrs. Geraldine Saddler, Mrs. Mary March- banks, and Mrs. Elizabeth Clark.
The cover was designed by Elinor H. Rhodes and Sarah Ann Davis.
GEOLOGIC FEATURES
PREVIOUS INVESTIGATIONS
The first published reference to the geology of San Diego County apparently was that written in 1792 by Jose Longinos Martinez, who had noted occurrences of garnet and tourmaline on the mainland during a Spanish expedition to California. Reports dealing specifically with geologic features of the county were first published in the 1850's. These were travelog-like accounts written mainly in conjunction with: (1) surveys for possible railroad routes (Thomas Antisell, 1856; W. P. Blake, 1858); (2) a coast survey report (W. P. Blake, 1856); and (3) the survey from 1849 to 1851 of the boundary between the United States and Mexico (C. C. Parry and A. Schott, 1857; C. C. Parry, 1857; T. A. Conrad, 1857;
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California Division of Mines and Geology
[County Report 3
J. Hall, 1857). The region that now is San Diego County was first included on a geologic map by Blake (1858). During the 1860's W. M. Gabb (1864, 1869) prepared descriptions of Cretaceous and Eocene fossils, including many from the San Diego region, for the second Geo- logical Survey of California.
The Eighth Annual Report of the California State Mining Bureau, published in 1888, contains a short, in- formal account of the geology of the county in "Mineral resources of San Diego County" by W. A. Goodyear. Part of this report was written from notes taken by Goodyear in 1872 for the second Geological Survey of California, which had been disbanded in 1874. In 1893 the bureau published a longer, more descriptive account entitled "Geology of San Diego County: also of portions of Orange and San Bernardino Counties" by H. W. Fair- banks (at that time San Diego County also included Riverside and Imperial Counties). This account still is a useful geologic reference. In 1914 the bureau published a report by F. J. H. Merrill which included a short sec- tion on geology, but was mainly about the mineral resources.
The first detailed geologic report, with an accompany- ing geologic map, to cover a large part of the county, was' written in connection with a ground water study of the western part of the county by A. J. Ellis and
C. H. Lee, and published by the U.S. Geological Survey in 1919.
During the 1920's, the general geology of the county became much better known through the work of A. O. Woodford (1925) in the north coastal region; M. A. Hanna (1926a, b) in the La Jolla region; J. S. Brown (1922, 1923) in the Salton Basin region; F. S. Hudson (1922) in the Cuvamaca. region; and others. During this time and before, W. T. Schaller and others studied the pegmatite deposits in the central part of the county.
During the 1930's, the granitic and metamorphic rocks were studied, principally by E. S. Larsen, Jr. (1941, 1945, 1948) in the northwest part of the countv. Other workers were C. S. Hurlbut, Jr. (1935), F. S. Miller (1937) and W. J. Miller (1935a, 1946). During the period from the 1930's to the 1950's, studies of the stratigraphy and pa- leontology of sedimentary rocks of the south coastal area were continued, mainly by L. G. Hertlein and U. S. Grant, IV (1939, 1943, 1944, 1954). During the 1940's and 1950's, additional studies were made of the batholithic rocks in the central and southeast parts of the county by Richard Merriam (1941, 1946, 1953, 1954, 1955, 1959);
D. L. Everhardt (1951); and Baylor Brooks and Ellis Roberts (1954). Studies of pegmatite deposits were con- tinued, mainly bv R. H. Jahns (Jahns and L. A. Wright, 1951; Jahns, 1954c; Jahns and J. B. Hanley) and Hanley (1951). Studies of (1) ground water were carried out by the California Department (formerly Division) of Water Resources (California Division of Water Re- sources, 1935, 1936, 1949, 1951, 1954, 1956); (2) marine geology by Scripps Institute of Oceanography (F. P. Shepard, with others, 1940 to 1951; K. O. Emery, with
others, 1941 to 1960; and others); and (3) soil studies by the United States Forest Service (United States For- est Service, 1957). In 1954 two important papers dealing partly with the county were published in California Di- vision of Mines Bulletin 170, "Geology of Southern Cali- fornia": (1) "Geology of the Imperial Valley Region", by T. W. Dibblee, and (2) "Geology of the Peninsular Range Province" by R. H. Jahns. In the late 1950's studies of the geology of the San Diego region were being made by Gordon Gastil, E. D. Milow, and students of San Diego State College, San Diego.
DESCRIPTIONS OF THE ROCKS METAMORPHIC ROCKS (CRETACEOUS AND/OR OLDER)
Rocks in San Diego County that are older than the batholith of Southern California consist mostly of meta- sedimentary rocks which in a few places are interbedded with metavolcanic rocks. Some of these rocks may be as old as Paleozoic, or perhaps even Precambrian, and others may be as young as Early Cretaceous. The metasedimen- tary rocks are overlain unconformably by mildly meta- morphosed volcanic rocks which may range in age from Jurassic to Cretaceous.
Metasedimentary Rocks (Cretaceous and/or Older)
Metasedimentarv rocks are exposed throughout the Peninsular Range province in Riverside and San Diego Counties of California and in Baja California. Such rocks in San Diego County were first described in detail in reports that dealt with the Julian gold mining district. Metasedimentary rocks in that district were first named the Julian group by Merrill (1914), and then mapped and renamed the Julian schist series by Hudson (1922). The latter term was shortened to Julian schist by Don- nelly (1934), and this name has been widely used by more recent workers in the central and southeastern parts of the county (Merriam, 1946, 1959; unpublished 1955; Everhardt, 1951; Brooks and Roberts, 1954). In the north- western part of the county the metasedimentary rocks were mapped and described by Larsen (1948) as the Bed- ford Canyon formation, whose type section is in the Santa Ana Mountains, Riverside County. In 1954, in a paper on the geology of the Peninsular Range province, Jahns (1954b, PI. 3) differentiated the rocks in the west and central parts of the county from those in the north- central and eastern parts by referring to the former as "younger metamorphic series" and to the latter as "older metamorphic series." Previously unmapped bodies of metamorphic rocks in the eastern part of the county have been outlined bv reconnaissance mapping for this report (see PI. 1).
Distribution. The metasedimentary rocks occur as inclusions, pendants, and screens which are bounded mainly by younger granitic rocks of the batholith of Southern California. These bodies range in size from small inclusions less than several feet in length, which are distributed through certain granitic rocks (e.g. Bonsall tonalite) (Photo 11), to bodies as much as several miles
1963
San Diego— Geologic Features
19
wide and many miles long (see PI. 1). About 280 square miles in San Diego County are underlain by these rocks, excluding bodies too small to be mapped— those which are part of granitic rocks, and those included with "Hy- brid Gneisses and Associated Quartz Diorite and Gran- odiorite" (which see).
Alost bodies of metamorphic rocks, except necessarily the screens, trend north to northwest, parallel to the structural trend of the region. Exceptions also include the rocks on the north and south sides of the Elsinore Fault, in the southeast corner of the county, which trend north to northeast. Lateral contacts of bodies in the east- central part of the county appear to dip inward, suggest- ing that those bodies are wedge-like downward in verti- cal cross section. Some of the other bodies, however, appear to dip steeply eastward. Layering within bodies, except in their central parts, commonly is parallel to the attitude of contacts of the bodies with surrounding rocks. In central parts of many bodies the layering commonly dips eastward or northeastward.
Lithology. The metasedimentary rocks of San Diego County are predominantly quartz-mica schist. Less abundant types are quartz-mica-feldspar schist, mica schist, and gneiss. Uncommon to rare varieties of schist contain various proportions of secondary amphibole, silli- manite, andalusite, and graphite. iMinor accessory min- erals include magnetite-ilmenite, red garnet and zircon. Quartzite commonly is interlayered with schist. The quartzite layers generally are one foot or less in thickness, but some are as much as 100 to 300 feet thick and nearly two miles long (Hudson, 1922, p. 183; Merriam, 1946, p. 227). Relict structures suggestive of cross-bedding were noted in quartzite near Ramona by Merriam (1946, p. 227), and by the present writer at Dos Cabezas.
The schist is coarser grained in the eastern part of the county than in the western part, and gneissic rocks are more common in the eastern part, especially in the area west of Dos Cabezas, in the western part of the Coyote Mountains (Dibblee, 1954, p. 21), and in Coyote Moun- tain (near Borrego Springs). Abundant pegmatite and other minor intrusive bodies cut the metamorphic rocks in the area between the Coyote Mountains and Jacumba (Photo 6) and in the area north of Warner Springs, along the north boundary of the county.
Injection gneiss probably is common in the metamor- phic rocks (Hudson, 1922, p. 184-187; Larson, 1948, p. 20; Merriam, 1946, p. 232), but appears to be limited to areas along contacts between the metamorphic rocks and younger granitic rocks. Amphibolite has been described in the Julian-Ramona region by Everhardt (1951, p. 58- 60), Hudson (1922, p. 183), and Merriam (1946, p. 229). Hybrid rocks composed of granitic bodies and a rela- tively large proportion of included metamorphic rocks are common in the middle of the county (see section on "Hybrid Gneisses and Associated Quartz Diorite and Granodiorite").
Crystalline limestone-dolomite and tactite occur mainly as small inclusions, pendants and layers in the metasedi-
Photo 6. View north along Carrizo Canyon in Jacumba Mountains in southeast part of county. Metamorphic rocks in foreground and middle- ground are cut by abundant pegmatite dikes; those in left background are cut by irregular intrusive bodies of granitic rocks. Fish Creek Mountains are in left distant background.
mentary, hybrid and granitic rocks, and are limited al- most entirely to the eastern part of the county— east of meridian 116° 45' (Photo 93, Fig. 58). In the extreme eastern part of the county— in the Coyote Mountains (Fig. 40), Dos Cabezas area (see Fig. 42 and Photo 50) and the Santa Rosa Mountains— layers of crystalline lime- stone and dolomite, interlayered with schist and/or gneiss and/or quartzite are as long as one to three miles and are as thick as several hundreds of feet. The broad distribution of metasedimentary rocks in San Diego County is similar to that in western Riverside County, as described by Larsen (1948). In both counties, layers of crystalline limestone and dolomite are more common in the eastern part of the batholith than in the western part. Before metamorphism the metasedimentary rocks of San Diego County consisted chiefly of shale, siltstone, and claystone, with a minor proportion of quartz sand- stone, arkose and probably graywacke. The latter three rocks were probably most common in the central and eastern parts of the county. Conglomeratic units proba- bly were rare, as they have been noted only in the Pala area (Jahns and Wright, 1951, p. 9). The previous exist- ence of volcanic rocks in the central part of the region is indicated by the presence of amphibolite bodies, as described by Everhardt (1951), Hudson (1922), and Merriam (1946).
Age, Correlation, Structure, and Thickness. The only diagnostic fossil noted in the metamorphic rocks of San Diego County was described by Hudson (1922, p. 190) as follows:
A fossil was found by Mr. D. D. Bailey of Julian in the small area of metamorphic rock that lies in the granite about a mile southeast of Banner. This was submitted by Mr. H. L. Huston of San Francisco to Dr. J. P. Smith, who pronounced it "a slender ammonite that is without much doubt Triassic." The fossil is an imprint of an ammonite on the surface of an angular pebble of dark gray, quartzite rock. It was found as float.
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On the basis of this scanty evidence a Triassic age for the metamorphic rocks of the central and southeast-cen- tral parts of the county has been accepted tentatively by most recent workers in the region. On this evidence also, and on the basis of lithologic similarity, these rocks have been correlated with the Bedford Canyon formation of Larsen (1948). The type locality for that formation is in the Santa Ana Mountains, Riverside Countv, but it has been traced as far southeastward by Larsen (1948, PI. 1) as trie Escondido and Pala areas of San Diego County. The Bedford Canyon formation has been considered as Triassic in age, but recent work by Silbering, Schoell- hamer and Gray (1961) has shown that at least part of the formation may be Middle or Late Jurassic in age.
Additional fossil occurrences outside of the county suggest that some of the prebatholith rocks of San Diego County are older than Triassic and Jurassic in age. At a locality in Riverside County, about 30 miles east of the Santa Ana Mountains, a fragment of limestone contain- ing a coral was found in talus at .the base of a limestone cliff. The fossil was identified as Mississippian in age (Webb, 1939, p. 198-201). On the east edge of the San Jacinto Mountains, also in Riverside County, fragments of possible crinoids of Paleozoic age have been found (Miller, 1944, p. 25). In Baja California fossils as young as early Upper Cretaceous have been found in prebatho- lith rocks (Bbse and Wittich, 1913; Woodford and Harriss, 1938, p. 1330-1331).
On the basis of the fossil evidence in western Riverside County, and the general increase in metamorphism from west to east in both San Diego and western Riverside Counties, the rocks may range in age from younger to older from west to east. This has been suggested in part by Larsen (1948, PI. 1), who separated rocks of Triassic age on the west from rocks of Paleozoic age on the east, and by Jahns (1954b, PI. 3), who separated the meta- sedimentary rocks along the eastern edge of the county as "older metasedimentary series" in contrast to "younger metasedimentary series" in the west. The general dip of the rocks in most parts of the country is to the east, how- ever, and a single indistinct graded bed observed by the writer in the Chieftain Mine in the Julian district sug- gested that its top is to the east, and therefore up. Thus, if the older rocks are to the east, the sections at Julian and in other areas probably would have to be at least partly overturned. Although the structure of the rocks appears simple through most parts of the county, tight folds noted at several localities suggest that isoclinal fold- ing may be much more common than has been indicated by mapping. These folds are ( 1 ) a tight isoclinal fold exposed on the north side of Box Canyon in the Ori- flamme Mountains (Photo 7), (2) a suggested isoclinal fold that contains layers of the Verruga limestone deposit near Ranchita, (3) a possible tight fold that contains the Sentenac limestone deposit near Ranchita, and (4) tight folds, including isoclinal folds, which contain layers of limestone, at Dos Cabezas (see Fig. 42).
An estimate of the thickness of the rocks cannot even be suggested from the meager evidence at hand. As ex-
Photo 7. View north toward lower slopes of Oriflamme Mountains across Box Canyon, from Seyer tungsten deposit. Tightly folded meta- morphic rocks (darker rocks) are intruded concordantly to discordantly by granitic rocks (lighter colored rocks). Eastern edge of body of granitic rocks that constitutes higher part of the mountains is at upper left corner of photo.
posures are as wide as several miles, however, and there is a fairly distinct change in lithology from west to east, the total thickness must be many thousands of feet.
Economic Significance. The gold-bearing deposits of the Julian and other lesser districts in the east-central part of the county are mostly in schist (see "Gold" under "Mineral Resources and Mining"). Tungsten de- posits, chiefly in tactite bodies in metamorphic rocks, are scattered through the central and eastern parts of the countv. Crystalline limestone and dolomite deposits in- terlayered chiefly with schist are found mainly in the northeast and southeast parts. Manganese and graphite deposits occur in metamorphic rocks in the county, but none has been mined. Quartzite has been quarried at one locality for use as dimension stone.
Metavolcanic Rocks (Jurassic and/or Cretaceous)
Mildly metamorphosed volcanic rocks, probably of Jurassic or Cretaceous age, are exposed discontinuously as a north-northwest trending belt that lies within a few miles of the coast (see pi. 1 ). The rocks were first named the "Black Mountain volcanics" (photo 1) by Hanna (1926a, p. 199), but later were renamed "Santiago Peak volcanics" by Larsen (1948, p. 22-23), because "the name Black Mountain had been used for a basalt of Pliocene or Pleistocene age in Northern California."
Distribution. Of about 1 70 square miles in the county underlain by metavolcanic rocks, nearly 85 square miles are underlain by a large mass which is exposed continu- ously from the Mexican border to La Mesa, mainly as a group of rugged mountains and hills. The metavolcanics are bounded by other metamorphic rocks, which in gen- eral are older than the volcanics, and by younger igneous and sedimentary rocks of Cretaceous and Tertiary age. The widest continuous exposure of these rocks in the countv is 1 1 miles, near the Mexican border, across the
1963
San Diego— Geologic Features
21
San Ysidro Mountains (photo 26). Surface exposures and well data (Hanna, 1926a, p. 200; Jennings and Hart, 1955, p. 7 1 ) show that the belt of rocks bends seaward beneath younger sedimentary rocks in the area east of La Jolla and that at depth it probably extends westward beneath the sea throughout the San Diego region. The metavol- canics are very resistant to erosion, and perhaps, during Cretaceous and Tertiary times, hills and mountains com- posed of these rocks acted partly as a barrier which lim- ited the access of the sea and consequently restricted deposition of Cretaceous and Tertiary marine sedimen- tary rocks to a relatively narrow belt along the present- day coast.
The regional strike of the layering in the metavolcanic rocks is north to northwest, most commonly north- northwest to northwest, and parallel to the trend of the entire belt. The metavolcanics dip moderately to steeply southwest along the west slope of the Santa Ana Moun- tains, in Riverside Coutv, and in the area near the border between San Diego and Riverside Counties (Engel, 1959, pi. 1; Larsen, 1948, p. 23-24); the rocks dip moderately to steeply northeast in the pyrophyllite-bearing area northeast of Rancho Santa Fe (Jahns and Lance, 1950) and in the Dulzura district, which is in the eastern part of the San Ysidro Mountains; the rocks dip steeply east on the northwest edge of Black Mountain (Hanna, 1926a, p. 202); in other areas the structure is obscure.
Lithology. The metavolcanic rocks consist of flows, tuffs, breccias, and agglomerates, with a very small pro- portion of interbedded clastic sedimentary rocks. The metavolcanic rocks range in composition from rhyolite to basalt, but andesite, dacite and quartz latite are the most prevalent types. In the San Ysidro Mountains rocks that range from rhyolite to quartz latite are common. The rocks generally are porphvritic, commonly with dark minerals completely altered and the feldspars slightly to moderately altered. Hanna (1926a, p. 200) and Larsen (1948, p. 33) both recognized that the rocks show a slight increase in regional metamorphism from west to east. The most common alteration mineral prob- ably is chlorite; other common to uncommon ones are quartz, serpentine, hornblende, epidote, carbonate min- erals, albite, pyrite, and pyrrhotite. The rocks are vari- ously colored. The andesitic and latitic phases, however, are dark grayish-green to almost black and commonly are known as "greenstone." Because of the presence of iron-bearing minerals, most phases of the rocks weather pale brown to reddish brown.
Age, Correlation, and Thickness. In Riverside County the metavolcanic rocks rest unconformably on the Bed- ford Canyon formation which perhaps ranges in age from Triassic to Jurassic. Throughout San Diego County the metavolcanics have been intruded by plutonic rocks of the batholith of Southern California w hich are prob- ably early Late Cretaceous in age. These relationships suggest that the metavolcanic rocks in San Diego County may be as old as Late Triassic or Early Jurassic and as young as Early Cretaceous. The interbedded metavol-
canic and metasedimentary rocks of the San Diego region have been correlated tentatively by Milow (1961) with the Early Cretaceous Alisitos formation of Baja Califor- nia (also see Allison, 1955).
The total thickness of these rocks has not been deter- mined: a continuous section 2,000 feet thick was exam- ined by Hanna (1926a, p. 203) north of La Zanja Can- yon; and Larsen (1948, p. 23) stated simply "that the thickness of the volcanic rocks cannot be measured, but it must have been thousands of feet and probably many thousands of feet."
Economic Significance. Three pyrophyllite deposits in metavolcanic rocks northeast of Rancho Santa Fe were being worked in 1958 (see "Pyrophyllite" under "Min- eral Resources and Mining"). In the same general area are two deposits of "greenstone" which have been worked for roofing granules. In the San Diego region two companies quarry metavolcanic rocks for use as broken and crushed stone (see under "Sand and Gravel, and Crushed and Broken Stone"). In addition, deposits of clay, gold, copper, arsenic, and iron in these rocks have been worked in the county.
Hypabyssal Intrusive Rocks Associated With the Metavolcanic Rocks
Fine-grained, hypabyssal intrusive rocks associated with the metavolcanic rocks discussed above were con- sidered by Larsen (1948, p. 27-32) to be about the same age as the metavolcanics and hence older than other intrusive rocks of San Diego County. These rocks range from granite to granodiorite porphyry and, their volcanic equivalents, rhyolite to dacite. At least 25 square miles are underlain by these rocks. They have not been mapped, however, south of latitude 33°00'.
Economic Significance. A single locality in these rocks, near Oceanside, has been worked unsuccessfully for riprap (see Marron Quarry in tabulated list under "Sand and Gravel, and Crushed and Broken Stone").
HYBRID GNEISSES AND ASSOCIATED QUARTZ DIORITE AND GRANODIORITE (CRETACEOUS AND/OR OLDER)
Rocks shown on the geologic map that accompanies this report as "Hybrid Gneisses ("Mixed Rocks") and Associated Quartz Diorite and Granodiorite" underlie about 270 square miles of San Diego County. The rocks were first described by Fairbanks ( 1893a, p. 78, 82) from exposures near Jacumba and in the Deer Park area, north of Pine Valley. The name "mixed rocks" was first ap- plied by W. j. Miller (1935a, p. 134-137) who mapped and described the rocks along U.S. Highway 80. This name was retained by Everhardt (1951) and Merriam (1958, 1959, 1955). The term "hybrid gneisses and asso- ciated quartz diorite and granodiorite" was initiated by Jahns (1954b).
Hybrid gneisses and associated intrusive rocks are ex- posed discontinuously in a crude, northwest-trending belt which extends northwestward from the Jacumba area to the Palomar Mountain region. The largest region
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California Division of Amines and Geology
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, ' fiL'
A- v."''
fc C
^fe&,;:
Photo 8. View east toward contact between "hybrid rocks" and asso- ciated quartz diorite, at right, and Julian schist, at left; east side of State Highway 79 about 2 miles south-southeast of Julian.
Photo 9 (below). Julian region, view southeast. Oriflamme Mountains in right middleground. Trace of Elisnore fault shows from lower left to upper right. Earthquake Valley in left background. Rocks exposed in background are mostly hybrid gneiss and schist with a minor proportion of granitic rocks. Upper part of Oriflamme Mountains is composed of granitic rocks. Foreground underlain by Julian schist. Ranchito gold mine is just above trees in small valley along Elsinore fault, directly below top of Oriflamme Mountains.
underlain by these rocks is near the center of the belt, and includes the Santa Ysabel-Julian area.
These hybrid rocks include two general types: (1) rocks that range from migmatite (or injection gneiss) to banded gneiss; and (2) rocks that are mainly granitic or metamorphic and contain, respectively, very abundant bodies of metamorphic or granitic rocks.
(1) In the Santa Ysabel-Julian and Laguna Mountains regions the hybrid rocks range from migmatite (or in- jection gneiss) to banded gneiss. The migmatite is be- lieved to have been formed by lit-par-lit injection of granitic magma into schist, whereas the banded gneiss may have either a granitic or metamorphic origin (Ever- hardt, 1951; Merriam, 1959). Relict textures in the banded gneiss suggest that the rocks are derived, at least in part, from the Julian schist (Donnelly, 1934, p. 340- 345). Some of the contacts between the schist and hy- brid rocks are sharp, however, as shown in a roadcut near Julian (Photo 8). In addition to the layers of granodiorite and quartz diorite that occur as part of the migmatite, small irregular bodies of Stonewall quartz diorite (Hudson, 1922; Merriam, 1959) and Stonewall granodiorite (Donnelly, 1934; Everhardt, 1951) are asso- ciated with the hybrid rocks. Some of these bodies have been mapped by Merriam (1946, 1959, 1955), Everhardt (1951), and Jahns and Hanley (in preparation).
(2) Also included as hybrid rocks on the accompany- ing geologic map are: (a) rocks that are mainly granitic but with a major proportion of schist inclusions, and (b)
1963]
San Diego— Geologic Features
23
rocks that are mainly metamorphic, but which contain abundant granitic bodies. Many of these terranes could be divided into granitic and metamorphic rocks by de- tailed mapping on a large scale. Included as hybrid rocks of this type are parts of the Palomar Mountain, Ori- flamme Mountains, and Jacumba regions.
Geologic relationships have suggested to the latest workers in the region (Everhardt, 1951; Merriam, 1955, 1959) that the Stonewall quartz diorite and granodiorite are older than the intrusive rocks of the batholith of Southern California, and they have dated them tenta- tively as Jurassic. However, one sample of Stonewall granodiorite has been dated by the lead-alpha method as 96 million years old, which suggests that the unit is Cretaceous in age (Larsen and Schmidt, 1958, p. 19), and hence part of the batholith.
Economic Significance. Some of the gold mines in the Julian and Boulder Creek districts and in the Laguna Mountains region are in hybrid (or "mixed") rocks (see "Gold" under "Mineral Resources and Mining"). Tung- sten minerals occur in small bodies of tactite in hybrid rocks in the hills northeast of San Felipe Valley and in the Laguna Mountains region (see "Tungsten").
INTRUSIVE ROCKS OF THE BATHOLITH OF SOUTHERN CALIFORNIA (CRETACEOUS)
The granitic and gabbroic rocks* of San Diego County are part of the batholith of Southern California, which is exposed southward from Riverside, in Riverside County, to the tip of Baja California, a distance of about 1,000 miles (Larsen, 1948, p. 134, fig. 3). Within San Diego County the batholith is as much as 70 miles wide, and underlies areas which comprise nearly 1,900 square miles, or about two-fifths of the county. Hybrid rocks, which contain a significant proportion of granitic rocks, underlie an additional 270 square miles. In other areas, rocks of the batholith are covered by younger sedi- mentary deposits.
A large part of the batholith in San Diego County was first mapped and studied in detail by E. S. Larsen, Jr. (1948). The results of his study include a map of the northwest part of the county, south to parallel 33°00', and east to meridian 117°00'. South of Larsen's area, Hanna (1926a) divided the batholithic rocks into "quartz diorite" and "gabbro." East of Larsen's area, Merriam (1946; 1954; 1955, unpublished) has used Larsen's nomen- clature for the geologic units in his studies in the west- central, central and southeast parts of the county. Sev- eral workers in the Julian region, in addition to Merriam, have mapped and/or named intrusive units (Hudson, 1922; Donnelly, 1934; Everhardt, 1951). In the southern part of the county, Miller (1935a) mapped and named several units. In the Jacumba region, Brooks and Roberts (1954) mapped intrusive rocks, using Miller's names. In the central and northern part of the county, Jahns has
* In this report the term granitic rocks refers to the group of plutonic igneous rocks which ranges from granite to diorite in composition. The term gabbroic refers to rocks which range from diorite, through gabbro, to peridotite.
mapped several small to wide areas in detail or reconnais- sance (Jahns, 1954a,b,c; Jahns and Wright, 1951).
The batholithic rocks were emplaced as many distinct units, each of which is believed to have been intruded after the preceding unit had crystallized or nearly crys- tallized (Larsen, 1948, p. 137). Several of the units (e.g. Bonsall tonalite and Green Valley tonalite), which were intruded as small to large bodies, underlie substantial areas through large regions of the batholith. The se- quence of intrusion of the rocks is believed to have ranged chronologically from gabbro, through tonalite, and granodiorite, to granite (Larsen, 1948). Tonalite and granodiorite are the most common types. The time re- quired for crystallization of the batholith was estimated by Larsen (1945) to be on the order of a few million years. The age of the batholith on the basis of fossil evidence in Baja California, is believed to be early Late Cretaceous (Bose and Wittich, 1913; Woodford and Harriss, 1938; Larsen, 1948). By the lead-alpha method of age dating, the rocks have been dated as 110 ± 13 million years (Larsen, Gottfried and others, 1958, p. 49).
Gabbroic Rocks
The oldest intrusive rocks of the batholith are bodies of closely related gabbroic rocks which are widespread in the western part of the county. They cover a total area of about 160 square miles. The rocks are limited to the area southwest of the Elsinore Fault Zone, except in the Pala area, where a body of gabbro is cut by faults of the Elsinore zone. In the southeast corner of the county, only one body of gabbro is known. This is a small, al- tered body northeast of Jacumba which contains the Circle Group Vermiculite Deposit.
The gabbroic bodies are mostly irregular in plan, ex- cept in the northwest corner of the county, where many are elongate northwestward. Most of them are rather small— one to five square miles. The largest one— about 25 square miles in area— underlies a large part of the Cuyamaca region, in the central part of the county. From this body, two elongated groups of smaller bodies extend to the southwest and south (see PI. 1).
The gabbroic rocks of San Diego County were first studied in detail by Hudson (1922, p. 193-207) who rec- ognized 15 varieties of basic plutonic rocks in the north part of the Cuyamaca body. Because these rocks ranged from diorite to peridotite, he called the body the "Cuyamaca basic intrusive." Similar rocks in the western part of the county were first described by Hurlbut (1935) who named them the "San Marcos Mountain gabbro." F. S. Miller (1937, p. 1397-1426) described the gabbroic rocks in the northwest part of the county in great detail, shortening Hurlbut's term to "San Marcos gabbro." This name has been used to the north and west of Hurlbut's area by Larsen (1948), and in the central and southeast parts of the county by Merriam (1946; 1959; 1955). In the Cuyamaca region, Creasey (1946) and Everhardt (1951) modified Hudson's original term to "Cuyamaca gabbro." In the south part of the county, W. J. Miller (1935a, 1946) used the term "Viejas Moun-
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tain gabbro-diorite," as well as San Marcos gabbro and Cuyamaca gabbro.
Gabbroic rocks in the interidr part of the county form bold hills and mountains, with somewhat smooth, brush-covered slopes. Where soil forms it is dark reddish brown. Some of the hills and mountains underlain by gabbroic rocks resemble volcanic cones.
The rocks are of many types, which range from dio- rite to peridotite; most common are varieties of gabbro and norite. The rocks range in texture from fine- to coarse-grained. In the Vista region, F. S. Miller (1937, p. 1399-1400) found that the average rock was a medium- grained, dark-gray norite. In the Cuyamaca Peak quad- rangle, hornblende gabbro and norite are the most com- mon types (Everhardt, 1951, p. 66-72). In the Pala area, olivine-hornblende-hypersthene gabbro is most common (Jahns and Wright, 1951, p. 9).
Economic Significance. The gabbroic rocks along the western edge of the exposed part of the batholith are an important source of "black granite" for use as dimension stone (see "Dimension Stone" under "Mineral Resources and Mining"). In the Pala and Mesa Grande districts, these rocks contain important gem-bearing pegmatite
Photo 10. Roodcut showing fracture-controlled weathering of granitic rocks. "View north across U.S. Highway 80, about 4 miles west of Descanso Junction. Slopes in left background comprise boulders of disintegration which have weathered in place.
'J
dikes (see under "Gem Minerals"). Several nickel-cobalt- copper bearing deposits in gabbroic rocks in the central part of the county have been prospected, but not mined (see under "Nickel").
Granitic Rocks
The granitic rocks of the county consist mainly of bodies of tonalite (quartz diorite) and granodiorite, and a few bodies of granite. These bodies range in size from dikes and small irregular bodies of less than several hundred square feet in area, to bodies as much as many tens of square miles in area. The bodies are mostly ir- regular in outline, but commonly are elongate. Contacts between the units generally are sharp. The known map- pable units are described briefly below, from the prob- able oldest to the youngest.
Green Valley Tonalite. The name Green Valley tonalite was used first by F. S. Miller (1937) for rocks in Green Valley, betwen U.S. Highway 395 and Ramona. The Green Valley tonalite is exposed widely in the western part of the county, where its medium- to dark- gray exposures characteristically form deeply weathered lowland to hilly topography. Boulders of disintegration weather commonly from its outcrops (Photo 10). The Green Valley resembles the Bonsall tonalite, but lacks abundant streaked inclusions (Larsen, 1948, p. 53) and is somewhat darker.
Bonsall Tonalite. The name Bonsall tonalite was ap- plied first by Hurlbut (1935, p. 611) for exposures, near Bonsall, of a hornblende tonalite which contains abun- dant inclusions. The name was used later by Larsen (1948) in preference to two others which had been suggested for similar rocks in Riverside County. The rock ranges from light to dark gray; hornblende is the chief dark mineral. The unit is lighter than the Green Valley tonalite, and darker than the Lakeview Mountain tona- lite.
The Bonsall tonalite is probably the most widespread batholithic unit in the county. It underlies a large area in the Fallbrook-Bonsall-Lake Wohlford region (Larsen 1948, PI. 1) and extends discontinuouslv eastward through the north parte of the Ramona and Santa Ysabel Quadrangles. The same rocks may extend discontinu- ouslv northward, northeastward, and eastward into the Palomar Mountain region, into the Warner Springs and Clark Lake quadrangles (Photo 4), and into the north half of the Borrego quadrangle. The Bonsall tonalite also is exposed widely in the south part of the county— south of the Ramona area and west of the Campo area.
Lakez'ieiv Mountain Tonalite. The name "Lakeview Mountain tonalite" is a modification by Larsen (1948, p. 57) of the term "Lakeview tonalite" which had been used previously in Riverside County. The Lakeview Mountain tonalite resembles the Bonsall tonalite, but lacks the abundant inclusions of the latter unit. In the eastern part of the county the Lakeview Mountain tona- lite forms mountains with bouldery, resistant slopes.
i 1963]
San Diego— Geologic Features
25
This unit underlies much of the region in the middle east and southeast parts of the county, where commonly it comprises mountains and hills with bouldery, resistant slopes (Merriam, 1955). It comprises the In-Ko-Pah and the Vallecito Mountains and underlies a large part of the region that extends from Campo east to beyond the Imperial County line. The intrusive rocks in the south- east corner of the county also have been mapped as La Posta quartz diorite (W. J. Miller, 1935a; Brooks and Roberts, 1954) (Photos 17, 45, and 88).
Lake Wohlford Leucogranodiorite. The Lake Wohl- ford leucogranodiorite was named by Larsen (1948, p. 82) for exposures near Lake Wohlford, in San Diego County. The unit has been recognized only in the area between Escondido and Lake Wohlford. It is light gray and fine grained.
Woodson Mountain Granodiorite. Woodson Moun- tain granodiorite is a pale-brownish gray rock which commonly forms bold, almost ledge-like ridges (photo 2). The unit was named by F. S. Miller (1937, p. 1399) for its exposures on Woodson Mountain, a few miles southwest of Ramona. The rocks occur as large bodies over a wide area in the western part of the county, in about the same general area as the Green Valley tonalite.
The Woodson Mountain granodiorite is coarse- grained commonly, and also is commonlv stained with hydrous yellow-brown iron oxides. Many bodies of these rocks have a gneissic or banded structure along their edges (Larsen, 1948, p. 77).
Indian Mountain Leucogranodiorite. The Indian Mountain leucogranodiorite is exposed along both sides of the San Luis Rev River, within a few miles south- west of Pala (Larsen, 1948, PI. 1). The rock is very light gray and fine-grained.
Escondido Creek Leucogranodiorite. The Escondido Creek leucogranodiorite is exposed as two bodies, four to six miles southwest and west of Escondido (Larsen, 1948, PI. 1). It is a light-colored, fine-grained rock which contains inclusions of tonalite.
Roblar Leucogranite. The Roblar leucogranite is ex- posed along the north edge of the county, in the Roblar Canvon area, near Deluz (Larsen, 1948, PI. 1). It is flesh-colored, and aplitic in appearance.
Other Intrusive Bodies. A small part of the granitic rocks of San Diego County have been mapped by Lar- sen (1948, PI. 1) as "miscellaneous granodiorites."
In the Cuyamaca region, small bodies of granite and diorite that have been mapped have not been correlated with rocks of western San Diego County (Everhardt, 1951; Merriam, 1955).
Pegmatite and Aplite Dikes. Granite pegmatite dikes cut granitic and metamorphic rocks in many parts of the county (Fig. 2, Photo 11). They are discussed herein under "Gem Minerals'1 in the section on "Mineral Re- sources and Mining." Aplite dikes are common in the
western part of the county, in parts of the Escondido region, where they cut Green Valley and Bonsall tona- lites (Larsen, 1948, p. 101).
Economic Significance. The granitic rocks of San Diego Countv are a source of dimension stone (see "Di- mension Stone" under "Mineral Resources and Mining"), "decomposed granite," and broken stone for use as rip- rap (see under "Sand and Gravel, and Crushed and Broken Stone"). Granitic rocks are hosts for several gold-bearing deposits in the western part of the county, and several tungsten prospects.
In the Pala and Mesa Grande districts, and several lesser districts, granite pegmatite dikes have been a source of tourmaline and other gem minerals (see under "Gem Minerals"). Pegmatite dikes also have been an important source of feldspar and a lesser source of common quartz and quartz crystal. Several granite aplite dikes in the county contain small deposits of molybdenite.
CRETACEOUS AND TERTIARY ROCKS OF THE SAN DIEGO COASTAL PLAIN REGION
Cretaceous System
Marine sedimentary rocks of Late Cretaceous age are exposed discontinuously along the coastal plain from the border between San Diego and Orange-and-Riverside Counties southward to Point Loma, near San Diego.
The largest area underlain by these rocks extends southward from the north border of the county to within one mile of Las Pulgas Canyon, in Camp Pendleton (see PI. 1). In this area the rocks consist chiefly of brown sandstone with a minor proportion of interbedded shale layers and conglomerate lenses (Woodford, 1925, p. 173; Southwick, 1928). They dip gently to the southwest and overlie metamorphic and intrusive rocks of probable early Late Cretaceous and older age. The strata are re- sistant and form rugged hills along the west side of the Santa Margarita Mountains. The widest part of the Creta- ceous belt in San Diego County is between San Mateo Canyon on the west and San Juan Creek on the east, a distance of about four miles. A thickness of several thous- and feet is suggested. Additional exposures of these rocks may occur several miles to the southeast, along Vander- grift Road, between the San Luis Rev and Santa Mar- garita Rivers (Smith and others, ca. 1920-25).
About 4I/2 miles south of Carlsbad, brown shale inter- bedded with thin layers of sandstone is exposed beneath an area of about one square mile (Jones, 1958). The shale rests on granitic rocks and is overlain by sandstone of Eocene age. It is believed by Jones to be about 250 feet thick. Foraminifera described from these rocks by Bandy (1951) are Late Cretaceous (Tracian) in age.
Along the coast, at La Jolla and at Point Loma, resist- ant sandstone interbedded with shale is exposed (Photo 12). The maximum thickness of these rocks is not known, but is believed to be about 500 feet (Hertlein and Grant, 1954, p. 55). About six miles south of San Diego, "red beds," about 269 feet thick and similar to the Trabuco formation, were intersected by a well (Hertlein and Grant, 1954, p. 55-56). At a locality about two miles
26
California Division of Mines and Geology
[County Report 3
Photo 11. Roadcul- in southwest side of Parayne Hill, on Lake Henshaw-Palomar Mountain road, view north-northeast. Granitic boulders of disin- tegration protrude from cut. Nearly horizontal pegmatite dikes, which range in thickness from 1 to 2 inches to nearly 2 feet, are cut by many step faults at lower right. A nearly vertical, elongate schist inclusion in the granitic rocks is shown in left middleground.
ROAD
To no 1 1 te
Schist
EXPLANATION
Mm
^\\
Pegmatite Boulders of d is i n teg rat ion
Figure 2. Geologic sketch of road cut shown in photo 11.
Fault
1963
San Diego— Geologic Features
27
Photo 12. View west toward La Jollo area. Goldfish Point in middle- ground. Sandstone of Cretaceous age forms resistant wave-cut cliffs.
south of the south end of San Diego Bay, a well inter- sected strata of Cretaceous age, at a depth between 3,900 and 5,529 feet. These strata lie on metavolcanic rocks. At this locality the basal 30 feet of the Cretaceous rocks is conglomerate.
The Cretaceous age of the rocks in the San Diego region was determined first by Gabb (1864), then veri- fied later by Cooper (1894, p. 37-38) who described a suite of fossils collected by Fairbanks (1893a, p. 94-96; 1893c, p. 473-478). The latest discussion of the age of these rocks is by Anderson (1958, p. 66-67, 196). Most workers have accepted the rocks as correlative with the Chico formation of Northern California. Recent work by Milow (1961), however, has shown that the Late Cretaceous rocks of the San Diego region probably can be correlated with the Rosario formation of Baja Cali- fornia.
Tertiary System
Pa/eocene Rocks
The only unit of known Paleocene age in San Diego County is the Tierra del Colorado clay zone, which ex- tends southward into the county a few hundred feet from Orange County (Stauffer, 1945; Davies and Bramlette, 1943; South wick, 1928). A similar reddish zone of weath- ering of probable Paleocene age or early Eocene age is exposed at several known localities in San Diego County, as far south as Olivenhain. These localities are ( 1 ) south edge of Basilone road in Camp Pendleton, about two miles north of the Santa Margarita River (SE.!4 Sec. 35, T. 9 S., R. 5 W., S.B.M. (projected)); (2) one-half mile southwest of Breeze Hill, southwest of Vista (south edge Sec. 26, T. 11 S., R. 4 W., S.B.M.) ; (3) Kelly Ranch Mine area, 4'/2 miles southeast of Carlsbad; and (4) about one mile north-northeast of Olivenhain. (See also Clay
Prospect, Kelly Ranch Mine, Gladding, McBean and Company Mine, and Vitrified Products Company Mine herein under "Clay" by G. B. Cleveland.)
Eocene Rocks
Clastic sedimentary rocks of Eocene age are exposed in the county along the coastal plain from Orange County to Point Loma, and also have been encountered in wells as far south as the Tia Juana River Valley. In the north part of the plain these strata dip gently to very gently westward, and in the south part they dip most commonly very gently westward to southwestward. In the northwest corner of the county the rocks overlie Cretaceous sedimentary rocks with a slight unconformity, and in the central and southern parts overlie granitic and metavolcanic rocks mainly. The Eocene rocks com- monly are overlain by sedimentary rocks of Miocene and , Pliocene age.
sA^In La Jolla Quadrangle, north of San Diego, the 'Miocene rocks have been divided into La Jolla formation (Hanna, 1926a) and the Poway conglomerate (Ellis and Lee, 1919). La Jolla formation consists of three members: Delmar sand, Torrey sand, and Rose Canyon shale. North of La Jolla Quadrangle the Eocene rocks consist chiefly of sandstone, and in the northern corner of the county were correlated with the Tejon formation of upper Eocene age by Dickerson (1916), Woodford (1925) and others. However, Hanna (1926a, p. 215) considered the Poway conglomerate to be correlative with the Tejon formation.
During the late 1950's, Eocene and other rocks of the San Diego region were being restudied in great detail, and partially redefined, by Milow (1961). Milow has recognized an additional unit between the Rose Canyon shale and the Poway conglomerate. In addition, he has
28
California Division of Mines and Geology
[County Report 3
Photo 13. Torrey Pines area. View north-northwest from U.S. Highway Rose Canyon shale (at left), both Eocene in age, extends north-northwest of Eocene age, is exposed in outcrops shown in upper right part of photo
101. Contact between gently dipping strata of Torrey sand (at right) and from deposit of Linda Vista Terrace in foreground. The Delmar sand, also
concluded that much of the so-called Poway conglom- erate actually consists of reworked deposits which are younger than Eocene in age.
Sandstone Undivided (Includes Delmar and Torrey Sand Members of La Jolla Formation). The lower part of the Eocene sedimentary rocks of San Diego County
is exposed as a nearly continuous belt as wide as seven miles which extends southward from the Orange county line to Torrey Pines State Park. The Delmar sand, about 200 feet thick, is exposed along the coast near the town of Del Mar (Photo 13). The Torrey sand, 25 to 200 feet thick, is exposed northeastward and northward from Torrey Pines Park (Photos 1, 13, and 14). The Delmar
Photo 14. Roadcut in Torrey Pines State Park, view northwest. Torrey sand (Eocene) is overlain by deposits of the Linda Vista Terrace (Pleistocene) which at this locality are several feet thick.
1963
San Diego— Geologic Features
29
is distinguishable from the Torrey sand chiefly because it contains abundant interbedded clay and silt layers and it is not as white as the Torrey.
The Eocene sandstone that lies north of La Jolla Quadrangle generally resembles the Torrey sand of Hanna ( 1926a), and consists chiefly of white, uncemented sandstone with a very small proportion of thin layers of shale, siltstone and conglomerate. The sandstone is mainly fine- to medium-grained, and composed nearly wholly of feldspar and quartz with a very small pro- portion of silt, clay, and dark minerals. In contrast to the Cretaceous and Pliocene sands of the county, these sands contain only a trace of biotite (Woodford, 1925, p. 174; Southwick, 1928). The sandstone is exposed in rolling hills (Photo 77), and in sides of steep-walled canyons whose slopes are snow white to slightly brown- stained, and commonly exhibit rill-like erosional features (Photo 1). A detailed discussion of the lithology of the sands in the San Luis Rev Quadrangle is provided by Jones (1958).
The thickness of the sandstone increases northward, reaching a maximum of about 3,300 to 3,400 feet in the San Mateo Canyon area, near San Onofre (Woodford, 1925; Southwick, 1928).
The sandstone of Eocene age in San Diego County is a source of plaster sand and specialty sands (see under "Sand and Gravel, and Crushed and Broken Stone" and "Specialty Sands" in the "Mineral Resources and Min- ing" section of the report).
Rose Canyon Shale (Upper Member La Jolla Forma- tion). The Rose Canyon shale is exposed in La Jolla Quadrangle and for a short distance to the north (Hanna, 1926a). The unit consists of gray to brown shale, mud-
stone, and siltstone, and has a maximum thickness of about 300 feet (Photos 1, 13, 28). In the northwest corner of the county, near San Onofre, a shale unit ;:bout 100 feet thick occurs between Eocene sandstone and San Onofre breccia, in a stratigraphic position similar to that of the Rose Canyon shale (Southwick, 1928).
The Rose Canyon shale is a source of common clay in the San Diego region (see under "Clay" in "Mineral Resources and Alining" section of report). The shale has been considered as a possible source of expansible shale (see under "Sand and Gravel, and Crushed and Broken Stone").
Poivay Conglomerate. The Poway conglomerate un- derlies irregular areas, which total about 70 square miles, in the center of the southwest part of the county (see PI. 1). The rocks are exposed in canyons and steep bluffs north of San Diego and underlie wide areas as low, elongate hills north-northwest and west of El Cajon Valley. From the eastern edge of the hills north of El Cajon Valley (Photo 15), a series of discontinuous out- crops of the conglomeratic gravels extend to the north- east as far as Whale Mountain, near Ballena. These out- crops probably are remnants of a filled stream channel, of probable Eocene or younger age (see under "Gold").
The Poway conglomerage consists of massive, poorly consolidated to well-cemented sandy conglomerate and conglomeratic sandstone, with small proportions of inter- bedded sand and shale layers (Photos 64, 65, and 68). Caliche is common in the upper parts of the unit, as noted by Hanna (1926a, p. 213-215). The clasts in the conglomeratic beds generally are rounded and range in size from pebbles to boulders, with an average size range of one inch to two inches (Bellemin and Merriam, 1958,
Photo 15. View northeast toward San Vicente Reservoir from point about 2 miles west of Foster. On ridges in foreground and middle back- ground is the Poway conglomerate, which in this area is as much as several hundred feet thick. It overlies granitic rocks of Cretaceous age.
30
California Division of Mines and Geology
p. 208). The clasts are composed chiefly of silicic meta- volcanic rocks, a small proportion of quartzite, and a very small proportion of granitic, rocks. The matrix of the conglomeratic units is sand, silt and clay.
As the unit probably was laid down over irregular terrain, its thickness probably varies greatly. A well drilled at the upper end of San Clemente Canyon passed through 875 feet of conglomeratic material (Ellis and Lee, 1919, p. 68). The thickness of the unit is estimated by Milow (1961), however, as about 450 feet.
The Poway conglomerate was first dated as Eocene by Hanna (1926b). This date was verified by the work of Cushman and Hanna (1927), Dusenbury (1932), Cush- man and Dusenbury (1934), and Stock (1937, 1938). The origin of the unit was discussed by Bellemin and Merriam (1958).
The Poway conglomerate is the source of much of the sand and gravel produced in the San Diego region (see under "Sand and Gravel, and Crushed and Broken Stone"); and the conglomeratic gravels of the Ballena area once were the source of a small amount of placer gold (see under "Gold").
Intrusive Dacite and Latite of Eocene Age or Younger
Intrusive volcanic rocks of Eocene or younger age are exposed beneath a total area of less than one square mile at three localities in the northwest part of the county: four miles east of Carlsbad (Cerro de la Calavera); three miles west of Bonsall (Morro Hill); and eight miles east of San Onofre.
Cerro de la Calavera is a hill composed of dacite which is part of a volcanic neck (Larsen, 1948; Larsen and Switzer, 1939). The body intrudes sandstone of Eocene age.
Morro Hill is composed of dacite and is a part of a volcanic neck which intruded granitic rocks (Waring and Waring, 1917; Larsen, 1948). Several adjacent out- crops are composed of associated flow and pyroclastic rocks.
At the locality eight miles east of San Onofre a small intrusive body of andesite or quartz latite is exposed which cuts Cretaceous sedimentarv rocks (Larsen, 1948, p. 111).
Crushed stone has been produced from the dacite which composes Cerro de la Calavera (see Calavera Rock Company in tabulated list under "Sand and Gravel, and Crushed and Broken Stone").
Miocene Rocks
San Onofre Breccia. In San Diego County the San Onofre breccia is exposed as a narrow belt, two miles and less in width, which extends southeast along the north part of the coast, from San Mateo Canyon, near San Onofre, to a point midway between Oceanside and Carlsbad. The breccia overlies sandstone of Eocene age, and adjacent to the coast is overlain partly by terrace deposits of Quaternary age. The rocks were described in detail by Woodford (1925) who postulated that the sediments composing the breccia were derived from the
Photo 16. San Onofre breccia in north wall of pit of H. W. Rohl Company sand and gravel operation, Oceanside. Photo by Thomas E. Cay, Jr.
west and deposited as a fanglomerate. The unit consists of poorly sorted, poorly to well-consolidated sandy breccia and sandy conglomerate, with a minor propor- tion of sand layers (Photo 16). The clasts are mainly varieties of schist whose main constituents are quartz and blue to green amphibole (including varieties of actinolite, crossite, and glaucophane). The breccia of the northern two-thirds of the belt is more consolidated than that of the southern one-third, and comprises a group of prom- inent hills; the rocks in the southern part are poorly con- solidated, thus are mainly eroded, and are overlain nearly wholly by terrace deposits. The steeply dipping section in the San Onofre Mountain area appears to be 4,000 feet or more in thickness. The San Onofre breccia was named and dated as Miocene by Ellis and Lee (1919).
At one locality in Oceanside, the San Onofre breccia is mined for use as sand and gravel (see "Sand and Gravel, and Crushed and Broken Stone").
Monterey Shale. An area of one square mile or less in the northwest corner of the county is underlain by Monterey shale composed of diatomaceous and cherty shale, and layers of hard sandstone (Woodford, 1925; South wick, 1928). It is also exposed in the sea cliffs south- east of San Onofre. The Monterey shale is Upper Mio- cene in age.
Miocene-P/iocene Rocks
Capistrano formation. The Capistrano formation is exposed in the county only along its northwest boundary, on the northwest side of San Mateo Canyon. The unit is composed of sandy shale and sandstone, and is believed to be either Miocene and/or Pliocene in age (Woodford, 1925, p. 216-217).
Pliocene Rocks Undivided
Nearly flat-lying sandstone of Pliocene age, which overlies unconformably rocks of Eocene age and older, is exposed widely from the south side of Mission Valley to the Mexican border. The sandstone is fine- to medium-
1963]
San Diego— Geologic Features
31
Photo 17. Table Mountain, northeast of Jacumba. Volcanic flow and pyroclastic rocks overlie con- glomeratic sandstone which overlies granitic rocks. View northeast. U.S. Highway 80 in lower middleground. (See also photo 18.)
Photo 18. Table Mountain, about 3' .'? miles northeast of Jacumba. Volcanic flow and pyroclastic rocks of probable Miocene age overlie conglomeratic sandstone which is underlain by granitic rocks of Cre- taceous age which contain a large proportion of metamorphic rocks. View north.
r a JQ.9£ .--■-' ^T—. c s
idesite -~i^
to I us. 'J^"1-^ -conglomeratic ss.
up
32
California Division of Mines and Geology
[County Report
grained, pale gray to pale yellowish brown, and contains a small proportion of siltstone layers. A bentonite layer that is widespread in the Otay Valley area can be traced almost to Mission Valley (Cleveland, 1960) (Photo 26). These rocks have a total thickness of about 1,250 feet, according to Hertlein and Grant (1954, p. 60). They were named the San Diego formation by Dall (1874). Later paleontologic work by Orcutt (1889), Dall (1898), Arnold (1906), Kew (1920), Hertlein (1929b), Grant and Gale (1931), Hertlein and Grant (1944), and others, has established the age as Pliocene.
Rocks similar to those described above, and of prob- able Pliocene age, are exposed discontinuously between Cardiff-by-the-Sea and Oceanside. At San Onofre, quartz sandstone of Pliocene age has been named the San Mateo formation (Woodford, 1925; Southwick, 1928).
One locality in the City of San Diego formerly was a source of specialty sands (see "Specialty Sands" in "Min- eral Resources and Mining" part of report). The layer of bentonite formerly was mined in the Otay Valley area (see under "Clay").
TERTIARY AND OLDER QUATERNARY ROCKS OF THE SALTON BASIN
Tertiary and older Quaternary rocks are exposed in the Salton Basin along the eastern edge of the county (see PI. 1). These' have been mapped and described by Dibblee (1954, p. 21-28), from whose work most of the following information was compiled.
Tertiary System
Miocene Rocks
Split Mountain Formation. The Split Mountain for- mation is mainly a gray, basal conglomerate which rests on a surface underlain by granitic and metamorphic rocks. The rocks crop out over an area of several square miles in the Split Mountain area, which is south of Oco- tillo Wells, and in a small patch of less than one square mile in the Santa Rosa Mountains. The unit is composed mainly of fanglomerate, sandstone, and breccia, and ranges in thickness from 0 to 2,700 feet (Dibblee, 1954, p. 22).
Alverson Andesite Lava and Associated Pyroclastic and Sed'nnentary Rocks. The Alverson andesite lava, which was named by Dibblee (1954) from exposures in Im- perial County, is exposed in the area north of Dos Ca- bezas (Photo 46) and at a locality near the mouth of Rockhouse Canyon. The rocks in these areas very closely resemble volcanic rocks in the Jacumba area, which have been called the Jacumba volcanics (Miller, 1935b; Brooks and Roberts, 1954) The andesite lava occur- rences at both Rockhouse Canyon and the Jacumba area (Photos 17, 18) are underlain by basal beds of conglom- eratic sandstone. Thus the Rockhouse Canyon outcrop, and perhaps the outcrops north of Dos Cabezas, may be remnants of flows which once extended northward from Jacumba for several fives of miles.
The layer of reddish tuff that underlies the volcanics is a source of crushed stone (see under "Sand and Gravel, and Crushed and Broken Stone").
Fish Creek Gypsum. A relatively extensive deposit o gypsum occurs along the border between Imperial anc San Diego Counties at the west side and northwest enc of the Fish Creek Mountains (Photo 46). Of severa square miles underlain by gypsum, only a very small pari is in San Diego County. The most northerly exposure in the area is overlain by a few remnants of a layer of celestite (strontium sulfate).
See also under "Gypsum" and "Strontium" in the "Mineral Resources and Mining" part of the report.
Miocene-Pliocene Rocks
Imperial Formation. The Imperial formation, which was named by Woodring ( 193 1 ), is exposed in San Diego County: (1) immediately south of Split Alountain, within an area of slightly more than 10 square miles; (2) north of Ocotillo Wells, in outcrops of less than one square mile; and (3) in the Coyote Mountains. At Split Moun- tain the unit is about 3,500 feet thick. The formation is composed of clay with a minor proportion of inter- bedded sandstone.
The Imperial formation in San Diego County is a pos- sible source of common clay (see under "Clay").
Cavebrake Conglomerate. The Canebrake conglom- erate underlies several tens of square miles in the eastern part of the county, principally in the following areas: on the east flank of the Santa Rosa Mountains; north- west of Coyote Mountain; on the southeast slopes of the Vallecito Mountains; and at the west end of the Coyote Mountains. The unit was named by Dibblee (1954, p. 23), who described it as "the coarse marginal conglom- erate facies of the Palm Spring and Imperial formations." The rock ranges in composition from fanglomerate to pebble conglomerate and is composed mainly of granitic detritus (Photo 24).
In the Santa Rosa Mountains the Canebrake conglom- erate contains veins of calcite which have been mined. The calcite has been used in the optical systems of gun- sights (see "Optical calcite").
Truckhaven Rhyolite. A thin wedge of rhyolite, named the Truckhaven rhyolite by Dibblee (1954), crops out about 4|/2 miles directly south of the northeast cor- ner of the county.
Pliocene Rocks
Palm Spring Formation. The Palm Spring formation (Woodring, 1931) is exposed over several tens of square miles in San Diego County, mainly along the east sides of exposed parts of the Canebrake conglomerate, which in part is the torrential facies of the Palm Spring forma- tion (Dibblee, 1954). The unit is composed of continen- tal sandstone and reddish clays, and grades downward into the Imperial formation. It is Pliocene in age.
Borrego Formation. The Borrego formation (Tarbet, 1944) was mapped by Dibblee (1954) as the lacustrine facies of the Palm Spring formation, and in the Borrego Badlands grades downward into that formation. The unit is composed of light-gray claystone and interbedded sandstone.
1963
San Diego— Geologic Features
33
Upper Tertiary and Lower Quaternary Systems Undivided Pfioeene-P/eisfocene Rocks
Ocotillo Conglomerate. The Ocotillo conglomerate (Dibblee, 1954) unconformably overlies the Borrego plays in the Clay Hills area and in the area north of Oco- tillo Wells. The unit is a gray, granitic-pebble conglom- erate (Dibblee, 1954, p. 74).
Brawley Formation. The Brawley formation is "the lacustrine and continental basinward facies of the Oco- tillo conglomerate" (Dibblee, 1954, p. 24). It is chiefly claystone with interbedded sandstone and conglomerate.
QUATERNARY ROCKS OF THE COASTAL PLAIN AND PENINSULAR RANGE PROVINCE, AND YOUNGER QUATERNARY ROCKS OF THE SALTON BASIN
Quaternary System
Pleistocene Rocks
Basaltic Flows. Basaltic flow rocks cap granitic rocks along the extreme north edge of the county, northwest of Deluz, and extend eastward into Riverside County (Larsen, 1948, p. 111-112).
Terrace Deposits and Dissected Alluvium. Pleistocene terrace deposits of marine and nonmarine origin are common along the coast of San Diego County, especially in the San Diego region, where the deposits overlie sedi- mentary rocks of Eocene and Pliocene age. The deposits generally are very thin and are composed of poorly con- solidated to unconsolidated, and poorly sorted to unsorted aggregates of silt, sand, pebbles, cobbles, and a minor proportion of boulders. The most widespread of these deposits comprise the Linda Vista and Otay marine ter- races, and lower, more seaward nonmarine deposits. The Linda Vista deposits contain reddish-brown pebbles which contain small proportions of iron oxide and phosphate (see under "Iron" and "Phosphates"). The Sweitzer for- mation is a terrace-like deposit of conglomerate which is common in San Diego and to the south, and has a maxi- mum thickness of about 65 feet (Goldstein, 1956).
Parts of the Otay, Linda Vista, and other terraces, and the floor of San Marcos Valley, consist of low mounds
Photo 19. Earthslide deposits in roadcut of Nigger grade, near Pauma Valley. Rock fragments are monolithic and composed of schist and gneiss.
which compose a gently rolling topography (Ellis and Lee, 1919; G. B. Cleveland, personal communication, 1958; personal observation, 1958). These are reported by Cleveland to have warped the landing strip at Brown Naval Air Station during wet periods.
Dissected alluvium and fanglomerate and nonmarine terrace deposits occur in the Pauma, San Jose, and Da- meron Valleys in the central part of the county and in the desert region in the eastern part of the county. These deposits range in composition from arkose to fanglomerate, and are composed of fragments which range from silt to very large boulders. Most deposits are poorly consolidated to unconsolidated and poorly sorted to unsorted. The deposits in the San Jose Valley region were correlated tentatively by Merriam (1959) with the Pauba formation mapped by Mann (1951) in the Te- mecula region.
Nonmarine terrace deposits in the San Diego region constitute a source of sand and gravel (see under "Sand and Gravel, and Crushed and Broken Stone").
Landslide Deposits. Landslide deposits composed mainly of angular fragments of schist and gneiss are widespread in the peninsular ranges and are especially abundant along the base of the steep, southwest-facing scarp of the Elsinore Fault (see Photo 19).
Lakebed Deposits. Lakebed deposits composed of gray to dark-gray mudstone, siltstone and sandstone underlie Pine Valley and a small valley at Harrison Park, south of Julian.
Recent Rocks
Playa Deposits. Playa deposits composed of fine silt- stone and mudstone underlie the following dry lakes in the eastern part of the county: Clark, Halfill, Bensons, and Blair Valley. None of these deposits is known to contain saline minerals.
Alluvium. River and stream channel deposits occur in western San Diego County and streambed deposits occur in the eastern part of the county. These are un- consolidated deposits composed mainly of clay-sized fragments, silt, sand and pebbles, with minor propor- tions of cobbles and boulders. Clasts generally represent various granitic and metamorphic rock types.
In the interior part of the county alluvium consists mainly of valley fill, which underlies many tens of square miles. In the eastern part of the county, flood plain and fan deposits slope outward from mountain ranges and merge with valley fill deposits.
Other types of alluvial deposits in the county include beach sand deposits, swamp (or bog) deposits in the upper coastal valleys, and sand dunes along the south- east side of Clark Lake.
As the rivers and streams of the county are dry, except for a few days each year, their bed deposits constitute sources and possible sources of sand and gravel. Of present value are chiefly river bottom deposits in the San Diego region which are major sources of sand and minor sources of gravel (see section on "Sand and Gravel, and
34
Palo mar Mt.
California Division of Mines and Geology
Volcan Mt.
[County Report 3 Mt. San Jacinto
Banner Canyon /
hyb
Goid^ Cross mine
Chariot Canyon \
Ba nner
San
Felipe
Valk
Ranchit vminc
——Golden Chariot mine
Photo 20. Aerial view north-northwest shows Julian gold mining district and vicinity. Trace of Elsinore fault extends diagonally across view in trough from point near left edge of skyline to lower part of right edge of photograph. Light-colored, boulder-covered slopes in lower right part of photograph are underlain chiefly by Bonsall tonalite (Kb); dark-colored rocks on steep slope at lower left are mainly underlain by Julian schist (fc j).
Photo 21. Julian area, view north. Banner Canyon in middleground, Volcan Mountain in background. Elsinore fault cuts through area along base of Volcan Mountain in Banner Canyon. Dump from gold prospect is in center of lower middle- ground.
1963
San Diego— Geologic Features
35
Crushed and Broken Stone"). A single peat deposit is known in the county (see under "Peat"). Beach and dune sands are a possible source of specialty sands (see jnder "Specialty Sands"). Pebbles for grinding and filtering once were recovered from beach deposits along the south coast.
STRUCTURAL GEOLOGY
A discussion of the structural features of the penin- sular ranges has been provided by Jahns (1954b, p. 41- 45); and a similar discussion of the Salton Basin, which includes the eastern part of San Diego County, has been written by Dibblee (1954, p. 26-27).
The dominating structural features of San Diego County are the northwest-trending fault zones which cut the north-central and eastern parts of the county. Of these, the principal zones are the Elsinore, Agua Tibia- Earthquake Valley, San Jacinto, and Santa Rosa (see PI. 1). The desert mountain ranges and hills have been elevated along these faults; and a complex folding of Tertiary sedimentary rocks, along the eastern edge of the county, also is associated with them. The fault traces are characterized by erosional depressions bordered by steep scarps, which generally face westward (Photos 5, 9, 20, 21, 22). Landslides are particularly prominent along the steep scarps of the Elsinore Fault Zone (Photo 21).
Maximum apparent lateral displacement of several miles is indicated for the rocks along the Elsinore Fault in the Covote Mountains region of San Diego and Imperial Counties. In this region, interlayered marble and schist of pre early late Cretaceous age at Dos Cabezas, about three miles south of the fault, very closely resemble similar rocks in the western and eastern parts of the Covote Mountains, less than one mile to several miles
north of the fault (PI. 1). These relationships, however, do not seem to readily indicate the direction of move- ment along the fault. To the northwest, in the Julian district, apparent right lateral movement of similar rocks along the fault is estimated to be about 2,000 feet.
Southwest of the Elsinore Fault Zone major faults are uncommon. An erosional depression that extends from McGinty Mountain east-southeast along Lyons Valley to Campo, suggests an extensive fault, but with small dis- placement.
Faults that contain hydrothermal mineralization occur mainly in the part of the county that lies southwest of the Elsinore fault. Gold-bearing quartz deposits at Ju- lian, and in the Laguna Mountains, occur in shear zones in schist; and similar deposits near Dulzura occur in a northwest-trending fault zone which cuts metavolcanic rocks. Quartz veins that contain tungsten, lead, gold and silver fill north-trending shear zones which cut schist at Metal Mountain, north of Buckman Springs. Copper and iron minerals occur in shear zones that cut metavolcanic rocks near Olivenhain, and in the San Mateo Canyon area at the north edge of the county.
MARINE GEOLOGY
Studies of the marine geology along the coast of San Diego County have been made by workers at Scripps Institute of Oceanography, at La Jolla. These studies have resulted in papers by F. P. Shepard with others (1940 to 1951) on beach erosion and sand movement; and by K. O. Emery with others (1941-1960) on the submarine geology of the ocean floor. For additional references see the bibliography on "Marine Geology" at the back of the text.
Photo 22. View southeast along steep west slope of Palomar Mountain, showing trace of Elsinore fault zone. Warner Valley and Lake Henshaw in background.
36
California Division of Mines and Geology
[County Report 3
MINERAL RESOURCES AND MINING
Many mineral commodities have been produced in San Diego County, but by far the principal ones in recent vears have been sand and gravel, and crushed and broken stone. The value of these commodities produced in 1959 constituted about 94 percent of the value of the total mineral output of the county. Other important commod- ities to be produced in recent years are dimension stone, salt, magnesium chloride, clay, pyrophyllite, and specialty sands. Important commodities produced in former years include gold (1870-1875, and 1887 to about 1900); gem minerals (especially tourmaline and kunzite; mainly 1900- 1912); feldspar (1918-1943); and lithium mica (1892- 1928).
HISTORY OF MINING *
The history of mining in San Diego County might be said to have started with the discovery of San Diego Bay by Cabrillo in 1542, for one of the purposes of such voyages as Cabrillo's was to find mineral riches for Spain. Cabrillo discovered only a beautiful harbor, however, and more than 300 years was to pass before a mineral deposit in the county would be worked commercially.
During the late 1700's and early 1800's, some non- commercial mining was done by the early Spanish settlers. These people recovered stone and adobe for construction of buildings, small dams, and walls. In addi- tion, salt was produced by evaporation of sea water in marshes along the edge of San Diego Bay at least as early as 1869.
During the 1840's and 1850's, emigrants from the east- ern United States passed into Southern California over several trails which crossed present-day San Diego County. These trails included the Butterfield Route to Los Angeles, via Vallecito, Warner Springs, and Oak Grove; the Kearney Route to San Diego, via Vallecito, Warner Springs and Ramona; and routes along the coast and the Mexican border, approximately following respec- tively the routes of present U.S. Highways 101 and 80. In addition, several United States government surveys during this period traversed the county. In spite of this activity, none of the gold deposits of the county was discovered and mined, although it is said that Indians and early-day Spanish and Mexican inhabitants recovered small amounts of gold from the deposits southeast of present-day Escondido.
In early 1869, San Diego was a small community of only a few hundred people, but one of these was A. E. Horton, a real estate promoter. During that year, the promotions of Mr. Horton, and news of plans to build a railroad from El Paso to San Diego, began to attract people to San Diego; and by the end of the year the town was booming. Perhaps this boom was at least partly responsible for the attraction of the prospectors who dis- covered placer gold in the central part of the present-day county in November 1869. These men were Mike and Webb Julian and James and Drury Bailey, ex-Confeder-
* This account was compiled from descriptions of mineral deposits in the text and tabulated list of this report and from many of the entries in the bibliography listed under "Mineral resources and mining."
ate soldiers attracted to the West following the economic collapse of the South at the end of the Civil War. About three months after the discovery of placer gold, on Feb- ruary 21, 1870, lode gold was discovered at a locality two to three miles east of the placer fields. On February 22, papers for the Van Wert and George Washington Claims were filed on the site, and in a small valley just south of the George Washington Claim a camp, soon to be named Julian, began to grow.
During the spring of 1870 people seeking gold came to the Julian area by the hundreds, and consequently the Owens, Helvetia and other deposits were discovered and developed. In addition, the search for more deposits in the area branched out. Thus, the Stonewall Jackson (Stonewall) Deposit— to be the most prolific mine in the county— was discovered in March at a point about seven miles south of Julian; and in August 1870 deposits were discovered along canyon slopes three to four miles south- east of Julian. Banner Camp arose in the canyon near these deposits, and subsequently the Bailey Brothers, Hubbard, and Golden Chariot Mines were developed. Thus, as the town of San Diego boomed so did the min- ing camps in the mountains to the east. By the end of 1870 an estimated 2,000 people lived in San Diego and a total of about 1,000 lived in Julian, Banner, Coleman City and other camps. In 1870 an attempt was made to have the government construct a mint at San Diego to coin gold from the hills, but this failed.
By 1873 the population of San Diego had risen to 4,000, and that of Julian and the other gold camps to perhaps 2,000. During that year the Democratic county conven- tion was held in Julian; Mike Julian was elected county assessor; and the citizens of Julian attempted, without success, to have the county seat moved from San Diego to their town. During 1873, the total value of gold shipped from the mining camps of the county rose to $500,000. But in December of that year, plans for the El Paso and Pacific Railroad collapsed, and the boom in San Diego was finished. During 1874, production of gold began to fall, and by the end of 1875 nearly all of the mines were idle. The population of San Diego had dropped to 1,500 or less by the end of 1874, and by 1876 probably less than 100 people lived in Julian. During the years from 1870 to 1875 the mines had yielded nearly $2,000,000 in gold, a small figure when compared to the production from the Mother Lode in Northern Califor- nia, but significant in the history of San Diego County.
The decade from 1875 to 1885 in the county was quiet. A new gold discovery was made at Dulzura in 1877, but this time no bonanza followed. Finally, however, in 1885, a railroad finally arrived in San Diego; and even though it was only a branch of the Santa Fe from Los Angeles, another boom began in the region. The population of the city rose to an estimated 40,000 during the boom's crest, which lasted from the summer of 1886 to February 1888, then dropped to 17,000 by 1890, after the boom had ended.
1963]
San Diego— Mineral Resources
37
Photo 23. Union Brick Company, Rose Canyon, showing famous leaning smokestack constructed in 1888. View north-noifhwest.
During this boom, mining was very active in the county. In 1887, stone was quarried for Sweetwater Dam —the first large dam constructed in the county. In 1886, Robert W. Waterman, Governor of California from 1887 to 1891, purchased the Cuyamaca Rancho and the inac- tive Stonewall Mine, which was at the north edge of the rancho (Photo 43). Waterman reopened the mine in 1887, and from 1888 to 1891 it yielded nearly $1,000,000 worth of gold. Waterman reportedly had paid about $75,000 for the mine. The success of this venture helped to create renewed interest in gold mining in other parts of the county. During the late 1880's and 1890's several mines were reopened in the Julian district, including the Owens and Helvetia (Photo 41); and several previously overlooked deposits in the district were discovered and developed. Also during this period, the Shenandoah and other deposits near Mesa Grande were worked; and the Cleveland-Pacific and additional deposits near Escondido were active.
During the late 1880's, the Waterman family also undertook two other important ventures. One was the planning of the San Diego and Cuyamaca Eastern Rail- road from San Diego to Cuyamaca, and by 1888 its con- struction to Foster, the ultimate destination. The other venture was the construction of the Cuyamaca Dam on the Cuyamaca Rancho and a flume to carry water from the reservoir the dam created to San Diego. The flume was dedicated in December 1889.
The construction of the railroad enabled a new phase of the mining industry to begin in the county— large- scale quarrying of stone. In 1888 the Simpson-Pirnie Company opened a quarry adjacent to the railroad south of Lakeside, and was to operate it until 1932. The com- pany quarried blocks of granite which were transported by rail to the company yard in San Diego where they could be processed and distributed for sale as riprap and rubble, later as paving blocks, and beginning in 1898, as polished monument and building stone. In 1894, stone
quarried from the Waterman Deposit at Foster was used to construct the jetty at the entrance to San Diego Bay. By 1900 several other dimension stone producers had begun to operate in the Foster-Lakeside area.
Also in 1888, a brick plant was constructed in Rose Canyon adjacent to the Santa Fe Railroad. A stack was built on the property which, until it fell recently, was referred to as the "leaning stack" of the Union Brick Company, which moved to the site about 1912 (Photo 23). In 1889 a cement plant to be built on the Jamul Ranch was being planned by the Jamul Portland Cement Company. The company began production in early 1891, but operated only for a few months. The company's product is said to have been unable to compete with portland cement being shipped to San Diego from Eng- land by water. In addition, by then the prosperous effects of the boom of 1886-1888 had ended. This attempt was only the second to produce portland cement in Califor- nia. The remnants of the kilns still stand (Photo 52).
After the boom of the late 1880's, prospecting for gold was carried on in many parts of the county. The Rice brothers and others prospected in the Montezuma dis- trict; the Donahoe brothers and others worked deposits in the Dulzura district; the Noble brothers and other men worked deposits m the Laguna Mountains, and in the Deer Park and Boulder Creek districts; activity in- creased near Escondido; a Mr. Campfield prospected for lead, silver, and gold on Metal Mountain, north of Live Oak Springs; and placer gold deposits near Ballena were worked. None of these ventures, except possibly that of the Noble brothers, was economically successful, how- ever. In 1893, after Waterman had died, the Stonewall Mine was closed, probably not to be opened again. But by then it had yielded the largest total value of gold of any mine in the county— about $2,000,000.
In the 1890's, as gold mining declined, the mining of minerals from pegmatite deposits began. In 1892 produc- tion of lithium mica (lepidolite) began at the Stewart
38
California Division of Mines and Geology
[County Report 3
Deposit near Pala. In the late 1890's gem mining was in- troduced with production of gem-quality tourmaline and spodumene from deposits near Pala, and tourmaline and other minerals from the remarkahle Himalaya and other deposits near Mesa Grande. Deposits near Ramona, Rin- con and in other areas also were being worked, and yielded small quantities of gems. The deposits were mined most ambitiously from about 1901 to 1912, and between 1902 and 1910 yielded about $1,300,000 worth of gem minerals. The production of gems dropped con- siderably after 1911, with the fall of the Chinese dynasty that had favored tourmaline as a gem stone, and with a corresponding drop in prices.
As the population of the county gradually increased during the early 1900's, production of sand, gravel and stone, for use in construction, also increased. Several of the present-day rock product companies began opera- tion during this period, including the Jamacha Sand and Gravel Company in 1906, and the Mission Rock Com- pany (now part of the Daley Corporation) in 1913.
During the period before World War I, from 1910 to 1915, mineral production was relatively low. During this period, also, several wells were drilled along the coast in an unsuccessful search for petroleum. In 1912, the Union Brick Company moved from downtown San Diego to its present location in Rose Canyon. During the mid-19 10's production began of magnesium salts from sea water bittern, but in 1916 both the salt and mag- nesium chloride operations at the south end of San Diego Bay were washed out by the flood caused by the break of the Otay Dam. The salt works was rebuilt soon, but magnesium salts were not produced again until late 1919 or early 1920, when the California Chemical Company resumed the operation.
During the years 1917 to 1919, when the United States was most affected by World War I, mineral production increased several fold in the county, mainly because of production of potash (see Table 1 and Figure 3). During the war, foreign sources of potash to the United States were cut off, its price increased about ten-fold, and pro- duction of the commodity from kelp was made econom- ically possible. About $3,400,000 worth of potash was produced in the county from 1916 to 1919, of which nearly $3,000,000 was produced by four companies from 1917 to 1918. Also during the war, foreign sources of pebbles used in grinding mills were cut off, and pro- duction of these from beaches of San Diego County started in 1915, and was to continue until 1949. A rise in the price of copper, from about 13 cents per pound in early 1914 to about 27 cents per pound by 1916, enabled two small copper deposits in the county to be worked between 1915 and 1919. These were shut down in 1919 when the price returned to normal. In 1917, small quan- tities of molybdenum, strontium minerals, and possibly tungsten also were mined in the county. From 1918 to 1920, the Stewart Mine reached its maximum yield of lithium mica, and in 1918 feldspar was first produced in the county.
spending Building boom Sand. J
grovel ond stone production \ increase tremendously /
Growth of populot. from census of I9l0 ond i960
1920,1930,1940,
„ SB,
";
rid War" yrj
A
TION
PRODUCTION^
^A
^^
\ Economic J
Figure 3. Graph comparing yearly value of mineral production of Son Diego County with growth in population, 1910 to 1957.
In the early 1920's, after a brief economic letdown fol- lowing World War I, the population and mineral produc- tion of San Diego County continued to grow. By then metal mining had almost stopped, but large tonnages of sand, gravel and stone, and other non-metallic minerals were being produced. The production of clay became significant, when in about 1919 Standard Oil Company of California and General Petroleum Company began to produce bentonite from deposits near Otay, for use in petroleum refining, and Pacific Clay Products began working a deposit near Carlsbad.
In 1921, a predecessor of Standard Sanitary Manufac- turing Company began to mine feldspar and quartz from a deposit near Campo. The company constructed a mill to process the rock mined at a site adjacent to the San Diego and Arizona Eastern Railroad (Photo 32). This railroad had been completed in 1919, to at last link San Diego and the Imperial Valley. The deposit was to be the principal source of feldspar in California from 1921 through 1942. Other feldspar producers also began opera- tion in the county during the early 1920's, and gem min- ing continued on a small scale. In 1923, Nelson and Sloan began production of sand and gravel on the Otay River
1963
San Diego— Mineral Resources
39
I.IOO.OOO
i.OOO.OOO
/
/
800,000
600.000
G'o«th of p from ein*u( 1940,1950,0
Ol 1910,1920,1930,- >d I960
I
/confl.
; /
Tonn
grove
9«
lz',:z— 1
y&. /
Z 00.000
7
,/
-^ZJy~
\ 08
"**«2__y
Figure 4. Graph showing relationship between yearly production of sand and gravel in San Diego County and growth of population.
bed. At this time, also, Fenton-Sumption-Barnes merged with the Independent Stone Company to become Fenton- Parker Company (which was to be renamed H. G. Fen- ton A4aterial Company in the early 1930's). From 1921 to 1923, marble for buildings and monuments was quar- ried from the Verruga Deposit near Ranchita. During the early and mid-1920's several more wells were drilled unsuccessfully for oil. In 1923 the California Chemical Company of Chula Vista was purchased by National Kellestone Company and was known thereafter as the California Chemical Corporation. This corporation began to produce bromine, in addition to magnesium chloride, in 1926.
During the mid- and late-1920's production of sand and gravel, dimension stone, and clay reached remarkable heights (see Table 1 and Fig. 3). In 1928, Crystal Silica Company began production of high quality quartz sand from a deposit near Oceanside. But this was the last year in which lithium mica was produced from the Stewart Deposit. In 1929, V. R. Dennis' Canyon Rock Company began operations at its present site north of Grantville.
With the beginning of the depression in 1929, mineral production of the county dropped markedly and con- tinued low through the 1930's (see Fig. 3). In 1932, the Simpson-Pirnie Company, which had produced dimen-
sion stone continuously in the county since 1888, stopped operation. During the 1930's, gold mines were reactivated at Julian, but generally with little success. Small gold deposits south of El Cajon were worked; and from 1939 to 1942 several deposits south of Pine Valley were worked for gold with minor success. In 1937, the Beryllium Alloys Company began to develop a supposed large beryllium-bearing deposit near Vista, but no ore was mined. Also in 1937, Caudell and Johnson began producing sand, gravel, and stone in the San Diego re- gion, and the operations of the California Chemical Cor- poration at Chula Vista were taken over by Westvaco Chlorine Products Corporation.
During World War II, as during World War I, mineral production rose sharply in San Diego County. During World War II, the rise in production was caused mainly by the increased output of sand, gravel and stone for use in military construction in the coastal area. Tungsten also was produced, between 1941 and 1945, from the Pawnee and other deposits; strontium minerals were produced at the Roberts and Peeler de- posit, south of Ocotillo Wells; molybdenum ore was mined briefly at the Lippner Deposit at Campo; and optical calcite for use in gun sights was mined at the Hilton Deposit on the east side of the Santa Rosa Moun- tains. In 1942 the Pacific Feldspar Mine near Campo was shut down, reportedly because the operator could not compete in wages with the U.S. Army which hired civil- ians to work on a military base at Campo. In 1944, the Friday nickel-bearing deposit near Julian was investigated by the United States Government as a possible source of nickel, for use at the newly completed Kaiser Steel Plant at Fontana, but the deposit was found to be too small.
Near the end of the war, military construction ceased, and in 1945 mineral production dropped markedly. Sub- sequently, however, as the population of San Diego and environs continued to grow, housing and other construc- tion were needed. Consequently, output of sand and gravel rose from only 475,000 tons in 1945 to more than 4,000,000 tons in 1954 (Fig. 4). By that year both civilian and military construction were consuming large amounts of these commodities. In 1945 recovery of pyro- phyllite began from deposits near Rancho Santa Fe, and production of crushed stone for use as roofing granules began from deposits near Rancho Santa Fe and in the southeast part of the county. In the late 1940's, a small quantity of peat also was produced.
From about 1950 to 1956, a government purchase program for tungsten stimulated development and mining of several such deposits in the county, including the Pawnee and Payoff. During the early- and mid-1950's, uranium prospecting also was popular in the county, but only radioactive minerals in pegmatite deposits were found, and no ore was uncovered. During the mid- and late-1950's large quantities of broken stone was being used for construction of both civilian and military sea front projects, including the Mission Bay Park. Gem minerals also were produced in the county
40
California Division of Mines and Geology
[County Report 3
Tab le 1 . Recorded Mineral Production of San Diego County
1880-1959 '
Gold" (Value)
Silver1 (Value)
Gem
minerals1 (Value)
Feldspar1. *
Salt1. 2'
Clay and clay products
Copper and
tungsten (See below)
Lepidolite and am-
blygonite,
pyrophyllite
(See below)
Bentonite13
Pottery clay
Brick1'
Year
(Tons)
(Value)
(Tons)
(Value)
(Tons)
(Value)
(Tons)
(Value)
(M)
(Value)
1880s
"$81,558 60,000 100,000 50,000 65,000 95,125 140,450 66,900 s160,000 '275,440 '11,620 '25,460 '62,900 68,140
37.160
1,120
62,000
72,680
72,860
28,680
63,040
65,840
26,940
34,140
79,700
6,780
340
7,455
6,920
12,812
24 24
1881s
1882«
18836
"$5,000
5,000
2,000
78,758
198.537
192.000
25,740
30
1884s
18856
1886s
1887s
18886
1889s
1890
1891
1892
1893
1894
Lepidolite and amblygonite2' 23
700 700 600 650 600 600 600 1.050 7,900
11,23. 2V$5,000
5,000 4,800 5,850 5,000 5,000 4,000 9,600 7,900
1895
1896
30
1897
Copper1
(Tons)
(Value)
1898
650
850
750
1,150
700
2,150
3,800
3,200
3,950
4,450
2,100
5,850
8,800
9,500
10,500
9,400
5.450
1,250
4,000
'. ». 232,700
1899
'4,300
1900
990 980
15
3'7,460
550
100
35
86
1,721
Pounds
Value
2'$500
20,000
150.000
100,000
136,000
66,000
284,500
206,300
121,500
125,000
110,300
25,000
12,500
7,500
1,500
2,450
2,700
8 8
2,100
1,405
400
8,550
1,900 9,400 4,000 3,500 1,700 2,210
8 8 8
8
8 8 8
8
8 8
8
1,200 1,400 800 50 800 600 50
■°. 23$29,000
37,500
31,900
100
16,000
9,500
700
'3,250
1901
'5.800
1902
'3.450
1903
'11,150
1904
"104,477 4,808
$14,627 750
'23,700
1905
'28,350
1906
6,000
7,000
7,000
15,000
8,000
13,000
12,450
20,500
15,300
17,600
4,500
10,650 12,400 15,300
16,000 13,000 17,000
25,000 27,000 25,000 12,000 22,000 27,000 27.000
37,600
5,000 55,000 60,000 60,000 24,000 37.500 31.350 51,750 46,200 19,600
8
9,750
61,700 52,800 77,100
2'96,000 60,000 115,000
100,000 100.000 120,000 60.000 80,000 100,000 110,000
150,400
8
125,000 150,000 120,000 125,000 120,000 135,000
130,000 150,000 120,000
200,000 210,000
210,000 210,000
'34,900
1907
13,246
2,659
36,400
1908
16,700
1909
38,950
1910
62,650
1911
120
2,000
68.000
1912
400 850
500 2,850
80,000
1913
30
500
68,400
1914
1,364
9
30
3,008 16,806
153,349
4,143
4
526
4,134
43,502
1,023
8
56,400
1915
90
70
880
4,110
800
10,080
700 670
1,400 1,000
8,800
74,000
14.400
153,500
10,600 10,200
21,000
1916
300
600
8. 29
36,850
1917
8
700
»$3,600
21,400
1918
29,100
1919
1,470
12
2262,930 57.500
2292,600
22.2893,050 29.50101,000
2936,950 2966,450 2958,250 31,750 63,900 34,000 25,800
15,500
8
8 B 8 8 8 8
8 8 8
12,250 15,200
12
1920
2,950
1,850 3,500 6,100
6,850 5,800 7,000 9,000 12.850 11,500 4,450
4,150
2,500
1,000 1,650 3,250 3,400 2,650 1,350
1,800 2,150 2,750
2,100
17,700
11,100 29,500 42,800
47,950 40.600 54.000 72,000 82,300 69,600 31,400
54,600
27,450
14,200 16,400 21,850 24,700 11,700 6,650
10,000 11,500 15,000
11,000
5,850
87,600
1921
8 8
822
4,830 5,134 10,543 11,490 2,671 1,282 2,234
3,988
5,573
5,894 25,514 10,367 2,170 2,100 3,080
14,630 16,975 10,535
245
8 8
144
97 58 340 92 13 5 10
15
32
24 187 65 12 14 20
166 128 36
2
12
1922
8
8
8
8 8
69,650 47.750 78,950 55,700
69,000
8
4,200 9,800 5,900 2,600 3,100 2,000
5,400 2,100 4,500
8 8
12
1923
5,600
12.800 27.000 30,200 16,200 33,400 20,150 15,500
11,400
8
1924
110
2,300
232,100
1925
119,200
1926
8
40 500 400
1,000 12,500 16.000
230,500
1927
7,400 5,500 8,400 5,300
6,400
165,200
1928
101,500
1929
146,200
1930
8
1931
79,600
1932
8
1933
35,000 40,000 34,000 34,500 32,000 37,000
34,500 40,000 32,000
45,000 50,000
52,000 53,000
500 2,600 1,400 600 900 600
1,100
600
4,100
8
1934
8
24,500
1935
8
1936
8
1937
8
1938
7,023
688
8
Tungsten ore
1939
(Units)
(Value)
8
1940
8
1941
8
8
1942
9,900 18,700
8
1943
Pyrophyllite1
70
1
Pottery clay and bentonite
(Tons)
(Value;
13
10,800 100
10,500 300
1944
8
1945
8
1963]
San Diego— Mineral Resources Table 1. Recorded Mineral Production of San Diego County— Continued
41
Pebbles for grind- ing (and filtering)28
Stone
dimension3
Stone, crushed and broken1 • '•
Sand and gravel'. *
Unapportioned and miscellaneous1 -n
Total yearly value
(Tons)
(Value)
(Cu. ft.)
(Value)
(Tons)
(Value)
(Tons)
(Value)
(Value)
(Description)
Year
1880s .*
18816
1882s
1883s
1884s
1885s
1886s
1887s
1888s
1889s
1890
1891
1892
1893
11,10.23.7149.400 '25.000
'3,600 '23,400
'5,400 '18,200 '14,400
'6,900 '14,200 '42,600 '200,200 '16,500 '49,400
28,500
37,100
33.500 147,800 138,700 148,600 130,600 133,000
84,400 130,900
103,500
98,500
41,800
205,400
"187,900 60,400 127,900
72,100 123,600
51,200 215,400 105,300 267,600 238,600
52,600
40,800
126,500 64,700 28,900 39,500 57,100 57.500
46,100
71,400
449.300
247,700 213,900
110,200 241,200
$2,250
2393,800 31,100 70.400 101,900 90,800 65,600 125,100 169.000 247,600 201,600 485,500 138,700 385,200 372,100 252,300 486,600 344,800 334,000 288,400 301,000 314,400 211,400
398,100
1.713,600
1,941,600
343,200
794,200 492,200 647,600
815.200 987,000 1,108,700 1,218,000 1.567,900 1,772,800 1.447,300
1,303,000
853,600
376,000 625,100 487,300 471,400 585,200 594,500 535,700
627,700 847,200
1,416,500 1.439,000 1,665,700
1,995,500 1,142,700
1894
1895
1896
1897
6,600 11,000 7,300 13,900 20,600 10,800 7,800 9,500 9,500 19,900 9,000
16.23. n$4,850
"8,150
"9,900
"22,400
"13,200
"'13,550
"■'7,850
"'10,250
"■'10.250
"23,650
"10,000
15 15 15
"2.200 "21.700 "6.400 "8.300 "8,300
"6,150
"9.200 15,200 7,850
22,400 35,700 40,600
76,500 108,700 45,300 "'63,100 47,600 28,900 27,400
"11,400
9,700
10,100 11,200 10,600 28,000 29,000
8 8
14,200 15.400
8 8
43.900 85,900
1898
1,317
Lead (31 000 pounds)9
1899
1900
1901
1902
1903
1904
1905
1906
12,052
Lead (971 pounds, $52); Marble (4,000 cu. ft., $12,000)
1907
1908
214,600
1909
1910
77,200 25,800 37,400 186,100 120,700 58,200
53,000
107,300 290,700 128,400
«.2'$62,800 "13,300 "17,700 70,900 "71,000 "33,000
"22,300
"85,600
100,200
"128,500
4
"295,400 "216,000
"307,000 "385,000 "478,400 "674,300 "1,179,500 "509,900 413,300
358,400
146,900
248,300 148,200 169,200 274,300 255,800 "227,700
"312,500 "479,500 "679,500
"574.200 "1,082,900
"1,519,300 "404,600
1911
2,200 18,300 5.400 6,900 6,900
5,500
5,600 6,700 2,500
8,500 15,900 19,700
26,800 28,500 16.300 18,900 14,200 15,800 10,000
4,700
6,200
5,300 6,300 6,200 14,100 10,900
1912
1913
1914
33
13
33
33
19,303 18,000
33 33 33
33
33 S3
33
33
2*1,100
130
170
8
44 23 16
1,350 2'180,650
211,498,200
1,578,850 2154,400 2157,000
70,150
62,190
22162,400
105.300 150,600 164,500 188,900 44,600 2'207,600 21.22398,450
2'57.950
21145,500
21.2290,850
2136,800
2'. 22104,500
21 . 2288,900 2L 22115,700
2L 22103,100
22108,900 2L 22101,400
2'. 22121,700
2'.22393,100 2'. 22143,600
2'. 22100,200 2'.22198,500
1915
Potash (2,150 T, $175,800), mineral water, salt, strontium
1916
Potash (5,250 T, $1,492,100), pottery clay, gem minerals, min- erals, mineral water, molybdenum, glass sand, silver .. .. Potash (10,392 tons)
1917 1918
2.600
Copper, gem minerals, mineral water, potash, quartz sand
Quartz sand (7,557 T, $18,900). magnesium salts, mineral
1919
2,100
1920
Quartz sand ($750), gold, magnesium salts, marble, silver
Bentonite, gold, magnesium salts, marble, quartz sand, silver__
Bentonite, brick and tile, lead, magnesium chloride, marble,
quartz ...
1921
268.500 219,500
323.900 539,200 689,600 946,200 1,867,900 781,800 497,600
316,700
184,200
310,800 167,600 195,400 261,300 298,800 283,000
368,900 556,700 709,000
470,600 1.058.000
1,726,000 475,900
1922
1923 1924
Bentonite, lime, magnesium chloride, quartz sand.
Bentonite, bromine, copper, lead, magnesium chloride, zinc. _ Bromine, heptane, magnesium chloride, paving blocks.
Bromine, magnesium chloride, quartz __ __ .
Bromine, magnesium chloride, mineral water, quartz sand
Brick and tile, bromine, gem minerals, magnesium chloride,
1925
1926 1927
150
1929
15
1930
21
Bromine, gem minerals, magnesium chloride, mineral water,
1931
Bentonite, brick and tile, bromine, pottery clay, gem minerals, magnesium chloride, mineral water, pebbles for grinding,
1932
4
Brick and tile, bromine, pottery clay, gem minerals, magne-
1933
iy*
Bromine, pottery clay, copper, magnesium chloride, mineral water, quartz _ __
1934
VA
Brick and tile, bromine, pottery clay, gem minerals, lead
(8,323 lbs., $333), magnesium chloride, mineral water, quartz
Brick and tile, bromine, pottery clay, gem minerals, magne-
1935
1936
Brick and tile, bromine, pottery clay, gem minerals, magne-
1937
Brick and tile, bromine, pottery clay, gem minerals, magne-
1938
Brick and tile, bromine, pottery clay, gem minerals, magne- sium chloride, mineral water, quartz, dimension stone_ Brick and tile, bromine, pottery clay, gem minerals, magne-
m
22
500
500 100
1,300 2,200
6,000 7,200
1939
1940
120
Brick and tile, bromine, pottery clay, gem minerals, magne- sium chloride, mineral water, quartz, strontium minerals,
1941
63
Bentonite, brick and tile, bromine, magnesium chloride, min- eral water, quartz, dimension stone, strontium minerals
Bentonite, brick and tile, bromine, magnesium chloride, min-
10
1942
12,600 28,300
1943
151
Brick and tile, bromine, magnesium chloride, mineral water,
1944
225
Brick and tile, bromine, magnesium chloride, mineral water, pyrophyllite, quartz sand, strontium minerals2' __ _
1945
42
Table 1
California Division of Mines and Geology [County Report 3 Recorded Mineral Production of San Diego County— Continued
1880-1959 '
Gold'
(Value)
Silver1 (Value)
Copper and
tungsten (See below)
Gem minerals1 (Value)
Feldspar1-26
Lepidolite and am- blygonite. pyrophyllite (See below)
Salt1 .2'
Clay and clay products
Bentonite13
Pottery clay
Brick"
Year
(Tons)
(Value)
(Tons)
(Value)
(Tons)
(Value)
(Tons)
(Value)
(M)
(Value)
1946
70
455 280
105
1,925
8
8
8
8
8 19 19 19
8
8
$7,300 8 8 8
54,000
220,000
8
8
8
8 8 8 8 8
8
8
8
8
8
3,600
11,300
8 H
u u
»!!
14 14 14 14
14
14 14 14 14
5 3
2
11
All clay
1947
13
14,550 35,200
21,100
29,100 33.800 34,100 28,500 26,300
22,100
40,700
"15,000 "60.900
17,500
21,800 25,400 26,600 21.400 13,200
22,100
40,700
8 8
8
1948
1949
1950
1951
1952
1953
B
175
»
8 8 8 8
8 8
145
10 tons
"$9,100 38,500
6 6
1954
1955
8 8 8 8 8
1956
3,000
1957
8 8
8
1958
1959
1 Most of the statistics in this (able are from (1) reports generally titled "California Mineral Production" of the California Division of Mines (;md its predecessors, the California Mining Bureau and the California Division of Mines and Mining) and (2) files of the U.S. Bureau of Mines and the California Division of Mines. Statistics in published reports were collected and compiled by the Division of Mines (and its predecessors) prior to 1946 and by the U.S. Bureau of Minis after that year. Statistics for gold and silver produced in the enmity were first collected in 1880; statistics for most other commodities were first collected in 1804.
statistics from California Division of Mines Special Report 7A. "Gem- and Lithium- bearing Pegmatites of the Pala District. San Diego County, California," by R. H. Jahns and L. A. Wright.
3 Statistics are mainly from (1) California Division of Mines Special Report 3, "Com- mercial Black Granite of San Diego County. California," by R. A. Hoppin and L. A. Norman. Jr.; and (2) reports of the California Division of Mines entitled "California Mineral Production."
' Before 1911 and in 1921 value of production of "Sand and gravel" included with "Crushed and broken stone."
during the 1950's: kunzite was mined at Pala; garnet at Ramona; and in 1958 tourmaline again was being mined at the famous Himalaya mine in the Mesa Grande dis- trict. But the real highlight of San Diego County's min- eral industry during the' postwar period was the growth in production of sand, gravel and stone, and the leading producers of these commodities: Caudell and Johnson; H. G. Fenton Material Company; Nelson and Sloan; Canyon Rock Company; Daley Corporation; H. W. Rohl Company; and others.
MINERAL PRODUCTION
The total value of the mineral production of San Diego County from 1870 to the end of 1959 is estimated to be about $125,000,000, of which slightly more than $75,- 000,000 was recorded from the end of World War II through 1959 (Fig. 3 and 4). In 1959 the total value of mineral output was about $14,489,600, to place San Diego 14th among the counties of California (California Di- vision of Mines, Mineral Information Service, October 1960, p. 5, 7).
The recorded amount and value of mineral commodi- ties produced annually in the county from 1880 to 1959 are shown herein on Table 1. Statistics shown for the
" Statistics do not include large output from the Stonewall Mine (see text).
0 Includes production for most of present-day Imperial and Riverside Counties.
7 Includes production of present-day Imperial County.
s Included with "Unapportioned and miscellaneous" so as not to reveal output of single
producer. 0 Source of output is probably Imperial County.
10 Includes value (if 800 tons produced from about 1892 to 1900.
11 statistics for commodity apparently not collected and compiled before this year.
12 Includes value of "Brick and tile" produced. Value of production included with "Pot-
tery clay." 1:1 Statistics for bentonite produced after 1940 are included with "Clay." "The production of brick in the county was recorded from 1898 to 1946. Since 1946
the production of common clay used in the manufacture of brick has been compiled
with "Clay." Statistics for brick production prior to 1917 include only brick, after
that date include both brick and tile. 35 Value of production of "Paving blocks" included with "Crushed and broken stone."
period from 1880 to 1894, which include only produc- tion of gold and silver, were compiled by the California State Mining Bureau from records and publications of the U.S. Mint and the U.S. Geological Survey. In 1894, the California State Mining Bureau (older name for the California Division of Mines and Geology) began to compile statistics for all commodities by canvass of all known mine operators, and, as the California Division of Mines, continued its compilation until 1946. Since 1946, the U.S. Bureau of. Mines has compiled all statewide production statistics. In addition, since 1944 statistics for San Diego County also have been compiled by the San Diego County Division of Natural Resources.
Statistics for the production of "mineral water" and "brick and hollow tile" were included with mineral production data compiled from the late 1890's to 1946, but as these are not true mineral commodities their production has not been compiled since 1946. Statistics for the production of "mineral water" collected before 1946 have been eliminated wherever possible from the present table; statistics for "brick and tile" have not been deleted, however, because they represent the only record during that period of the production of common
1963]
San Diego— Mineral Resources Table 1. Recorded Mineral Production of San Diego County— Continued
43
Pebbles for grind- ing (and filtering)28
Stone,
dimension3
Stone, crushed and broken1- 16
Sand and gravel '• 4
Unapportioned and miscellaneous1'28
Total yearly value
(Tons)
(Value)
(Cu. ft.)
(Value)
(Tons)
(Value)
(Tons)
(Value)
(Value)
(Description)
Year
73
1.000
B
s s
29,500
31.100 25,300 24,400
22,100
23,000 29.000 17,700 15,500
92,800
115.100 95,000 91,100
83,600
87.300 113.600 54,100 70.700
25
26 25 25 25
139,100
80,900 185,700 168,500
8
378,200
8
562,400
744.000
32397,800
01,347,900
81,502,300
"1,675,100 522,356,800
921,900
1,195,000 1,395,700 1,461,900
2,016.200
1,788.100 2.653.400 3,100,500 4,079.300 2,793,500
3,231,200
3,392,100
4,860,300
7,229,200
988,800
1,324.800 1,830,000 1,906,900
2,850,600
2,501,400 3,302,900 4,287,400 4,718,800 4,557,600
5,375,600
5,472,400
6.922,800
11.426,300
2L 22287,700
346.100 422.200 360,500
731,200
388,800 846,200 442,000 450,900 479,300
550,900
587,600
615,000
706.500
Brick and tile, limestone, magnesium chloride, mineral water,
1,740,800
1,882,400 2,594,100
2,544,600
3,689,100 3.381,100 4,289.300
6,036,300
5,456,800
7,322,400
7.562.300
9,212,900
14,489,600
76,600 89,400 69.200
1946
Magnesium chloride, pebbles for grinding, pyrophyllite, salt
Magnesium chloride, pebbles for grinding, pyrophyllite, salt.. Magnesium chloride, peat, pebbles for grinding, pyrophyllite,
M
1947 1948
1949
Limestone, magnesium chloride, peat, pyrophyllite, crushed
242,100
1950
Magnesium chloride, salt. __ . ._
Limestone, magnesium chloride, salt, crushed and broken stone.
Magnesium chloride, pyrophyllite, salt, quartz sand, silver
Gem minerals, gold, magnesium chloride, pyrophyllite, tung- sten concentrates, salt ... _ _ ... ..
Gem minerals, gold, magnesium chloride, salt, strontium min- erals, tungsten concentrates _ . . _. .-
Clay, gem minerals, gold, magnesium chloride, pyrophyllite, salt, silver, strontium minerals, tungsten concentrates
Clay, gem minerals, gold, magnesium chloride, pyrophyllite,
1951
1952
340,200 504,600 164.700
400,800
600.400
825.600
1,430,600
1953
1954
1955
1956
1957
1958
Clay, gem minerals, gold, magnesium chloride, pyrophyllite.
1959
Total (Recorded production, 1894-1959) $110,600,000
Estimated total mineral production (1870-1960) $125,000,000
6 "Crushed and broken stone" includes value of "Sand and gravel" produced before 1911
and in 1921, and value of production of rubble, riprap, paving blocks, urnamental stone, and pebbles for grinding (1915-18. 1921-28).
7 Value of paving blocks produced during the year is included with "Unapportioned and
Miscellaneous."
8 Includes tonnage and value of production of certain specialty sands: molding, blasting,
engine, and filter sand, and sand for asphalt finishing. 8 Known production apparently is not recorded.
0 No deposits of asbestos known in San Diego County; perhaps production is from River-
side County.
1 Includes some value of production of "Mineral Water." which was formerly considered
a mineral commodity. The production of mineral water has not been recorded as a mineral commodity since 1946. For production until 1943 see the report by Dol- bear (1944. pp. 92-95).
2 Includes value of production of "Brick and tile." formerly considered a mineral com-
modity (see footnote 14).
'Figures rounded to nearest "10," "50," or "100."
1 Production included with statistics for Imperial County.
' Statistics included with "Crushed and broken stone."
'Statistics for years 1925, 1927, 1928, and 1931-1943 are published by permission of
single producer. 'Statistics for years 1921-46 are published by permission of single producer. ' Statistics are published by permission of single producer. 'During 1917 and 1922-26 statistics for production of additional tonnages of clay were
combined with other commodities. ' Does not include value and tonnage of "Clay products, heavy clay (other than pottery
and refactories) " because U. S. Bureau of Census was not at liberty to publish
figures, production may represent ore milled in county but mined outside. 'Includes production of "Dimension stone." 1 Production of pebbles for grinding and filtering included with "Stone, crushed and
broken."
clay for manufacture of brick. Since 1946, statistics for all types of clay produced have been published together as "clay."
LAND OWNERSHIP AND ENTRY
The general pattern of ownership and administration of land in the county, as of 1955, is shown herein on PI. 11. Ownership for most individual mineral proper- ties, as of the period 1955 to 1960. is provided in the descriptions of mines and mineral deposits in the text and tabulated lists of the report. Up-to-date information on ownership data should be sought as follows: (1) patented property in general, San Diego County Asses- sor; (2) patented claims and claims for which patents have been applied, United States Bureau of Land iMan- agement, Riverside; (3) unpatented mining claims, San Diego County Recorder. The up-to-date status of various U.S. government lands should also be sought from the U.S. Bureau of Land Management, Riverside.
Mining law, as it pertains to locating claims, the use of water, safety regulations, and other points, is explained in a booklet entitled "Legal Guide for California Pros-
pectors and Miners" which is published and sold by the California Division of Mines and Geology.
Maps that are most useful to the prospector for loca- tion of deposits and delineation of claims are included in the series of topographic maps published by the United States Geological Survey, Washington 25, D.C. Maps of this series published at scales of 1:62,500 and 1:24,000 cover San Diego County, as shown on Plate 2 (see also Fig. 5). The location of one of three mineral monuments in the county is shown in Figure 6. Vertical aerial pho- tographic coverage of the county may be obtained from the United States Department of Agriculture, Commod- ity Stabilization Service, Salt Lake City, Utah. Other agencies, in addition to the California Division of Mines and Geology, which may have information of value to a prospector in the county are the San Diego County Division of Natural Resources, San Diego; California Di- vision of Industrial Safety, Los Angeles; California De- partment of Water Resources, Escondido office; United States Soil Conservation Service, Escondido office; and the United States Forest Service, Escondido and Des- canso stations, and the San Diego office. Information
44
California Division of Mines and Geology
[County Report 3
<k-
\
9>
9>
J
X
..J
Figure 5. Map showing first coverage of San Diego County by topographic maps of the United States Geological Survey. For modern coverage, see plate 2.
regarding county use permits, which are required for surface mining and petroleum exploration operations, may be obtained from the County Planning Commission, San Diego.
For this discussion, land is divided into three cate- gories: ( 1 ) land open to prospecting and location of mining claims; (2) land possibly open to prospecting by permit, but closed to location of mining claims; and (3) land closed to prospecting and location of mining claims.
LAND OPEN TO PROSPECTING AND LOCATION OF MINING CLAIMS
Land open to prospecting and location of mining claims consists of vacant, unappropriated public land (public domain) which is administered by the United States government. As of 1955, about 15 percent (409,- 397 acres) of the total land area in San Diego County consisted of unappropriated public domain. All of this land was in the mountainous areas of the county, espe- cially along the west edge of Anza-Borrego Desert State Park; along the Mexican border, between the west side of the San Ysidro Mountains and the Campo area; in the Cleveland National Forest; and in the Rincon area (see PI. 11). In 1957, however, parts of the public domain in the McCain Valley and Jacumba areas, and in the San
Ysidro Mountains were being considered for withdrawal into "wildlife management areas." Regulations of the United States and the State of California that apply to location of claims on the public domain are explained in the legal guide, previously described.
Most of the Cleveland National Forest is open to pros- pecting and location of mining claims, except private lands within the forest, campgrounds, picnic areas, for- estry station sites, fire lookout sites, summer home tracts, and lands which are operated privately by permit as or- ganization camps and recreation areas. Access to many parts of the forest is restricted, however, during the fire season and no part of the forest off paved roads should be entered during this season before contacting a ranger. Under the Multiple Use Act, the government retains the right to manage the surface resources, which remain pub- lic property. The claim holder may use timber from the mining claim for development of the claim, but it must be cut by use of proper forest management, as prescribed by the Forest Service. Before a claim holder may build an access road to his claim, he must obtain a permit from the Forest Service. Patents may be applied for claims in the national forest, as on the public domain outside.
1963]
San Diego— Mineral Resources
45
For information regarding prospecting in the Cleveland National Forest, the prospector should contact the office of Forest Service concerned with the part of the forest he is in:
(1) Trabuco District (Santa Margarita Mountains in San Diego County; and Riverside County)
Santa Ana
(2) Palomar District (Palomar Mountain region)
Escondido
(3) Descanso District (central and southeastern San Diego County)
Descanso
LAND POSSIBLY OPEN TO PROSPECTING BY PERMIT, BUT CLOSED TO LOCATION OF CLAIMS
Lands that are closed to location of mining claims, but possibly open to prospecting include Indian reservations, lands owned by the State of California, and privately owned lands.
Indian Reservations
Indian reservations comprise 110,036 acres of San Diego County, as shown on PI. 11. One who desires to prospect or to develop a mineral deposit on an Indian reservation must first obtain permission to do so from the tribe concerned, then make application to the United States Bureau of Indian Affairs. The person to contact in each tribe can be identified through the Area Field Rep- resentative, Riverside Area Field Office, United States Bureau of Indian Affairs, Riverside.
The following description of the procedure for making application to the Bureau of Indian Affairs for a pros- pecting permit on Indian lands was extracted from a letter received by the Division of Mines from the Sacra- mento office of the bureau in December 1957:
1. The authority from the tribe to grant a permit for pros- pecting must be in writing and contain the following information:
a. The name and mailing address of the person to whom the permit is to be issued.
b. A description of the tract of land to be prospected. This de- scription should be in accordance with the public survey, if possible, otherwise a description by known and readily discernible landmarks encompassing the area should be given. An estimate of the acreage involved should also be included.
c. The period of time for which the permit is desired. Pros- pecting permits are issued for periods of time varying from 30 days to one year from the date of the approval by the area director.
d. The type of prospecting permit desired. There are two types of permits that we are authorized to issue without an adver- tised sale, (1) a nonexclusive without option to lease and (2) a nonexclusive with option to lease 40 acres.
e. The amount of remuneration that the tribe will receive for granting the permit.
2. When the authorization is secured, the prospective permittee must submit it and the following additional documents to our Riverside area field representative:
a. If the prospective permittee is other than an individual (i.e., company, partnership, corporation), a copy of the articles of incorporation as approved by the state in which incorpo- rated (and if out-of-state, approval by the State of Califor- nia), and a copy of the minutes of the meeting in which the present corporate officers were elected.
31 T 9 S , R
32 2 E.. S B.M.
33
34
35 ^ 36
T IOS., R 6
2 E , S B.M 5
4 S44°36'l5"E 2756 32 (computed )
3 •£
r\ y
*^U. S. M.
^ /
2 M. 194
1
Figure 6. Map showing location of U.S. mineral monument in San Diego County, about 8Vi mi. west-northwest of Warner Springs on Aguanga Mountain. Description: M.M. No. 194 Sec. 3, T. 10 S., R. 2 E., S.B.M.S. 50° 19' 25" W. from V* corner common to sees. 35 & 36, T. 9 S., R. 2 E., S.B.M. 11,673.75 ft.
b. A remittance made payable to the Bureau of Indian Affairs for the amount specified in the petition. (If the prospecting permit is not issued, the remittance will be refunded.)
3. The field representative at Riverside will verify the signatures on the authorization and forward all of the documents to this office for the preparation of the prospecting permit.
4. The prospecting permit will be prepared and sent to you for signature and securing of a performance bond from an acceptable surety company, in an amount that will be specified within the permit. (The amount of bond is determined by this office and is dependent on the amount and type of land involved.) After signa- ture, the permit and bond must be submitted to this office for the approval of the area director.
A prospecting permit gives the permittee authority to prospect only, and to remove ore samples for the purpose of testing and assay. No mining can be done and ores cannot be removed for any other purposes. (Refer to Section 186.27a, Part 186, CFR-25, which is available from U.S. Bureau of Indian Affairs.)
Mining operations can be conducted on tribally owned trust land only with a valid lease prepared in accordance with Part 186, CFR-25. In general the requirements for a mining lease are as follows:
1. It must be proven that there are minerals in sufficient quan- tity to make the mine financially feasible. We are required to have the U.S. Geological Survey examine the mine site and sub- mit a full report on their findings including a recommendation concerning the feasibility of the proposed mine.
2. If a satisfactory deposit has been located, the lease is issued in the following manner:
a. By negotiation with the holder of a valid prospecting permit which covers the land to be leased and contains the option to lease 40 acres, or
b. If subparagraph (a) does not apply, by advertised sale.
3. The proposed lessee must be able to submit a plan for the proper development of the mine and show that he has the neces- sary assets to carry out the plan of development.
4. The proposed lessee must submit six copies of a plat of the • area to be leased, drawn to scale. If the land to be leased cannot be described by metes and bounds in accordance with the public survey, the proposed lessee at his own expense, must have the land surveyed. The surveyor's traverse computations must also be submitted.
In answer to your other questions concerning mining claims on lands set aside as Indian reservations, the following information is furnished:
1. When reservations are established, there is usually an excep- tion that states the land is subject to all valid claims and rights in existence.
2. If a claim is proved to be valid, it is under the jurisdiction of the Bureau of Land Management to determine if the claim can be patented.
46
California Division of Mines and Geology
[County Report 3
3. If a claim, which was valid at the time the reservation was established, is abandoned, it cannot be relocated or renewed since any action which affects the land after the establishment of the reservation must be in accordance with the applicable federal regulations.
State Lands
State lands in San Diego County include: (1) state- owned lands— land deeded to the State by the United States government for support of schools (generally Sections 16 and 36 within each township), and (2) Anza- Borrego Desert State Park. The methods for obtaining permission to prospect on these two types are described below.
State-owned Lands. Application for a permit to pros- pect on state-owned lands may be issued by the State Lands Commission, State Building, Los Angeles 12. Such permits are issued to qualified applicants only for land that is not known to contain valuable mineral deposits at the time of issuance of the permit. Lands that contain valuable mineral deposits are subject to lease by the State on a rental and royalty basis pursuant to competitive public bidding. Copies of the regulations that pertain to prospecting permits and mineral leases may be obtained from the State Lands Commission. In December 1957 only about 10 parcels of state-owned land in San Diego County were available for issuance of prospecting per- mits.
Anza-Borrego Desert State Park. Anza-Borrego Des- ert State Park is the only state park in California open to prospecting. A large part of the park was acquired by patent from the United States government which withheld the mineral rights and instituted a procedure by which valuable mineral deposits could be developed.
A prospector who wishes to prospect in Anza-Borrego Park should first register with a ranger in the park. The prospector must follow very carefully the State Admin- istrative Code that covers the rules and regulations of the park. When the prospector finds a deposit, he must apply to the United States Bureau of Land Management in Los Angeles for a mineral lease. This application must be in accord with the directions described in Circular 1673: "Code of Federal Regulations Title 43, Public Lands: Interior, Chapter I, Bureau of Land Management, Part 199, Mineral Leases in Lands Patented for Park and Other Public Purposes." After the lease is obtained, the pros- pector must apply for an easement for a right-of-way from the State Park Commission.
The procedure for application to the Bureau of Land A4anagement and the State Park Commission is extracted from a mimeographed statement distributed by the Divi- sion of Beaches and Parks:
Application to the U.S. Bureau of Land Management may, in accord with their procedure, be by letter. It must show the applicant's name and address, proof of citizenship, a statement of holdings by the applicant of leases under Sections 199.40 to 199.56 inclusive; pending applications therefore; interests, di- rectly or indirectly held in such leases, etc. A description of the land by which the legal subdivisions may be determined, must be included. A statement regarding the nature and extent of the proposed use, type and kind of minerals, the estimated duration
of exploratory operations, the extent of operations, etc., must be given in the application.
Leases may be issued for a period of five years. Applications must be accompanied by a minimum fee of $10 for each applica- tion embracing not more than 800 acres. If leases are entered into, each lessee will be required to furnish to the U.S. Government a bond in such sum as may be determined adequate, in no case less than $1,000, to insure compliance with the terms of the lease, and for the protection of the surface owner, the State of California.
Following the issuance of a mining lease, and prior to the commencement of any work, the lessee must apply to the State of California, Department of Natural Resources, Division of Beaches and Parks (Southern California office is District 6, P.O. Box 1328, San Clemente, California) for a right-of-way for an access road to the mining operations, in compliance with Section 5003.5 of the Public Resources Code, State of California. All applications must be submitted on Form BP-26. Eight (8) copies should be submitted to the District 6 Office in San Clemente, California; and must be accompanied by eight (8) copies of a map resulting from a survey by instrument of the road, etc., as noted and called for in the instructions for filing the application, Form BP-26. These instructions will be sent with the application forms upon request.
The State Park Commission will require a bond in connection with the granting of any easement for access roads, and this will be in an amount of not less than $1,000. This is for the purpose of guaranteeing compliance with the terms and conditions of the Right-of-Way Agreement, and will be in addition to any bond required by the Federal Government in connection with the mining lease.
Additional information may be obtained from Park Supervisor, Anza-Borrego Desert State Park, Borrego Springs, California; and District Superintendent, District 6, Division of Beaches and Parks, P.O. Box 1328, San Clemente, California.
Privately Owned Land
A prospector who wishes to prospect on private land may contact the owner through local inquiry or from information obtained at the county assessor's office. Pri- vate land composes most of the western part of the county.
LAND CLOSED TO PROSPECTING AND MINING
All military reservations, and state, county, and city parks are closed to prospecting and mining (except Anza-Borrego Desert State Park, which see). Also closed are rights-of-way for public utilities, highways, and reservoir sites.
CITY AND COUNTY ZONING
Zoning is one of the major problems that confronts any company which plans to begin, or move, a mining operation. Zoning ordinances in regard to such operations have been established by most incorporated communities in the county, and the unincorporated areas are covered by a county ordinance. Although the ordinances vary in detail, all provide that applications for the establish- ment of rock products operations are subject to a public hearing and consideration by a planning commission, city council or other designated authority. The ordinances also provide that rock product operations be specific distances from residential districts, schools, churches and certain types of businesses.
1963
San Diego— Mineral Resources
47
WATER FOR MINING OPERATIONS
Water has become very dear in San Diego County, as population and industry have grown and drought years have continued. There are three principal sources of water in the county: wells; storage reservoirs which hold runoff from precipitation; and the Colorado River aque- duct. The principal use of water by the mining industry of San Diego County in 1959 was for washing sand, gravel and stone products. Water for this and allied pur- poses is obtained chiefly from company-owned or leased wells in the major stream valleys in the San Diego region. In 1959, the H. W. Rohl Company, Oceanside, was op- erating a well which pumped brackish water, suitable only for industrial use. The Crystal Silica Company, also in Oceanside, was rationed water by the Citv of Ocean- side and therefore was forced to reclaim used water by recycling through a series of settling ponds. Additional water for mining in areas north of San Diego possibly may be obtained from wells drilled in sandstone of Eo- cene age which forms a narrow belt along the coast from Del Mar northward to the Orange County line (see PI. 1). Water from these rocks is reported to be too brackish for agricultural use and only barely suitable for domestic use (Ellis and Lee, 1919, p. 253-254; Babcock, 1958).
In the interior of the county, wells drilled in bedrock composed of granitic or metamorphic rocks may be the only source of water for mining operations, if sources such as springs, streams, valley fill and privately or pub- licly owned lines are not available or suitable. In sedi- mentary rocks, such as those along the coast, faults may create impermeable, waterless barriers, but in granitic and metamorphic rocks, fault zones commonly comprise permeable, water-bearing zones which should be con- sidered as possible drilling targets (Merriam, 1951). In addition, dikes, contacts, minor planar features (such as joints, schistosity and rock cleavage), and intersections of any of these features, also are possible targets. The water-bearing potential of these features can be evaluated by geologists, through detailed field studies and by use of detailed geologic maps and/or relatively large scale vertical aerial photographs. Vertical aerial photographs of San Diego County may be purchased from the Com- modity Stabilization Service, United States Department of Agriculture, Salt Lake City, Utah. As yield from wells driven in bedrock is generally much lower than from wells driven in sedimentary rocks, radials driven out- ward from the bottom of drill holes are used to increase flow.
The principal references that deal with groundwater in San Diego County are: Ellis and Lee (1919); Merriam (1951); Babcock (1958); and publications of the Cali- fornia Department of Water Resources (before 1956, Division of Water Resources). These and other refer- ences that deal with ground water are listed in the bibliography on "Water Resources, Soils, and Engineer- ing Geology" at the back of the text. For local informa- tion concerning water in San Diego, contact the Cali-
fornia Department of Water Resources office in Escon- dido.
PREVIOUS DESCRIPTIONS OF MINERAL DEPOSITS
Descriptions of mineral deposits and mining activities in San Diego County have been provided by the Califor- nia Division of Mines and Geology (which before 1928 was named the California Mining Bureau) since 1886. Early, rather short descriptions and accounts were pro- vided in the annual reports of the State Mineralogist by Hanks (1886), Goodyear (1888, 1890), Preston (1890), Storms (1893), and Crawford (1894, 1896). The annual reports were not published from 1896 to 1916, but in 1902 a tabulated list of the mines in the county prepared by Hubon was published as a Register of Mines. In 1914, a comprehensive report entitled "Geology and Mineral Resources of San Diego and Imperial Counties" by F. J. H. Aierrill was published separately by the bureau, then reprinted in its 14th report, which was published in 1916. Reports on mining in the county were prepared between 1921 and 1943 by W. B. Tucker, of the Mining Bureau's Los Angeles office, which was created in 1920. The most detailed and comprehensive of these reports was pub- lished in 1925. R. J. Sampson assisted Tucker, and pre- pared reports from 1930 and 1943.
The last general report on the county was written by Tucker, assisted by C. H. Reed of the San Diego Mining Bureau, and was published in 1939. Since 1943 the San Diego County Division of Natural Resources has pre- pared yearly a short summary of the mining activity in the county.
Descriptive reports of particuter deposits, districts, or commodities have been written by Hudson (1922), Don- nelly (1934), Creasey (1946), Hoppin and Norman (1950), Jahns and Lance (1950), Durrell (1953), Jahns and Wright (1951), Hanley (1951), Cleveland (1960), and others. Short descriptions or notations of San Diego County deposits are given in California Division of Mines Bulletin 176, "Mineral Commodities of California," which was published in 1957. Additional references concerning mineral deposits and mining activity are provided in the subject bibliographies entitled "Mineral Resources and Mining" and "Pegmatites" at the back of the text.
MINERAL COMMODITIES AND DESCRIPTIONS OF MINERAL DEPOSITS
The principal mineral commodities of commerce, and selected mineral-use groups, as they apply to the mineral industry of San Diego County, are discussed below in alphabetical order. In these discussions data is provided on the character and distribution of deposits, the history of mining operations, the methods of mining and mill- ing, products and value of production, and other material. Descriptions of the deposits, and of present and former mining operations, follow the pertinent commodity dis- cussions, either within the text, or in tabulated lists. Also in the tabulated lists are names and descriptions of claims, groups of claims, prospects and mills. Synonyms arc given in the lists for all types of entries, and are cross indexed.
48
California Division of Mines and Geology
[County Report 3
Those descriptions, within the tabulated lists, that arc initialed "R.M.S." were prepared by Richard M. Stewart.
The following mineral commodities are not known to occur in the county: barite, cadmium, chromium, mer- cury, platinum, sulfur, talc and soapstone, and titanium.
For readers unfamiliar with the subdivision of the township and range system, as used herein to describe location and property holdings, diagrams illustrating its use are given in the "Legal Guide for California Prospec- tors and Miners" published by the Division of Mines and Geology. Ownership data provided in the report are changeable and should be confirmed with the offices of the San Diego County Assessor (patented property) or San Diego County Recorder (unpatented property). Full descriptions of all references cited within the text or tabulated sections are given in the "Collective Bibliogra- phy" at the back of the text.
ABRASIVES
The beaches between Oceanside and San Diego were the principal sources of pebbles for grinding in California from 1915 to 1949 (Troxel, 1957, p. 27). During the early years of production an important locality was the beach near Bird Rock, south of La Jolla (Bradley, 1917, p. 80). Later, the principal localities were the beaches between Carlsbad and Encinitas, and especially at Ponto. John Momand, of Carlsbad, recovered pebbles for grind- ing and filtering from Ponto Beach and other localities from 1929, or before, to 1949. His output of the later years was purchased mainly by the Crystal Silica Com- pany for use in filtering systems (see Ponto Beach under "Sand and Gravel, and Crushed and Broken Stone").
The pebbles marketed for grinding ranged in diameter from three to six inches, and were sold for $65 per short ton (Troxel, 1957, p. 27). They were composed mainly of silicified metamorphic and igneous rock types. Porce- lain balls generally now have replaced pebbles for grind- ing, but for businesses where they have not, pebbles must
be purchased from midwest United States or foreign sources.
Garnet, which is used as the abrasive for some types of sandpaper, is found in very small proportions in peg- matite dikes (see "Gem Minerals") and in tactite bodies (see "Tungsten"). At the present time, however, none of the deposits in the county are potential sources of garnet for use as an abrasive.
An undeveloped deposit of volcanic ash (pumicite) occurs north of Borrego Springs (see Pompai group under "Volcanic Ash" in tabulated list). Volcanic ash is used as a mild abrasive.
AGRICULTURAL MINERALS AND SOIL AMENDMENTS *
The Circle Group Deposit near Jacumba might be considered as a possible source of vermiculite for use as an agricultural mineral (see description in section on "Vermiculite"). Expanded vermiculite improves the tex- ture of heavy clay soils (Rollins, 1951, p. 98). Expanded shale also has been considered for the latter use (see "Ex- pansible Shale"). Bentonite from the Otay Deposits (see description under "Clay"), near Otay and San Ysidro, might be suitable as an additive to coarse-grained soils, to improve their water-holding ability.
Other minerals that occur in San Diego County which may be of possible value as agricultural minerals are gypsum (see under "Gypsum"), which occurs along the east edge of the county; limestone (see section on "Lime- stone-dolomite"), which may be added to acid soils; and phosphate-bearing nodules in the Linda Vista terrace de- posits, which occur between Mission and San Dieguito Valleys (see under "Phosphates"). The latter deposits may be too low grade, however, even to be considered as possible economic sources.
Peat from the San Luis Rey Deposit has been used as a soil amendment (see under "Peat").
* As defined in the fertilizing materials article of the Agricultural Code of California. (See Rollins, 1951, p. 80.)
Abr olives
Map
No.
Nome of claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
l
Bird Rock deposit
On the sea coast, about 2 miles south of down- town La Jolla.
Beach pebbles.
An early source of pebbles for grind- ing. See text. (Bradley 17:80).
Golden Stump Ext. #1
"Laguna Mountains".
Undetermined (1958) J. N. Sexton (1939)
Listed as a "garnet" claim by Tucker and Reed (1939) . No additional published information. See also Golden Stump in tabulated list under "Gold." (Tucker and Reed 39:54).
Ponto Beach (Abizaid)
South of Ocean- side.
Formerly a source of pebbles for
grinding and for filtering. See tabu- lated list under "Sand and gravel, and crushed and broken stone." (Troxel 57:27) .
Unnamed
Fish Creek area, about 10 miles south of Ocotil- lo Wells , in Anza-Borrego Desert State Park.
Merrill (1914) reported that Bert Sim- mons of El Cajon, and Homer Bailey of San Diego had located claims on a deposit of massive garnet in sec. 25, T13S, R8E, SBM. Occurrence has not been substantiated. (Merrill 14:705).
1963
San Dm <;<>— \Ii\ik\i Resources
49
ALUMINUM MINERALS
The most alumina-rich rocks in San Diego County arc ( 1 ) beds of clay in the western and eastern parts of the county which probably contain less than 20 percent alumina (aluminum oxide); (2) the granitic rocks of in- termediate composition in the middle of the count)-, which probably contain about 15 percent alumina; and ( 3 ) feldspar-bearing beach sands, and sandstone deposits of Eocene age. These rocks, how ever, all contain much smaller proportions of alumina than alumina-rich and high-alumina clays which have been considered as pos- sible sources of aluminum ore in other parts of the United States.
ANTIMONY
Commercial deposits containing antimony have not been found in San Diego County. The only reported oc- currence of this element in the county is in the Mesa Grande district where stibiotantalite (oxide of antimony and tantalum) and stibiocolumbite (oxide of antimony and columbium) occur in extremely small proportions in gem-bearing pegmatites (R. H. Jahns, California Institute of Technology, personal communication, 1957).
ARSENIC *
Arsenopyrite, the sulfarsenide of iron, is a common accessory mineral in the gold-bearing quartz veins in most of the gold districts of San Diego County. It is abun- dant locally in such veins. Large concentrations of arseno- pyrite were found in, and near, the quartz bodies of the Gold Cross No. 1 Deposit in the Julian district (Don- nelly, 1934, p. 360-361); and the ore from the Willhite Mine, in the Laguna Mountains, was reported to contain abundant arsenopyrite (Tucker and Reed, 1939, p. 12).
Only the Black Mountain Deposit, which contains ar- senopyrite and minor proportions of gold, has received attention as a possible source of arsenic. A treatment plant to recover both arsenic and gold was erected near the deposit, and in 1924 a small amount of arsenical concen- trates was shipped.
* By R. M. Stewart.
Black Mountain Group
Location: Sec. 5, T. 14 S., R. 2 VV., S.B.M.; on the
north slope of Black Mountain, about 6% miles north of Miramar. Ownership: Oliver Wylie Estate, c/o Mrs. Margaret VV. Horner, 200X Fremont Ave., South Pasa- dena (1955).
Efforts to recover arsenic and gold from this deposit were confined mostly to the 1920's. According to records made available by the owner, the Mace Company, Den- ver, Colorado conducted smelting tests on samples of the arsenical ore to produce a gold-bearing matte and recover arsenic trioxide as a fume. No plant for such a process was developed. A small concentrating plant was erected earlv in 1924 even though no ore reserves had been de- veloped. This also was impractical because of an insuffi- cient water supply and was shut down and dismantled in Julv of that year. Subsequently, but before 1930, a Gates rotary roaster (estimated from remaining brick- work to have been 15 feet long and 5 feet in diameter) was installed. A reinforced concrete stack, 5 by 6 feet in cross section and 180 feet long, was constructed directly upon the hillside and connected to the roaster by a metal pipe. A small crushing plant provided crushed material for the roaster. Presumably arsenic was to be recovered from condensed fumes in the stack. Three cyanide leaching tanks to treat the roasted ore for gold recovery also were installed but never used. Only a ton or two of ore was ever roasted. The only recorded ship- ment from the property consisted of 700 pounds of ma- terial containing 31.4 percent arsenic, plus a small amount of gold and silver, which was sent to a chemical plant at Martinez, California in 1924. Several unsuccessful efforts to develop the deposit have been made since 1930, but none recently. The concrete stack, crushing plant struc- ture and brickwork for the roaster were all that remained of the plant in mid-1955.
Arsenopyrite is distributed rather sparsely as small masses as large as 3 cm. long and 0.5 cm. thick along fractures and seams in fine-grained quartzite which is a member of the Black Mountain volcanic rocks of prob- able Jurassic age (Hanna, 1926a, p. 199-201, map).
Map No
Nome of claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
Slack Mt. deposit
Cedar Creek mine
Gold Cross No. 1 claim
Metal Mt. mine
Willhite group
North of Miramar.
San Ysidro Mts.
Julian district.
Northwest of Live Oak Springs.
Laguna Mts.
Arsenopyrite with galena and other minerals in quartz veins.
Large concentrations of arsenopyriti associated with gold in quartz vein.
Arsenopyrite with galena and tung- sten minerals in quartz veins.
Arsenopyrite in gold-bearing quartz vein.
See text. (Tucker 25:329; Tucker and Reed 39:12, pl.l) .
Developed for lead minerals. See tab- ulated list under "Lead". (F.H.W.)
Ore not mined as a source of arsenic. See tabulated list under "Gold". (Donnelly 34:360-361).
Mined for tungsten. See text under "Tungsten." (F.H.W.)
Ore not mined as a source of arsenic. See tabulated list under "Gold". (Tucker 25:329; Tucker and Reed 39:121
50
California Division of Mines and Geology
[County Report 3
Lenses of arsenopyrite have been reported, but no dimen- sions for them have been given (Tucker, 1925, p. 329). Pyrite and chalcopyrite are present in minor proportions within the arsenopyrite concentrations. The sulphides are auriferous.
The arsenopyrite concentrations are distributed discon- tinuously for a distance of at least 200 feet. The deposit has been explored inextensively by adits, shafts and shal- low pits and trenches. Two adits were driven about 30 feet apart on opposite sides of a small canyon. The long- est extends S. 10° E. for 25 feet, then S." 28° E. for 50 feet. The other, to the north, extends N. 25° E. for about 30 feet. Two shafts now caved but reported to be 40 feet deep each (Tucker, 1925, p. 329), were sunk at the portal of each of the adits described above. There is no record of ore encountered in the shafts, and arsenopyrite- bearing material was found only in the first 25 feet of the longest adit (Harley Sill, 1930, private report). A shallow pit, 100 feet higher and 200 feet south of the main adit, exposed a zone containing arsenopyrite. A sample from that pit assayed 7.48 percent arsenic and 0.34 ounce of gold per ton (Harley Sill, op. cit.).
ASBESTOS
Asbestos occurs at the Circle Group Deposit, near Jacumba, which is described herein under "Vermiculite." It has been reported by Goodyear (1890, p. 148) to occur at a locality about three miles northeast of Warner Springs, but this was not verified by the present writer.
A production of 50 tons reported from the county in 1894 was probably from Riverside County (see Table 1).
BERYLLIUM
The mineral beryl (a silicate of beryllium and alumi- num) has been found in many of the gem mineral-bearing pegmatite deposits of San Diego County. The mineral has been mined from these deposits for gems and speci- mens, but none has been mined for beryllium. The known beryl deposits of the county, and the rest of California, average less than 1 percent beryllium oxide (BeO) and therefore never have constituted ore (Wright, 1957a, p. 75). Additional beryllium minerals that occur in the gem mineral deposits, but only rarely, are bertrandite, helvite, and phenakite.
The most significant beryllium deposits known in the county probably are the beryl-bearing pegmatite dikes of the Tule Mountain area, which is northwest of Ja- cumba. Beryl has been known to occur at one locality in this area since the early 1900's, and early in 1961 the mineral was discovered in several adjacent dikes as large, very pale green crystals (see description of Ruby group). The Jacumba region as a whole, and especially the Tule Mountain area, merit additional prospecting for beryllium minerals.
The only attempt, known to the writer, to develop a commercial beryllium deposit in San Diego County was in 1937 when the Beryllium Alloys Company, Vista, at- tempted to develop a reported beryl-bearing pegmatite
Be
r y 1 1 i u m
Map
Name of claim ,
Location
Owner
Geology
Remarks and references
No
mine, or group
(Name, address)
Crystal Gem mine
Nor t h- n or thwe s t of Jacumba.
See Ruby group herein and Crystal Gem mine in the tabulated list under "Gem minerals". (Kunz 05:152; Merrill 14: 693, 703).
Freeman
Northeast of Vista.
•
Map locality name used by Tucker and Reed (1939, pl.l) for a property des- cribed in their text as the Mountain Bell mine. Actually, "Freeman" was one of the owners of the Vista Chief property, to the north, in Moosa Can- yon ; Mountain Belle was one of the claims that composed the Vista Chief property (which is described in the tabulated list under "Gem minerals"). The "Mountain Bell" of Tucker and Reed (1939) probably is actually the Hogerman property, which see . (Tucker and Reed 39:13, pl.l).
3a
Hogerman property
Sees. 8 and 9,
Mrs. Vera Strand,
Reported as a discovery of beryl in
In 1937, Beryllium Alloys Company, San
(Mountain Bell
TT1S, R3W, SBM;
(address undeter-
a northwest-trending pegmatite
Francisco (W. E. Schoppe , president)
mine)
about 3 miles
mined) , La Mesa
dike. Occurrence not substan-
began to develop a deposit that
northeast of
(1957)
tiated by the present writer.
supposedly contained beryllium ore.
Vista, on the
The venture was short-lived and a
west slope of
failure, however. The site was a
the San Marcos
160-acre tract owned by the late
Mts.
Edward Hogerman of Vista. Workings developed by the company reportedly consisted of a 60-ft. cut and a 40-ft. adit. In 1957, the present investi- gator could only find a few shallow cuts in the NE^ sec. 8 and the NW^a sec. 9. (Tucker and Reed 39:13).
Mountain Bell
See Hogerman property. (Tucker and
mine
Reed 39:13) .
3b
Ruby group
N or t h- n or t hwe s t of Jacumba.
See text. (Kunz 05:152).
1963
San Diego— Mineral Resources
51
deposit on the Hogerman (Mountain Belle) property, northeast of Vista. This venture faded, however, and no ore was mined (see description in the tabulated list).
Ruby Group
Location: Mainly in the SE. 54 Sec. 2 and the NE. !4 Sec. 11, T. 17 S., R. 7 E., S.B.M.; about seven miles north-northwest of Jacumba, north of Tule Mountain, in the Sacotone Spring area. Ownership: The group com- prises three unpatented, north-northwest trending, con- tiguous claims which are owned by Don Weaver of Jacumba. Mr. Guida, also of Jacumba, owns a single claim at the south-southeast end of the group, in Sees. 11 and 12 (1961).
Beryl has been known to occur in the Sacotone Spring area since at least as early as 1904. In that year "Collier and Smith" were reported by Kunz (1905, p. 152) to have mined "10 pounds of fine essonite garnet and per- haps three or four pounds of beryl" from the Crystal Gem mine which he reported to be about Sl/2 miles northwest of Jacumba (see under "Gem Minerals"). Early in 1961, large crystals of beryl were discovered by Weaver in an area about one-third mile east of the deposit surmised by the present writer to be the site of the Crystal Gem mine. By mid- 1961 Weaver had opened several shallow cuts and pits in the deposits.
The deposits covered by the Ruby group consist of several beryl-bearing granite pegmatite dikes which are enclosed in a diorite-like metamorphic rock. The dikes strike north-northwestward and dip gently to moderately west-southwest into the upper part of a steep northeast- facing mountain slope. The dikes range in length from several hundreds to perhaps several thousands of feet; and they range in thickness from less than 5 to as much as 15 feet or possibly more. Beryl occurs with quartz and feldspar in cores of the dikes as nearly colorless to pale-green crystals which -range in length from less than one inch to at least two feet. Small crystals generally are pale green and glassy; large crystals tend to be irregular in shape, to be very pale in color, and to resemble feld- spar. Two large, pale beryl crystals that were analyzed (Smith-Emery Company, Los Angeles, 1961) contained 12.36 and 12.17 percent BeO.
One of the principal prospects in the group, in the NW. 54 NE. 54 Sec. 2, was examined in detail. This pros- pect develops part of a dike which is about 10 feet
thick and consists of a lower zone of line rock, an inter- mediate zone of fine-grained schorl-muscovite-quartz- perthite pegmatite, a core of coarse-grained beryl-quartz- perthite pegmatite, and an upper zone similar to the inter- mediate zone. The beryl-bearing part of the core extends laterally along the face of the dike for about 10 feet, pinching outward from a maximum thickness of about three feet in the middle. Additional minerals in the core are heterosite (purpurite?), pale green muscovite, and albite variety cleavelandite.
BISMUTH
Commercial deposits of bismuth have not been found in San Diego County. Extremely minor proportions of bismuth-bearing minerals occur in the gem-bearing peg- matites at Pala (Jahns and Wright, 1951, p. 38; Kunz, 1903a, p. 398-399), at Mesa Grande (R. H. Jahns, Cali- fornia Institute of Technology, personal communication, 1958), and at Rincon (Rogers, 1910, p. 208). These minerals include native bismuth, bismite (bismuth oxide), bismuthinite (bismuth sulfide), bismutite (bismuth oxy- carbonate), and others.
BORON
Deposits that contain boron in commercial proportions have not been found in San Diego County. The only boron-bearing minerals known to occur in the county are tourmaline (a complex boro-silicate), axinite (calcium, aluminum boro-silicate), dumortierite (a hydrous alu- minum boro-silicate), and hambergite (a beryllium bor- ate). Tourmaline is found in minor proportions in pegmatite dikes in many parts of the county, but mainly in the Pala, Mesa Grande, Ramona, Rincon, Chihuahua Valley, and Jacumba areas (see "Gem Minerals"). Axinite occurs at the Vista Chief Deposit, near Bonsall, which is described herein in the tabulated list under "Gem Minerals." Dumortierite occurs at the Dehesa deposit described herein under "Kyanite and Related Minerals." Hambergite is a very rare mineral which has been found at the Little Three Gem Aline near Ramona.
Three dry lakes in the eastern part of the county have been listed as containing "borates in varying quantities" (Bailey, 1902, p. 69)*. These are Clark, Bensons and Halfhill Lakes. However, the occurrences have not been verified bv the writer.
Map No.
Name of claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks arid references
4 5
Unnamed Unnamed
T11S, R8E, SBM; Benson Dry Lake, in northeastern San Diego County.
T9S, R6 and 7E , SBM; Clark Lake, in northeastern San Diego
County.
Reported in a list of unnamed dry lakes that "contain borates in varying quantities". An unsubstantiated occurrence. (Bailey 02:69) .
Reported in a list of unnamed dry lakes that "contain borates in varying quantities". An unsubstantiated occurrence. (Bailey 02:69).
52
California Division of Mines and Geology
Bromine
[County Report 3
Map No.
Name of claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
California Chem- ical Corpor- ation
Westvaco Chlorine Products Corp. (California Chemical Corp . )
Chula Vista.
See Westvaco Chlorine Products Corp.
(Ver Planck 57a:95; 58:115).
California Chemical Corp. constructed a Kubierschky tower at Chula Vista in 1926 and in it produced bromine compounds from salt works bittern until 1937. During that year the operation was taken over and contin- ued by Westvaco Chlorine Products Corp. (now Mineral Products Div. , Food Mach. & Chem. Corp.) until 1945. The company produced ethylene di- bromide and attempted to market liquid bromine. Mineral Products. Div. now produces only magnesium chloride. (Ver Planck 57a:95; 58:115).
BROMINE
Bromine was produced first in California in 1926 at Chula Vista, by the California Chemical Corporation (Ver Planck, 1957a, p. 95). This firm produced both magnesium and bromine from sea water bittern from 1926 to 1937, when it sold its operations at Chula Vista and Newark, California to Westvaco Chlorine Products Corporation. Westvaco continued to produce bromine at Chula Vista until 1945, but now, as Mineral Products Division, Food Machinery and Chemical Corporation, produces only magnesium chloride. The bromine was produced in a Kubierschky tower.
CALCITE (OPTICAL GRADE)
Calcite (calcium carbonate) is one of the most com- mon minerals in the earth's crust. In San Diego County it occurs as the principal constituent of limestone deposits at Dos Cabezas, and near Ranchita, Jacumba, Pine Val- ley, and Jamul. However, deposits that contain large clear crystals (Iceland spar) of optical or suboptical grade are very rare, and only two such deposits have been mined in California (Wright, 1957b, p. 99). One of these deposits is the Hilton, in the northeastern part of San Diego County, which was operated during World War II for suboptical grade material used in gun sights. Since that time, optical calcite has been replaced partly by polaroid in the manufacture of optical objects (Wright, 1957b, p. 99).
Co I C i t 6
Hilton Deposit *
Location: S.'/z Sec. 14, and S.y2 Sec. 15, T. 10 S., R. 8 E., S.B.M.; low on the east side of the Santa Rosa Moun- tains, about eight miles due west of Truckhaven, which is in Imperial County. The deposit can be reached by a fair but steep dirt road from the Truckhaven-Borrego Valley trail. The turnoff for the mine is about eight roadmiles west of Truckhaven. Ownership: Undeter- mined (1957). C. Jack Frost, Banning, and Robert R. Dye, Indio, owned five claims in 1947.
The Hilton deposit was discovered in 1936, and worked sporadically until 1942 by John Hilton and a Mr. Heather, who mined small quantities of unusual, thin, tabular calcite crystals which were sold as optical ma- terial. In 1942, the property was purchased by Calcite Operators, Incorporated, Thermal, which was managed by Arnold Hoffman. Calcite Operators worked the de- posit from October 1942 to October 1943. During this period the corporation employed as many as 30 men and held about 25 claims. The operation was resumed for a short time, on a small scale, in 1944 by C. Jack Frost and Robert R. Dye, former employees of Calcite Operators. The deposit has been idle since 1944.
About 6,800 pounds of sub-optical grade calcite was accepted by Polaroid Corporation of Cambridge, Massa- chusetts, from material mined and shipped from the de- posit during 1942-1944 (Durrell, 1944, p. 23). The calcite accepted was used in the manufacture of ring gunsights.
* The following description was taken mainly from an unpublished U.S. .Geological Survey report written in 1944 by Cordell Durrell. (optical )
Map No.
Name of claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
6
Hilton deposit
Northeastern part of county.
Unique optical calcite occurrence. See text. (Bowles 21:1-6; Bramlette and Eakin 43:1-4; Durrell 44:1-28; Ricker 43; Wright 50:136-138; 57b: 99-100) .
1963
San Diego— Mineral Resources
53
\ /
DISTRIBUTION OF MOST
OF THE WORKINGS IN THE
CENTRAL, HEATHER AND
DEFIANCE AREAS OF
THE HILTON CALCITE
DEPOSIT, NORTHEASTERN
SAN DIEGO COUNTY,
CALIFORNIA
EXPLANATION
Open cut; depth not shown
Figure 7.
Indicated reserves in the deposit were estimated by Dur- rell to be about 3,000 tons of useable calcite, to a depth of 48 feet.
The suboptical grade calcite occurs with common cal- cite and gypsum as veins which filled joints in the Canebrake conglomerate of Mio-Pliocene age (Dibblee, 1954, PI. 2). This formation underlies much of the bad- land which extends eastward from the Santa Rosa Moun- tains. In the area of the Hilton deposit the rocks are mainly thick-bedded conglomeratic sandstone which strikes northeastward and dips generally from 15° to 20° southwest (Photo 24). The joints that contain calcite strike N. 25° -45° W., and range in dip from 65° south- west to nearly vertical. They have a maximum length of
about 300 feet. Most of the suboptical grade calcite occurs in cavities (or "pockets") at intersections of joints, with elongation of the cavities generally extend- ing down the lines of intersection of the joints. The pockets are quite variable in size; one of the largest mined, as described by Durrell (1944, p. 11), was 22 feet long, 14 feet deep, and slightly more than two feet in maximum width. The useable calcite occurs mostly as basal plates which are as much as 18 inches in diameter and less than one-half inch in thickness. Growth lines and cleavages, either developed, or incipient, are common defects.
Four areas of calcite mineralization were designated and described by Durrell (1944) as follows: (1) the Central area, in the center of the S.'/2 Sec. 14, which has
54
California Division of Mines and Geology
[County Report 3
Photo 24. View southwest toward Hilton optical calcite deposit. Rocks in foreground are conglomeratic sandstone of Canebrake con- glomerate, of Mio-Pliocene age. Workings, which consist of trenches, are shown in center and right middleground. Segment of road to deposit from Truckhaven is shown at extreme right. Part of Salton Sea is barely visible at extreme upper left.
yielded 75 percent of the calcite mined in the region, and contains slightly more than half of the workings; (2) the Heather area, which is northeast of the Central area, in the NW. % SE. % Sec. 14, and is the second most intensely worked area; (3) the Defiance area, which is west of the Central area, in the S. VI SW.% Sec. 14, and is largely undeveloped; and (4) the Victory area, which is about one mile east of the Central area, in the S. VI Sec. 15, and is also largely undeveloped. Veins in the latter area, however, are largely gypsiferous, and cavities have not formed.
The veins were developed by about 75 trenches which range in length from 10 to at least 100 feet, in width from about 4 to 5 feet, and in depth to 30 feet (Photo 24, Fig. 7). Nearly all of the trenches are parallel to the strikes of the veins.
CESIUM
Pollucite (a hydrous silicate of aluminum and cesium) is a rare constituent of the gem pegmatite deposits of the Pala and Mesa Grande districts (W. T. Schaller in Murdoch and Webb, 1956, p. 255). Commercial quan- tities of this mineral were sought unsuccessful! v in 1929 by the General Electric Company at the San Diego mine, Mesa Grande district. Cesium also occurs as a very minor constitutent of pink beryl crystals which have been found in the Pala and Mesa Grande districts, and at Aguanga Mountain. The element also may be a constituent of similar unanalyzed crystals which have been found in the Ramona and Rincon districts.
CLAY *
The principal clay deposits in San Diego County lie along the coastal plain from Oceanside south to the Mexican border. Some are predominately marine mud- stone; others are claystone of residual origin; and still others consist of bentonite. Large and potentially useful claystone deposits occur in the eastern part of the county. Small deposits formed by hydrothermal altera- tion or weathering of pegmatites are in areas underlain by crystalline rocks. All of these deposits, with the ex- ception of the bentonite deposits, yield clays that may be used in ceramics, mainly for making bricks, but also for sewer pipe and other heavy clay products. These clays are not pure minerals but are mixtures of clay minerals, silt, sand and organic matter and are called clay materials. The clay minerals present, those which bind the other constituents together when fired, are kaolinite and illite or commonly both. Bentonite is used chiefly as an adsorbent in industrial refining processes. This material is largely composed of the clay mineral mont- morillonite. The properties and uses of both ceramic and bentonitic clays in California are summarized in Table 2.
The recorded output of clay in San Diego County from 1912 to 1956 is 559,438 tons valued at $1,406,031 (Symons, 1935; unpublished records of the California Division of Mines— U.S. Bureau of Mines co-operative program). However, the actual production may have
* By George B. Cleveland.
[1963]
San Diego— Mineral Resources
Table 2. California Industrial Clays.*
55
Principal commercial types
Principal mineral or minerals
Significant characteristics
and
chemical composition
Significant
physical
characteristics
Fired color
Industrial applications
Ceramic Clays I. Fireclay
II. Kaolin (China clay)
III. Ball clay
IV. Miscellaneous clay.
Bentonitic Clays (General )
I. Swelling bentonite
Kaolinite group Kaolinite group
Kaolinite and montmorillonite
Kaolinite and illite_
Montmorillonite, beidellite, and hectorite
—
Principally silica (40-55%) and alumina (20-45%).
Free from iron and alkalies with total oxide impuri- ties less than 3%. Often high in organic material.
Highly refractory; generally plastic
Low plasticity
High plasticity
Low heat resistance. .
White to red
White. ...
White to light cream
Red
Fire brick, ladle brick, fire clay mortar, drain tile, face tile, pottery.
Whitewares, refractories, filler in paint, rubber, and paper.
Whitewares; generally mixed with other clays to increase strength, bonding, and plastic properties.
Heavy clay products, building brick, face brick, paving brick, drain tile, sewer pipe; source of silica and alumina in cement; rotary drilling mud.
Suspending agent, filtering, decolorizing, filling agent.
Well drilling muds, binder in foundry sands, pharmaceu- ticals; and beverage clarifi- cation.
Filtering, filler, insecticide carrier, decolorizer, catalyst.
Filtering; decolorizer for waxes, resins and petroleum oils; catalyst, insecticide carrier.
Filtering; decolorizer for waxes, resins and petroleum oils; catalyst.
Principally alumina and silica (high in ferric oxides and other fluxes).
Principally alumina, silica, magnesia and lime.
High in Na, low in Ca.
High in Ca, low in Na; good decolorizers
Swells, forms a gel or suspension; high plasticity; non- activatable.
II. Non-swelling bentonite
(Adsorbent clays) A. Naturally active
(fullers earth) B. Activatable
(activated)
* Modified from Table 6, California Division of Mines Bull. 176, p. 144.
been nearly twice this much. Total clay production fig- ures are unavailable for clay mined prior to 1912, clay used in cement, and clay used by the clay companies be- tween 1933 and 1942.
Residual clay deposits that were derived from shale and conglomerate, and probably were formed in Paleo- cene time, occur east of Carlsbad and Cardiff. These de- posits are overlain by the Delmar sand, which is the basal member of the Eocene La Jolla formation. The clay is exposed only in relatively small areas where erosion has removed the overlying rocks. The clay is probably a product of the intense period of weathering which formed the valuable, residual and sedimentary fire clays of the Silverado formation in the northern Santa Ana Mountains area in Riverside and Orange Counties. Where the clay has been observed in San Diego County, it rests in gradational contact on a greenish-gray shale probably of Cretaceous age. In the vicinity of Carlsbad the shale
is mined for use in ceramic mixes to increase the strength of the fired body.
The Rose Canyon shale member of the Eocene La Jolla formation has been a continuous source of common clay in the San Diego area for over 70 years. It is dis- tributed widely in the coastal plain between Mission and San Dieguito Valleys, where it is overlain locally by the Eocene Poway conglomerate and thin terrace deposits of Quaternary age. The clay is best exposed in Rose Can- yon, north of San Diego, and mining operations there have centered near Elvira and Ladrillo (now abandoned) stations of the Santa Fe Railroad (Photos 27, 28). The shale member comprises two clay zones, one buff and the other bluish-gray, which have a total maximum thickness of about 250 feet. The two zones appear to be similar in composition, but they exhibit different drying charac- teristics. The shale in Rose Canyon proper contains only small proportions of soluble salts, but farther east, at the
California Division of Mines and Geology
Photo 25. Field or scove kilns on the Union Brick Company property. Bricks are dried in the sun, in fan-ventilated sheds or in hot air dryers, then fired in these kilns for 6 days. The leaning smokestack, which is a familiar landmark in Rose Canyon, was built in the late 1880's as part of an earlier brick plant.
Photo 26. View east toward Standard Oil Company mine workings on the south side of Otay Valley. Many thousands of tons of bentonitic clay were mined from this deposit for use in refining petroleum. The clay is in the middle or late Pliocene San Diego formation. Face at left is about 100 feet high. San Ysidro Mountains are in background.
1963
San Diego— Mineral Resources
57
Linda Vista deposit, the same rock contains deleterious proportions of gypsum (CaS04.2H:>0). The high con- centration of soluble sulfate in this deposit, if not immo- bilized by treatment with barium and other compounds, will cause the finished clay ware to effloresce and there- fore have a whitewashed appearance (Photo 25).
One of the principal deposits of high-grade bentonitic clay in California occurs along the Otay Valley near the Mexican border (Cleveland, 1960). This deposit was mined for more than 35 years and much clay still remains. The high-grade material is exposed only in an area of about 1.3 square miles, but it may be much more widely distributed (Photo 26).
Potentially useful deposits of low-grade clay occur in the Imperial formation which is probably early Pliocene in age. These clays, which are in the eastern part of the county, have not been thoroughly prospected and little is known of their properties and distribution. The clay, however, occurs in layers, at least several tens of feet thick, which underlie an area of over 100 square miles. Even if the clays prove to possess useful properties the remoteness from centers of population would limit their development.
Clay deposits formed by hydrothermal alteration or by the weathering of pegmatite dikes exist in San Diego County but are too small to be economic sources of clay.
Adobe bricks have been made from local deposits of clay material in the Escondido area for the past several years. The market for adobe bricks is small and unstable, however, and annual production in recent years has amounted only to about 20,000 standard bricks (4"x 12" x 16").
Near Oceanside several thousand tons of clay material were recovered, and sold as a byproduct of the mining of silica sand. This material was used in heavy clay products.
Kelley Ranch Mine
Location: SE.K NW.'/4 Sec. 14, T. 12 S., R. 4 W., S.B.M. (projected); about five miles east-southeast of Carlsbad. Ownership: Unapportioned estate of Lovinia I. Kelley (Irwin J. Kelley, Graham M. Kelley, Herbert C. Kelley, Jr., Thalia Kelley Considine, Barbara Jean Hig- don, Charles David Kelley and others). Address: Graham M. Kelley, Room 1130, Bank of America Building, San Diego. The property comprises about 750 acres of pat- ented ranch land.
Prior to 1913 the Hieatt Brick and Tile Company of San Diego recognized the value of the ceramic clay on the Kelley Ranch and leased 30 acres in the NW.% Sec. 15, T. 12 S., R. 4 W., S.B.M. (projected) from the Kelley interests. A small amount of clay was mined for testing before the lease terminated. The Pacific Clay Products Company of Los Angeles first opened the Kelley Ranch Deposit on a commercial basis in 1935 and mined clay from it until 1938. Beginning in 1948 the deposit was mined by Palomar Potteries of Vista, which produced small amounts of clay until about 1956. In 1954 this com- pany conducted an exploratory program northwest of
the mine in the vicinity of Letterbox Canyon, near the junction of Sections 10, 11, 14, and 15. Although several test holes were drilled and clay was found, no attempt was made to mine the clay. In 1957, Pacific Clay. Prod- ucts Company extensively drilled an area of about 300 acres west of the present workings and near their own property (Pacific Clav Products Company Mine) in Sec. 15, T. 12 S., R. 4 W.,' S.B.M. (projected)' The total clay production from this property is unknown, but the size of the excavation suggests that only a few thousand tons were mined. The deposit was idle in early 1958.
The clay deposit on the Kelley Ranch consists of a single clay layer which grades downward into shale and conglomerate of Cretaceous(r) age and is overlain un- conformably by sandstone of the Delmar sand member of La Jolla formation of Eocene age. The clay under- lies the crest of a rolling hill and is distributed over an area of about one square mile. The Delmar sand has been eroded away near the crest of the hill where the clay is exposed; however, at lower elevations the sand is several tens of feet thick. The clay layer consists of pink, purple and white mottled claystone with reddish- brown blotches of iron oxide and abundant angular frag- ments of quartz. In the vicinity of the workings it ranges from 2 to 14 feet in thickness and is overlain by a thin sandstone bed and as much as 6 feet of soil (Fig. 8).
The clay has been developed by a shallow pit which is triangular in plan, and is about 125 feet long in a north- south direction and 100 feet long in an east- west direc- tion.
The clay probably was formed on an irregular surface as a residual product of intense tropical weathering of the Cretaceous(P) shale during Paleocene(?) time. The area underlain by the clay is a nearly flat upland surface that is apparently the remnant of a Pleistocene(P) marine
gravelly soil claystone
G B Cleveland
FEET Approximate Scali
Figure 8. Geologic sketch map, Kelley Ranch mine.
58
California Division of Mines and Geology
[County Report 3
Foult
Hor izonta I bedding
Attitude of bedding
lond^lide/
TRoseV5^/ Rose
ConyonVJ Conyon
s hale"*^^ yz6 shale
G 6 Cleveland
FEET Approximate Scole
Figure 9. Geologic sketch map, Linda Vista mine.
Photo 27 (below). View north toward Mission Valley Brick Company's Linda Vista mine. Buff and blue-gray mudstone and shale are mined here for use in making brick. Clay material is part of the Rose Canyon shale member of the Eocene La Jolla formation.
terrace. The beveling effect of marine erosion apparently removed the younger Eocene rocks and possibly part of the residual claystone.
Linda Vista Mine
Location: The deposit is in the SE.!4 NW,i/4 Sec. 9, T. 15 S., R. 3 W., S.B.M.; about 4.5 miles west of Mira- mar and U.S. Highway 395. The plant is 0.2 mile south- east of the intersection of Cabrillo Freeway (U.S. High- way 395) and Friars Road in San Diego and 8.2 miles southeast of the deposit. Ownership: Mission Valley Brick Company (R. E. Hazard Construction Company), P.O. Box 3217, San Diego 3, California.
The Linda Vista Clay Deposit was first mined about 1923 by the Vitrified Products Company of San Diego. This company produced about 10,000 tons of clay an- nually for ceramics during the succeeding few years, but production soon dwindled to only a few hundred tons and the property was abandoned prior to 1938. It re- mained idle until 1956 when the mine was reopened by the Mission Valley Brick Company. The present opera- tion is a few hundred yards southeast of the old workings but still within the same clay layer. Total production statistics are unavailable. The present operation yielded about 15,000 tons of clay in 1956.
Clay material is mined from the Rose Canyon shale member of the Eocene La Jolla formation. At the deposit, the base of the member is composed of about 40 feet of alternating layers of buff and gray shale, which is over- lain successively by 10 feet of buff mudstone, 100 feet of buff, manganese-stained shale and 2 to 3 feet of soil. Interbedded with the buff and gray shale is a layer of hard siltstone concretions which range widely in size, but are generally between 1 and 2 feet in greatest dimen- sion. Gypsum (CaS04.2H.O) is common throughout the
San Diego— Mineral Resources
59
Figure 10. Geologic sketch map, Pacific Clay Products mine, East pit.
deposit and may in places compose as much as 10 percent of the rock. The gypsum ranges from thin coatings on fracture planes, to veins an inch or more in thickness. The gypsum appears to be more abundant in and below the concretion layer. The shale member has been folded considerably and dips range from 5 or less to 26 degrees or more. A normal fault of small displacement is exposed in the buff and gray shale beds in the southern part of the deposit (Fig. 9).
The clay has good plasticity, medium high dry strength, and a maximum total shrinkage of 11.2 percent at cone 1 (plastic basis). Some lime is present which causes a yellow-green color at high temperature. The best firing range is from cone 010 to cone 1 (Dietrich, 1928, p. 322).
The clay material is mined from an open pit on the west side of a low hill. The surface is stripped of soil prior to mining and the face undercut by power shovel from a single bench at the base of the cut. The clay material is allowed to slough off on to the floor of the bench where it is mucked into trucks and transported about 12 miles by road to the plant. The open cut was about 550 feet long and 250 feet at its widest point, in November 1957 (Photo 27).
The company controls 22 acres of land around the deposit. The property has been drilled randomly, and the clay layer is said to be 200 feet thick. Reserves are believed to be sufficient for a long-term operation.
At the plant the newly mined clay material is blended with various proportions of sand and finely ground brick rejects. These additives facilitate drying of the bricks prior to firing. The mix is reduced uniformly in size by a hammer mill to pass a l/s by Y2 inch slot screen. Dry barium carbonate and other salts are added to reduce efflorescence caused by the presence of gypsum. The mix is then pugged with water, extruded as a cake, and wire-
cut into bricks. The bricks are loaded on flat trucks, force dried, and fired in a tunnel kiln. Waste heat from the tunnel kiln supplies heat for the drying process. The plant capacity is about 240 tons of clay material or 40,000 finished bricks per day. The company makes the follow- ing shapes and sizes of bricks in both smooth and scratched face:
Type
.Modular face Cored
Modular paver Solid
Standard face Cored
Standard paver _ Solid
Norman face Cored
Norman paver Solid
Mission norman Cored
Jumbo face Cored
Jumbo paver Solid
Size
2lAxi%
v, x v\
V/i x 3 % 2 V2 x 3 % 2 % x 3 V, 2 % x 3 Vi 2 % x 3 '/> VA xi'A xll 3'/2 x3!4 xll
x y
x 7' x 81 x 81 x 11 xll
X ll1
Price
S42 45 42 45 70 70 70 70 80
* Per thousand as of November 1957.
Pacific Clay Products Company (Kelley No. 1) Mine
Location: Nearly in the center of Sec. 15, T. 12 S., R. 4 W., S.B.iM. (Projected); about four miles east-southeast of Carlsbad and one mile west of the Kelley Ranch Mine. Ownership: Pacific Clay Products Company, 1255 West Fourth Street, Los Angeles. The property is pat- ented ranch land and comprises two contiguous parcels, one 20 acres and the other 25 acres.
The mining of ceramic clay at this deposit began in the early 1920's and continued until 1941 when access to nearby railroad facilities was withdrawn. In 1957, the company conducted a rather extensive exploratory pro- gram in this area and mining was resumed or a small scale. Total production figures for the operation are not available, but the size of the workings indicates that pos- sibly as much as 70,000 tons of clay have been mined.
The geologic setting of this deposit is the same as that of the Kelley Ranch Mine and both operations are on the same clay layer. The deposit has been worked by means of two large open pits. The clay layer in the Fast Pit comprises about four feet of red, buff, and white mottled claystone and an equal thickness of brown mud-
Figure 11. Geologic sketch map, Pacific Clay Products mine, West pit.
60 California Division of Mines and Geology [County Report 3
stone. The nearly flat-lying clay layer is in gradational The combined recorded production of both mines is
contact with the underlying greenish-gray shale of Cre- about 23,000 tons valued at about $90,000. The size of
taceous (?) age, and is overlain by about two feet of soil. the workings and the values estimated from concealed
The shale is at least 15 feet thick. Over much of the production records, indicate that these two mines yielded
surface surrounding the pit the soil is veneered with at least 83,000 tons of clay valued at $670,000. The
small, limonite-impregnated fragments of clay, some of Standard Oil Company Mine appears to have been the
which are almost wholly limonite. The East Pit is larger mine.
roughly oval in shape; about 400 feet long in an east- The clay occurs as several beds in a sequence of pale- west direction, and 250 feet long in a north-south direc- gray arkosic sandstones. These beds are part of the San tion (see Fig. 10). It has an average depth of about 10 Diego formation which is middle or upper Pliocene in feet. In 1957 a large trench was dug in an east-west direc- age (Photo 26). The principal clay bed occurs at a tion near the middle of the pit to expose a section of the nearly uniform elevation of 350 feet. This bed averages shale. This cut is about 25 feet wide, 100 feet long and about three feet in observed thickness, and in some ex- 15 feet deep. posures is four feet or more thick. The clay is a relatively The West Pit is about 1,000 feet southwest of the pure activatable bentonite and one sample collected con- East Pit. Here the clay layer has a maximum thickness tains only 4 percent impurities, which are largely sericite of about 20 feet and consists of pink, buff and white and quartz. The highest grade clay is mostly white, mottled claystone. At the west end of the pit the clay cream or pale pink but some of it ranges from dark layer is about six feet thick and unusually white. Much brown to pale pinkish brown. The clay has a soapy of the floor of the pit has been cut in greenish-gray shale consistency when hydrated and becomes powdery when and conglomerate. Overlying the clay layer is about three thoroughly dried. On immersion in water it will expand feet of brown, gravelly soil. This pit is also oval in out- slightly. It has a hardness of about 1 and a dull earthy line (Fig. 11). It is about 400 feet long in an east- west to waxy luster, direction, 150 feet long in a north-south direction and
has an average depth of 10 feet. A small prospect pit is Detailed section of the clay zone, Otay bentonite *
adjacent to, and east of, the East Pit and is cut in the „ Description Thickness
c i Cream to white, soft, waxy clay containing disseminated
same sequence or rocks. . , '. c • , ,. , .
M . spots and coatings or manganese oxide; slightly gritty;
The white claystone was tested by Dietrich (1928, p. fractures on curved surfaces to thin plates 6 inches
296) and found to be a buff -burning, high plasticity clay. Dark pinkish brown, waxy clay, stained with manganese
It has a total linear shrinkage at cone 15 of 17.9 percent oxide; gritty granular fragments of calcium carbonate
(plastic basis): the softening point is cone 29 and the best °ccu,r on fracture planes—- - 7 inches
r- ■ r , ° iri-»-.u-L/ir>-io Grayish-brown to grayish-green waxy clay 6 inches
firing range from cone 1 to cone 15. Dietrich (1928, Light gray, hard, granular clay; fractures unevenly, con-
p. 322) found the buff claystone to be plastic, to have a tains biotite and manganese stains and calcite in small
high dry strength, and to contain 4.8 percent of + 200 granular pods 9 inches
mesh sand. The clavstone is red-burning and has a long Light grayish-brown, gritty clay 5 inches
vitrification range. Maximum shrinkage was found to be Ught gra^ imPure' sand7 cla^ contains abundant bio-
, _ _ „ / , ■ , • s -r* i c ■ tite, some garnet and ierromagnesian minerals 12 inches
18.9 percent at cone 9 (plastic basis). The best firing Light grayish.brown? gritty cIay 7 inches
range is from cone 02 to cone 13, but bloating begins
above cone 5. Total 4 feet, 4 inches
* Locality about 1 mile west of the mine. Standard Oil Company (Filtrol) Mine
Location: SW.% Sec. 17 and SE.J4 Sec. 18, T. 18 S., The Otay bentonite, as indicated by the presence of
R. 1 W., S.B.M.; on the north slope of Otay Valley, relic ash structures, was derived from one or more vol-
three miles east of Otay. Ownership: Standard Oil Com- canic ash falls. The ash appears to have fallen both on the
pany of California, 605 West Olympic Blvd., Los Ange- land and on the sea. The water-laid ash may be repre-
les (1957). sented in the Otay area by the principal clay bed. This
The deposit was opened and worked briefly as a source bed is relatively free of clastic impurities, whereas other of bentonite by the General Petroleum Company in 1925. bentonite beds above and below it are considerably con- It was bought bv the Standard Oil Companv about a year taminated.
later and operated by this companv through 1944. In , °Pe" P" ™ethods were used exclusively to mine the
,„,, . r-, , ^ ' , j -ii j i clav. Broad benches as much as 1,000 feet wide and
1946, the Hltrol Corporation extensivelv core-drilled the J . , , tnn , , . . . .
. .. . "L _ , , vertical faces up to 100 feet high were cut into slopes,
property and an adjacent area on the Otay Ranch, and These faces ^ oyer 3 fe£ , and the excaFva.
in January of 1947 leased the property from the Stand- dons coyer seyeral acres Clay was hand]ed in the kter
ard Oil Company. A small tonnage of clay was mined in years of the operation bv modern earth moving equip-
1947 and a large tonnage in 1948, but shortly afterward ment and shipped by truck and rail to the El Segundo
the Filtrol Corporation terminated its lease. For some plant of the Standard Oil Company for processing,
years the recorded production of this mine was com- In general, the uses of Otay bentonite have been de-
bined with that of the General Petroleum Mine, nearby. pendent upon its adsorptive properties, and the petro-
1963] San Diego— Mineral Resources
Table 3. Chemical Analyses of Ofay Bentonite.
61
Si02
khO,
Fe203
FeO
MnO
UgO— -
CaO
K20
Na20
P205
Ti02
Carbon tr. H*0— ....
H20+
Ignition loss.
Total
52.52 16.10 .51 .26 .003 5.69 .47 .23 .82
.16
14.68
8.16
99.603
50.30 15.96
6.53
1.24
.45
1.19
23.61
100.14
3
49.56
15.08
3.44
.01
7.84 1.08
.40
22.96
100.37
63.04
18.44
1.20
.01 7.30 .08 .02 3.40 .05 .14
6.47
100.15
5
55.68 17.66 0.96
7.23 1.37 0.50 1.32
13.96
98.68
51.19 15.13 0.86
7.19
1.00
.12
.73
.16 15.80
7.57 99.75
Sample 1. Kerr and others, (1950a, p. 53) 2, 3. Ross and Hendricks (1945, p. 34)
4. Osthaus (1955, p. 96)
5. Schroter and Campbell (1940, p. 6)
6. Speil and others, (1945, p. 11)
leum industry has used it for cleaning heavy lubricating oils, kerosene and gasoline. In addition the Otay clay has proved suitable in oil well drilling mud, paint (filler), water softener compounds, and cleaning compounds. It might also be useful as an insecticide carrier, soil condi- tioner and as an additive in cattle feed.
Union Brick Company Mine, East Pit (Union Brick and Tile Company)
Location: In N.'/2 NE.'/4 Sec. 6, T. 16 S., R. 3 W., S.B.M. (projected); about 7.5 miles northwest of San Diego Civic Center and about 3.5 miles southeast of La Jolla, on U.S. Highway 101 on the east side of Rose Canyon. The plant is in SW.1/ NE.!4 Sec. 6, T. 16 S., R. 3 W., S.B.M. (projected) about 0.25 mile southwest of the deposit. Ownership: John W. Rice, Jr., Rambla de las Flores, Rancho Santa Fe, California. The property comprises about 220 acres of patented land.
The Union Brick Company Mine was opened about 1947, as a source of ceramic clay, and production through 1956 totaled 248,913 tons valued at 191,976 dollars. This company had mined at two other localities in Rose Can- yon prior to the opening of the present workings. A deposit directly west of the plant was abandoned about 1947 (see Union Brick Company Mine, West Pit in tabu- lated list) and another, 2.5 miles north, near Elvira Sta- tion, on the Santa Fe Railroad, was abandoned about 1941. The latter locality was also the site of a brick plant which was operated for a short time by the Union Brick Company. Prior to its operation by the Union Brick Company the property was known as the Sunnyside Brick and Tile Company (see Union Brick Company Mine, North Pit in tabulated list and Fig. 12).
The Union plant occupies a site that has been a brick- yard for 70 years or more. In 1888 the leaning smoke- stack, which was a familiar landmark in Rose Canyon, was constructed as part of an early brick plant. About 1912 the Union Brick Company moved from its location at the intersection of Harbor Drive and Crosby Street in San Diego to Rose Canyon, and brick and other clay products have been produced there continuously since. In addition to the Union Brick Company, the Rose Can- yon Brick Company, the Hieatt Brick and Tile Com- pany, the Hubbard Brick Company, the San Diego Vitri- fied Brick and Clay Products Company, and the San Diego Brick and Clay Products Company, have all mined clay and produced structural clay products in this area, but are now inactive.
Clay material is mined from a low hill composed prin- cipally of the Rose Canyon shale member of the Eocene La Jolla formation. The clay material is exposed over many tens of acres. The shale is nearly flat-lying and is overlain by a few feet of terrace deposits which contain pebble-to-boulder size clasts, which in turn are overlain by a thin soil covering. The Rose Canyon shale in this area comprises about 75 feet of pale to dark gray mottled mudstone overlain by about 175 feet of light buff-colored mudstone. These rocks are principally mixtures of clay,
30
blue- gray mudstone Rose Can yon shale )
Figure 12.
EX PLANATION Attitude of bedd ing
FEET Approximate Sea le G B. Cleveland Geologic sketch map, Union Brick Company mine, North pit.
62
California Division of Mines and Geology
County Report 3
Figure 13. Geologic sketch map, Union Brick Company mine, East pit.
Photo 28. General view southeast of lower Rose Canyon, showing op- erations of the Union Brick Company. Clay is mined from a large open pit on the east side of the canyon and transported to the plant (arrow) by 'Carryall. Clay is in Rose Canyon shale member of the Eocene La Jolla formation. Large buildings in center are warehouse facilities of Convair Aircraft Company.
and silt-size fragments of quartz, and biotite. Both the buff and gray clay materials are used. They are mined by open pit methods on irregular benches by carryall and transported one quarter of a mile to the plant. In October 1957 the open cut was about 800 feet long and about 500 feet wide (Fig. 13, Photo 28).
At the plant the clay is reduced to minus Vi-mch in a primary crusher, ground in a dry pan mill and delivered to a screw-type pugging and extrusion machine. Water containing barium compounds is added to the clay to reduce scumming in the finished brick. Two hundred pounds of barium carbonate, which is imported from Germany, is mixed with each 500 gallons of water used. A vacuum of 24 pounds per square inch is maintained to remove any air that may be trapped in the mix. The bricks are wire cut from a continuous bar of clay extruded from the pugging machine. Different dies are used to produce the various shaped bricks made by the company. The wet bricks are dried five to six weeks in the sun or for a shorter time in fan-ventilated sheds and hot air dryers. After drying, the bricks are fired in field (scove) kilns for six days or for 24 hours in a shuttle kiln (Photo 25).
The plant processes approximately 16, eight-yard loads, or about 200 tons of clay, per day. It has a capacity of 80,000 bricks per eight-hour period. The company pro- duces Standard (8x3% x2'/2 inches), Norman (\\V2 x 3 % x 2 1/2 inches), Oversize ( 1 1 x/i x3!4 x3'/2 inches), and "Brik-Blok" (11 '/z x 5l/2 x 3'/2 and 15'/2 x 7'/2 x 3/2
963]
San Diego— Mineral Resources
Cloy
63
Name of c/o/'m, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
American En- caustic Tile Company (Amer- ican Encaustic Tiling Company West Coast Tile Company)
American Pottery Company
Atlas Brick and Clay Company mine
Bay View Fuel Company mine
California China Clay Products Company (Calif ornia China Products Com- pany)
California Clay Products Com- pany (Mission China Company, Southern Cal- ifornia Clay Products Com- pany)
California Clay Refining Com- pany mine
Clay prospect
Crystal Silica Co.
Dinero Ranch Clay deposit
Dorothy and Pearl claims (Pearl and Dorothy claims. Pearl and Dorothy Ann claims)
El Cajon Kaolin deposit
Undetermined (1957) .
Undetermined (1958) .
Undetermined (1958) .
Undetermined
(1958) San Diego (1942)
Undetermined (1958) .
Undetermined
(1958) Los Angeles (1928).
Otay Valley area.
SE^ sec. 30, T8S, R6W, SBM; on the south side of Talega Can- yon, in the Camp Pendleton Naval Reserva- tion, about 4 miles northeast of San Clemente.
Oceanside area.
Gladding, McBean and Co. , Los Angeles (1957)
Undetermined (1958)
Undetermined (1958)
Undetermined (1958)
Bay View Fuel Co. , 10983 Clover Ave. Lynwood (1942)
Undetermined (1958)
Undetermined (1958)
Undetermined (1958)
Within Camp Pendle ton Naval Reser- vation (1958)
'W*s sec. 4, T13S, R 3W , SBM ; 5 miles northeast of Cardiff.
NW^t?) sec. 36, T14S, R1E, SBM; about 7 miles northeast of Lakeside .
Undetermined (1958) California Clay Products Company (1925)
Undetermined (1958)
clay zone 30 ft. thick, which is exposed at the head of a narrow canyon, is overlain by 150 ft. of light colored sandstone. It is red, yellow, yellowish-brown, gray and white; sandy; and fleck- ed with pearly plates of anauxite ( ?) .
Red, buff and white residual clay- stone is exposed on south side of low hill. Clay appears to be de- rived from greenstone by weather- ing. Workings consist of two adits which have a common portal: one bearing N5E, about 25 ft. long; the other bearing N30W, about 15 ft. long; and one small open cut about 100 ft. above the adits. The alteration zone appar- ently covers many acres.
The following is taken from
Dietrich's (1928, p. 201) des- cription: "The kaolin was formed by alteration in situ of an alas- kite or similar pegmatitic deriv- ative, containing but small quan- tities of ferro-manganesian miner als. The extent of alteration varies widely within comparativel; r short distances, so that the re- sultant material ranges from slightly-plastic kaolin contain- ing an excess of free quartz and undecomposed feldspar, to extreme- ly plastic, fine-grained
No longer operating in county. Known as West Coast Tile Company prior to 1920. See also under "Feldspar" in tabulated list. (Boalich ^t al . 20:62) .
No longer operating in county. See El Cajon Kaolin deposit. (Tucker 25:354).
No longer operating in county (1957) . See Union Brick Company mine, North Pit. (Symons 28:264) .
No longer operating in county (1957) , Formerly a producer of crude clay. (Symons 43:154) .
No longer operating in county. See El Cajon Kaolin deposit. (Merrill 14: 687; Boalich et al . 20:93).
No longer operating in county. See El Cajon Kaolin Deposit; Dorothy and Pearl claims; and Robert Charles and Thomas Hewitt claims. (Dietrich 28: 201 ; Tucker 25:354) .
No longer operating in county. Small production 1923 to 1925. Patented land. (Tucker 25:360).
Deposit is in southern extension of Tierra Colorado Clay District, Orange County. (Stauffer 45).
In 1958 Gladding, McBean and Co. was purchasing clay obtained from settlmc ponds of Crystal Silica Co. sand operation. See description in text under "Specialty sands."
See General Petroleum Company mine. (Tucker 21b: 375) .
Patented placer claims. Ceramic prop- erties reported by Dietrich. Was used with other clay to make chemical stoneware. Long idle. Borders Robert Charles and Thomas Hewitt claims on east(?). (Dietrich 28:201, 311; Tucker 25:355; Tucker and Reed 39:33) .
Deposit has not been operated since 1916. "It has been developed by a number of tunnels, shafts, and open cuts, the principal tunnel having been driven in a northwesterly direction for a distance of 75 feet, to a point 50 feet below the surface. This tunnel is connected by means of a raise to a small open pit, or glory hole. The material exposed by these workings shows all of the variations indicated above, with six feet of thoroughly altered plastic kaolin near the face. During 1914 and 1916, some kaolin from these workings was
64
California Division of Mines and Geology
Clay
[County Report
Map
No
Name of claim, mine, or group
Owner (Name, address)
Geology
Remarks and references
tf-,;
El Cajon Kaolin deposit (Continued)
Fil trol Corpor- ation
General Petro- leum Company mine (Mosto Ranch deposit, Mosto Otaylite deposit. Ham- burger Co. , Dinero Ranch Clay deposit)
Gladding, McBean and Company mine
Hamburger Com- pany
Hieatt Brick and Tile Co.
Hubbard Brick Co Co.
Huchting Ranch deposit
Jamul Ranch deposit
Kelley Ranch
mine
thor oughly-hydrated kaolin. Ex- posures of such material have been made at various points on the mountain, indicating that they occur in a zone that has a general northeast strike."
NH sec. 30 and NW^ sec. 29, T18S, R1W, SBM; on the south side of Otay Valley, 3 miles east of Otay.
NW^SE** sec. 7, T13S, R3W, SBM (proj .) ; ad- jacent to Vitri- fied Products Co. mine, one mile north of Olivenhain and 4 miles east of Encinitas.
C. A. Butler,
499 Hilltop St. ;
Henry W. Albert 74 E St. ;
L. B. Waller,
Box 725, all of Chula Vista (1958)
Undetermined (1958)
Gladding, McBean and Company (1928)
White, pink, and brown waxy clay occurs in bed 2 to 4 ft. thick interbedded with flat-lying arko- sic sandstones along south side of Otay Valley. Beds are in upper part of San Diego formation which is middle or upper Pliocene in age. See description of Standard Oil Company mine in text.
About 30 ft. of red and white mot- tled sandy claystone is exposed on the east side of a low hill. Clay was mined from a pit 100 ft long and 50 ft. wide. The clay layer is overlain by about 3 ft. of greenish-gray shale; its base is not exposed.
Unable to locate (1958)
NE^ sec. 25, T13S R4W, SBM; near La Costa Sta- tion, Santa Fe Railroad (1914) .
Undetermined (1957).
East-southeast of Carlsbad.
Undetermined (1958!
Undetermined (1957)
shipped to the faience tile plant of the former California China Clay Products Company at National City. The total quantity shipped probably did not exceed 400 tons, to judge fro the extent of the workings. The material was packed by mules over a rough and steep trail to a point on the San Diego River, then hauled by wagon to Lakeside, at a cost said to have been $7.50 per ton, exclusive of mining. " (Dietrich, 1928, p. 201) . (Aubury 06:227; Dietrich 28:201, 259; Tucker 25:354; Tucker and Reed 39:33)
See Standard Oil Company mine in text. (Jenkins 50:380) .
Mine yielded several tens of thousands ' of tons of high-grade bentonitic clay during the 1920's. Material was used as an adsorbent in petroleum refin- ing. The mine was developed by cut- ting back slopes and forming benches 50 to 200 feet wide to provide a working and storage area. These areas were developed laterally for 4,500 ft. A series of adits was driven southward into the face of the cut and laterals were driven from the adits into the clay bed. The clay was moved to the floor of the cuts and allowed to dry. The clay was loaded into trucks and hauled to Palm City for rail shipment to Los Angeles. (Aubury 06:227; Cleveland 60:1-16; Goodyear 90:139; Newman 23:100; Symons 29a:171; Tucker 25:360).
Property yielded 5000 to 7000 tons of clay annually in mid-1920 's. Formerly operated by L. A. Pressed Brick Co. Ceramic properties reported by Dietrich. Idle in early 1958. (Dietrich 28:202, 322).
See General Petroleum Company mine. (Tucker 25:360) .
No longer operating in county. See Union Brick Co. ; Kelley Ranch deposit (Merrill 14:686) .
No longer operating in county. See Union Brick Company mine. East pit, in text. (Aubury 06:254; Merrill 14: 686) .
Yellow-burning non-plastic clay. (Merrill 14:687) .
Bentonitic clay mined briefly by Otay- lite Products Company and sold in Los Angeles for cleaning compound, water softener and as a filler in paint. (Tucker 21:376).
See text.
[963
San Diego— Mineral Resources
65
Clay
Map No
Nome Of c/o/mf mine, or group
Owner (Name, address)
Geology
Remarks and references
Kiellar Ranch deposit
La Jolla Clay Products Comp- any
Undetermined (1957)|Undetermined (1957) East of Cardiff.
Linda Vista deposit
Los Angeles Pressed Brick Company mine
Merrick Kaolin deposit
Mission China Company (Calif ornia Clay Products Com- pany)
Mission Valley Brick Co. (R.E Hazard Con- struction Com- pany)
Morris Clay deposit
Morton Clay deposit
Mosto Ranch deposit
National Brick Company
Old Mission Tile Company
Otaylite Prod- ucts Company
Pacific Clay Products Com- pany (Kelley No. 1) mine
Pearl and Doro- thy claims
R. E. Hazard Construction
Co.
SE^ sec. 24, T15S, R4W, SBM (proj.) 2 miles north- east of La Jolla, on Torrey Pines Road.
West of Miramar.
Mr. Cornalio Rod- riguez , P.O. Box 712, La Jolla (1956)
'A deposit of red and mottled clay" (Tucker, 1921) .
About 25 ft. of nearly flat lying buff and blue-gray mudstone as ex- posed on the southside of a small canyon. Clay material occurs in the Rose Canyon shale member of the La Jolla formation which is Eocene in age.
N^NW^NW^ sec. 36, T14S, R1E, SBM; 2 miles south- east of Barona, on the west flank of El Ca- j on Mt .
Undetermined (19581
NW^SW^a sec. 18, T12S, R2W, SBM; about 2 miles southeast of San Marcos.
Undetermined (1958) .
2500 Hoover Ave. National City.
Undetermined (1957) .
East-southeast of Carlsbad.
Undetermined (1957)
Owned by Michael Merrick, Barstow (1939)
Undetermined (1958)
H. B. Jenne, Jesmond Dene
(near Escondido)
(1958)
Undetermined (1958)
Morgan Everding, Concrete Company, 2500 Hoover Ave. , National City (1958)
Buff, dark-red and white clay is poorly exposed in a zone 20 to 40 ft. wide and about 200 ft. long. The zone strikes N60°E. The clay may be a product of hydrothermal alteration along a fault.
Bentonite in a bed at least 30 ft,, thick forms a low rounded hill in a saddle between ridges of tona- lite. The clay is impure, green- ish gray and forms a cracked soil
Tidal flat deposit of reddish- brown, micaceous, silty mudstone.
In 1920 the deposit was being developed by the St. Luis Fire Brick Company, and shipments were being made to the company's plant in Los Angeles. (Tucker 21b: 375) .
Clay material mined from small open cut and fabricated by hand. Fired in woodburning circular brick kiln. Clay material is mixed only with water, dried for 6 weeks, and fired for 18 hours. Ornamental pottery, flowerpots, water jugs, plates, roof- ing tile and chimneys are produced and sold on the property. About one ton of clay is mined per month. (Jenkins 50:380) .
Formerly operated by Vitrified Products Company. See text. (Dietrich 28:205, 322; Tucker 25:357; Tucker and Reed 39: 34).
See Gladding, McBean and Company mine. (Tucker 25:355) .
Property patented but has been long idle no production. Developed by two small prospect pits. Because of poor acces- sibility and small size, the deposit is of little commercial interest. (Tucker and Reed 39:33).
No longer operating in county. See Robert Charles and Thomas Hewitt claims and California Clay Products Companv. (Dietrich 28:201; Tucker 25 355).
See Linda Vista deposit in text.
A mill was built on property prior to 1928 but attempts to make brick and other ceramic ware were unsuccessful . Long idle. (Dietrich 28:202, 348; Tucker 25:355) .
Undeveloped (1925) . Published informat- ion on location incomplete. (Tucker 25:355; Tucker and Reed 39:33).
See General Petroleum Company mine.
No longer operating ill county. Clay
deposit long idle; site being used
for concrete products plant. (Diet- rich 28:203; Tucker 25:356).
No longer operating in county. (Dietrich 28:203; Symons 28:265).
No longer operating in county. See Jamul Ranch deposit. (Tucker 21:376)
See text. (Dietrich 28:203, 322;
Tucker 25:356; Tucker and Reed 39:33)
See Dorothy and Pearl claims.
See Linda Vista deposit in text.
66
California Division of Mines and Geology
Clay
[County Report
Map No
Name Of claim, mine, or group
Location
Owner (Name, address/
Geology
Remarks and references
Robert Charles and Thomas Hewitt claims
Rose Canyon Brick Co.
Saint Luis Fire Brick Company
San Diego Brick and Tile Com- pany mine (San Diego Tile and Brick Company; Sunnyside Brick and Tile Com- pany)
San Diego Vitri- fied Brick and Clay Products Co.
Schier Clay deposit
SW\ sec. 4, T13S, R3W, SBM; about 2'^ miles north- east of Oliven- hain and 5 miles northeast of Cardiff.
Theodore and Fran cis Koons, Route 2, Box 257 3 Encimtas (1958)
Sorrento Brick and Clay Products, Inc. mine
Southern Calif- ornia Clay Products Company
Standard Oil Company (Filtrol) mine
Stell Clay deposit
Sunnyside Brick and Tile Co. (San Diego Brick and Tile Company)
Thebo and Cogens deposit
Union Brick
Company mine, East Pit (Union Brick and Tile Company)
Undetermined (1958) .
NE^ sec. 23, T10S, R4W, SBM; about 2 miles west of Bonsall.
SWij sec. 5, T15S, R3W, SBM (proj.); about 5 miles southeast of Del Mar, in Sole- dad Canyon.
Buff and white residual claystone is exposed in a small open cut. Clay was derived from greenstone by weathering. Area of alteration covers many acres.
Undetermined (1958) .
3 miles east of Otay.
Undetermined (1958) .
Undetermined (1958) .
About 7-3/4 miles northwest of San Diego Civic Center.
Undetermined (1958)
Samuel S. Schier, P.O. Box 108, Bonsall (1958)
Sorrento Brick and Clay Products Inc. ,
10505 Sorrento Valley Road, Sorrento (1957)
Undetermined (1958)
Undetermined (1958)
Dark grayish-brown impure benton- ite(?), a few ins. to a few ft. in thickness, underlies an area of about one acre. Clay is overlain by 10 ft. of tuff and an undeter- mined thickness of dacite flows. Country rock is Cretaceous Bonsall tonalite.
Buff and bluish-gray mudstone of the Rose Canyon shale member of the Eocene La Jolla formation crops out on the north and south slopes of Soledad Canyon. The clay layer is about 20 ft. thick where exposed in an open cut on the Sorrento property. The clay is relatively pure and contains only small amounts of soluble salts. A few large manganese- stained concretions occur with the clay.
Property comprises two patented 20-acre placer claims and adjoins Dorothy and Pearl claims on the west(?). See Mission China Company. (Tucker 25: 355).
No longer operating in county. See
Union Brick Company Mine, East Pit, in text. (Aubury 06:254; Merrill 14:686!
No longer operating in county. See Kiellar Ranch deposit. (Tucker 21b: 375) .
No longer operating in county. See Union Brick Company mine. North Pit, in text. (Dietrich 28:203; Tucker 24:368; 25:356) .
No longer operating in county. 14:686) .
(Merrill
No production. Clay layer has been
prospected by numerous bulldozer cuts.
Deposit was opened in late 1956 and mining continued until August 1957. Clay was mined from an open cut 100 ft. long in an east-west direction and 75 ft. long in a north-south direction. A ceramic plant adjacent to the pit produced common brick, face brick and flower pots during 1957. Production has been curtailed and only flower pots were being made in late 1957. Clay for this use was drawn from a stockpile.
No longer operating in county. e_t al. 20:93; Tucker 21b:375)
(Boalich
See text. (Cleveland 60:1-16; Symons 30: 171).
Production in 1913. (W. B. Tucker, unpub. Div. of Mines field report, 1920) .
No longer operating in county. See Union Brick Company Mine, East Pit. (Merrill 14:686; Boalich et al . 20:93; Dietrich 28:203) .
No recorded production. (Boalich et al . 20:93) .
See text.
963
San Diego— Mineral Resources
67
C 1 ay
Map
No
/Vome <?/" claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
- o 25
Union Brick
SW^NW^ sec. 30,
King Van Lines,
About 25 ft. of bluish-gray clay-
Idle since about 1941. Ceramic proper-
Company mine.
T15S, R3W, SBM
5129 Weeks St. ,
stone is overlain by about 250 ft.
ties of the clay were reported by
North Pit (San
(proj . ) ; about
San Diego (1958)
of buff shale and mudstone of the
Dietrich. (Dietrich 28:203, 339;
Diego Brick
h mile southwest
Eocene Rose Canyon shale. The
Merrill 14:686) .
and Tile Com-
of Elvira stat-
clay layers are nearly flat lying
pany, Sunny-
ion on Santa Fe
except the lower part of the clay
side Brick and
Railroad and
layer which is folded into an
i
Tile Company)
just off U.S. Highway 101 on the west side of Rose Canyon.
east-plunging anticline. See geologic sketch map in text.
26
Union Brick Com-
SW^NE^s sec. 6,
John W. Rice, Jr.,
Nearly flat lying beds of brown
Deposit idle since 1947. Ceramic prop-
pany mine, West
T16S, R3W, SBM
Rambla de los
claystone, with numerous lenses of
erties of the clay were reported by
Pit (Rose Can-
(proj . ) ; about
Flores,
brown pebble to cobble conglomer-
Dietrich. (Aubury 06:375; Boalich
yon Brick Com-
7'. miles north-
Rancho Santa Fe
ates and sandstone, are underlain
et al. 20:94; Dietrich 28:204, 340;
pany, Hieatt
west of San
(1958)
by bluish-gray claystone.
Merrill 14:686; Tucker 21b:375; 24:
Brick and Tile
Diego Civic
369; 25:357; Tucker and Reed 39:34).
Company, Hub-
Center.
bard Brick
Company, San
Diego Vitrifiec
Brick and Clay
Products Com-
pany, and San
Diego Brick
and Clay Pro-
ducts Company)
Unnamed
Lyons Peak
Undetermined (1957
(Lyons Peak is in S^ sec. 10 and N^2 sec. 15, T17S, R2E, SBM; about 7 miles east of Jamul ) .
Report of clay at this locality appears to be unfounded. (Merrill 14:687) .
Unnamed
Poway Peak
Undetermined (1957) .
Poway Peak could not be located on
present topographic maps. (Merrill 14:687) .
Unnamed
San Vicente Mountain
Undetermined (1957) .
San Vicente Mountain could not be
located on present topographic maps. (Merrill 14:687) .
»
27
Vitrified Pro-
NW^SE^ sec. 7,
Undetermined (1958)
No longer operating in county. See
ducts Co. mine
T13S, R3W, SBM
Linda Vista mine in text. (Dietrich
(Vitrified
(proj . ) ; one
28:205; Jenkins 50:380; Tucker 24:369;
Clay Products
mile north of
25:355, 357; Tucker and Reed 39:34).
Co. , Wiro
Olivenhain and
Mines)
4 miles east of Encmitas.
West Coast Tile
No longer operating in county. Known as
Company (/Amer-
American Encaustic Tile Company after
ican Encaustic
1920. See El Cajon Kaolin deposit
Tile Company,
herein and McGinty Mt. , under "Feld-
American En-
spar." (Boalich et al. 20:93).
caustic Tiling
Company)
Wiro mines
See Vitrified Products Company mine. (Dietrich 28:205) .
68
California Division of Mines and Geology
[County Report
Figure 14. Geologic sketch map, Vitrified Products Company mine.
inches) smooth or scratch face brick. The prices as of October 1957 were 40, 55, 60, 95 and 165 dollars per thousand, respectively.
A separate organization headed by Leo Delgado, proc- esses the damaged and warped bricks from the main plant at a small operation on the Union property. The material is crushed to minus one-half inch, packaged in 100-pound bags, and marketed in the San Diego area for roofing granules. The price in October 1957 was $1.25 per hundred pounds.
Vitrified Products Company Mine (Vitrified Clay Products Co., Wiro Mines)
Location: NW.'/4 SE.!4 Sec. 7, T. 13 S., R. 3 W., S.B.M. (projected); one mile north of Olivenhain and four miles east of Encinitas. Ownership: Vitrified Prod- ucts Company, San Diego (1942). The property com- prises 16.6 acres of patented ranch land.
This deposit was a source of ceramic clay from about 1924 until about 1942. Although its total yield must have been many thousands of tons, no total production figures are available.
A clay layer is exposed in what appears to be an inlier cut through the nearly flat-lying beds of the Del- mar sand member of the Eocene La Jolla formation. The best exposure of clay and the locality where it was mined, is on a north-trending ridge near the head of a small tributary of Escondido Creek. Headward erosion of this creek has exposed the clay along gentle slopes below an elevation of about 140 feet. Above this elevation the resistant beds of the Delmar sand are preserved.
The clay layer crops out discontinuously over an area of several tens of acres. The zone that contains the clay layer consists of a lower 20 feet of sandy, white to buff mottled claystone overlain by about 18 feet of lavender and buff mottled claystone. Blotches of reddish-brown limonite are conspicuous on the weathered surface of the clay. The clay layer grades downward into a coarse ar- kose and pebble to cobble conglomerate. It is overlain by two feet of buff sandstone and four feet of greenish- gray shale, both of which may be part of the Delmar
sand, and soil. In the vicinity of the clay pits the strat; are gently folded into a small anticline that plunges t< the southwest (Fig. 14).
The clay has been mined from two open pits oi the west face of the ridge. The more southerly pit is th largest and is nearly oval in outline. It trends north an( is about 200 feet long and about 100 feet wide. The cla) zone in this pit is about 30 feet thick and dips 10 degree to the southwest in the southern half of the pit. Tb more northerly pit also is roughly oval in outline am trends northeastward. It is about 120 feet long and 8< feet wide. About 20 feet of red and white claystone i exposed on the east face of this pit. It is overlain by few feet of buff colored sandstone, sandy green shale anc soil. The clay layer dips about 10 degrees to the north west.
One clay sample had a medium-high dry strength weak plasticity and contained 41 percent (4-200 mesh sand. The total linear shrinkage (plastic basis) was 8.( percent at cone 13. The best firing range was from com 1 to above cone 13 (Dietrich, 1928, p. 287). Anothe sample tested by Dietrich (1928, p. 288) showed nearh the same properties except it contained 31 percent 4-201 mesh sand, a linear shrinkage at cone 15 of 11.5 percent and its best firing range was from cone 1 to cone 15
COAL
Commercial deposits of coal are not known to occu in San Diego County. The only reported occurrence in the county are brown lignite 10 miles north of Sai Diego (Hanks, 1882, p. 240) and carboniferous shale a Torrey Pines State Park (Roy Kepner, San Diego Count) Division of Natural Resources, personal communication 1958).
COBALT
Cobalt occurs at the Friday Mine and at the Old Iron sides Prospect, which are described herein unde "Nickel."
COLUMBIUM-TANTALUM
Columbium-tantalum bearing minerals are uncommoi to rare constituents of the pegmatite deposits of Sat Diego County. Tantalum ore from the county is listec with Unapportioned under recorded mineral productioi for 1920 (see Table 1).
COPPER *
Only an extremely small part of the copper productioi of California has come from deposits in San Dieg< County. The total recorded production for the count} is slightly more than 300,000 pounds, of which slighth more than 100,000 pounds was produced from or custom-milled at the Owens and Eagle Gold Mines, ii 1904 and 1938, respectively. The source of this ore wa not determined bv the writers.
L
By F. H. Weber and R. M. Stewart.
1963]
San Diego— Mineral Resources
Cool
69
l
MJP
Name of claim,
Owner
Geology
Remarks and references
ti No
mine, or group
(Name, address)
Torrey Pines
Sec. 2 5 or 36,
California Div.
Carbon-bearing shale has been re-
(Roy Kepner , San Diego Div. Nat. Res.,
j:
Beach State
T14S, R4W, SBM
Beaches and Parks,
ported from the cliffs at the
personal communication, 1958) .
Park
(proj . ) ; in sea cliffs along
State of Calif- ornia ,
north end of the park.
beach.
Sacramento, Calif.
1
Unnamed
See "Remarks. . . "
Hanks (1882) reported that an Oak-
Hanks (1882) stated that the deposit
land capitalist was developing a seam of brown lignite that ranged in thickness from 3 to 5 ft.
was "on the sea shore about 10 miles north of San Diego" . No additional published information. (Hanks 82:
1
"that could be traced for a long
240) .
distance" .
1
Cobalt
'Map No
Name of claim, mine, or group
Location
Owner (Nome, address)
Geology
Remarks and references
Friday mine
Old Ironsides prospect
— — — — ^^-^-^—^—
See text under "Nickel". See under "Nickel".
The only two deposits that have been mined mainly or copper are the Daley Deposit, south of Ramona, and he Encinitas Deposit, north of Rancho Santa Fe (see descriptions below). The Daley Deposit is reported to lave yielded 175,000 pounds of copper during World War I, when the price of copper jumped from 17 cents aer pound in 1915 to 27 cents by 1917. The Encinitas Deposit yielded about 12,000 pounds of copper from ore nined in 1905 and during World War I.
Deposits that have been prospected primarily for cop- aer also are in the Defiance District which is in the xtreme northwest part of the county, and partly in liverside County. These deposits, which are listed under he "Defiance District" in the accompanying tabulated ist, have not been mined.
Two deposits that contain significant proportions of copper are described under "Nickel." These are the Friday and Old Ironsides nickel-cobalt-copper bearing bodies which probably average between % and 1 percent copper.
Daley (Barona) Mine
Location: Sec. 11, T. 14 S., R. 1 E., S.B.M. (pro- jected); about five miles south of Ramona, on the Canada de San Vicente y Mesa del Padre Barona. Ownership: Bank of America, Union Title and Trust Co., and Ed. and Florence Lindsay (address undetermined) own 100 acres of patented property (1958).
The Daley Deposit was discovered in 1 894, and worked from 1915 to 1916 by the San Jacinto Mining and Milling Company, and from 1916 to 1919, or slightly longer, by the Southern California Mining and Milling Company, San Diego. The ore mined was smelted in a 50-ton re- verbatory furnace on the property. The combined pro- duction of the two companies was about 175,000 pounds of copper, of which about 1 50,000 pounds was produced
in 1917, when the price of copper reached a peak of 27 cents a pound.
The Daley Deposit lies in a terrace-like area on the northwest side of a small hill which slopes steeply west. The hill is one of several which lie east of a vallev that contains the headwaters of Daley Creek. The deposit consists of a north-trending zone of copper-bearing min- eralization which was reported by Tucker (1924, p. 370) to be 150 feet long and 50 feet wide. The zone occurs in a north-trending pendant of schist which is bordered by granitic rocks. Oxide minerals in the upper 30 feet of the deposit consist of limonite, black copper oxides, malachite, and azurite. Finely divided chalcopyrite, with pyrite, occurs below the oxide zone. The ore probably averaged between 2 and 3 percent copper, and six ounces of silver per ton.
The principal working is a vertical shaft that was sunk along the west edge of the terrace-like area to a depth of about 115 feet. Level workings are appended to the shaft, and shallow surface workings flank the collar of the shaft. An additional working is an adit of undetermined length which extends eastward toward the bottom of the shaft from a point on the side of the hill, about 750 feet due west of, and 125 feet lower than, the shaft's collar.
Encinitas (Danes Lea) Mine *
Location: SE.'/4 Sec. 32 and SW.>/4 SW.'/4 Sec. 33, T. 12 S., R. 3 W., S.B.M.; and NW.'/4 Sec. 4 and NE.1/, NE.'/4 Sec. 5, T. 13 S., R. 3 W., S.B.M.; nearly four miles north of Rancho Santa Fe. Ownership: R. S. Per- kins, 1376 San Ysidro Drive, Beverly Hills, owns 10 northwest-trending, contiguous, patented claims which comprise 133 acres (1955).
The Encinitas Deposit was discovered in 1887 and worked sporadically from that year until about 1917,
* Prepared by F. H. Weber from data gathered mainly by R. M. Stewart.
70
California Division of Mines and Geology
[County Report
Copper
Mop
Name of claim,
L oca t ion
Owner
Geology
Remarks and references
No
mine, or group
(Name, address)
28
American Girl
North edge SE*s
Undetermined (1958)
Shear zones in Santiago Peak meta-
Explored by shallow cuts and 100-ft.
prospect
sec. 1, T8S, R6W
volcanic rocks contain bodies
adit. Claim located after previous
SBM (proj . ) ;
W. A. Clark (?) ,
which contain copper sulfide and
claims in Defiance district, as liste
Defiance dis-
Fallbrook (1914)
oxide minerals .
by Hubon (1902) , had become invalid.
trict, about 11
See also Defiance district. (Hubon
miles northeast
02:6, 7; Merrill 14:665-666).
of San Clemente,
near the River-
side County line
American Queen
See Defiance district. (Hubon 02:6).
property
Barona
See Daley mine in text. (Aubury 05:260 08:345; Eric 48:320; Hubon 02:6; Merrill 14:667; Tucker 25:330; Tucker and Reed 39:13-14) .
j
29
Beehive (Copper
North edge sec. 1,
Howard V. Harrison,
Irregular bodies of sheared, chlor-
1 Explored by 10-ft. and 100-ft. adits
King?) pros-
T8S, R6W, SBM
Thomas Dunston,
itized granitic rocks within San-
(latter now caved) . Inactive since
pect
(proj . ) ; near
Paul Harris, Beth
tiago Peak metavolcanic rocks
1932 except for upkeep of access
the San Diego-
Harris French,
contain bornite, chalcopyrite ,
road, and sampling. See also Defianci
Riverside County
Box 502, Fall-
and malachite. Bodies elongated
district. (Engel , Gay, and Rogers
boundary. On
brook (1955)
north-northwestward, parallel to
59:61, 111, pi . 2 ; Hubon 02:6).
the west slope
shear zones of country rocks.
(R.M.S. )
of San Mateo
Largest outcrop 50 ft. by 150 ft.
Canyon, south-
Owner reported that ore contains
west of the
as much as 7 percent copper , 4
junction of
dollars per ton in gold, and
Nickel (Quail)
traces of silver.
and San Mateo
Canyons.
30
Clark prospect
SE*s sec. 1, T8S,
Undetermined (1958)
Shear zones in Santiago Peak meta-
Explored by shallow cuts. Claims
R6W, SBM (proj .);
volcanic rocks contain bodies
located in Defiance district after
Defiance dist-
W. A. Clark (?) ,
which contain copper sulfide and
claims listed by Hubon (1902) invalid'
rict, about 11
Fallbrook (1914)
oxide minerals.
See also Defiance district. (Hubon
miles northeast
02:6, 7; Merrill 14:665-666).
of San Clemente.
Coleman property
See Defiance district. (Hubon 02:6; Merrill 14:665-666) .
Copper Brick
Julian district.
See tabulated list under "Nickel".
deposit
(Merrill 14:667) .
Copper King
See Defiance district. (Hubon 02:6).
property
31
Daley (Barona) mine
Danes Lea
South of Ramona.
See text. (Aubury 05:260; 08:345;
Eric 48:320; Hubon 02:6; Jenkins 48; Merrill 14:667; Tucker 24:370; 25:330; 331; Tucker and Reed 39:13-14, pi . 1 ) .
See Encinitas mine in text . (Aubury 05:259; 08 : i44 ; Eric 48:320).
Defiance dis-
Around mutual
Sparse chalcopyrite, bornite and
Hubon (1902) listed the following prop-'
trict
corner separat-
copper oxide and carbonate miner-
erties, which then comprised the
ing T's 7 and
als in northwest-trending zones
Defiance district: American Queen,
8S, and R's 5
in Santiago Peak metavolcanic
Coleman, Copper King, Delia and
and 6 W, SBM
r ock s .
Fisher. These were grouped in the NE1;, T8S, R6W, SBM (proj.). The
(partly project-
ed) ; along
properties noted by Hubon were not
boundary between
mentioned in subsequent California
Riverside and
Division of Mines publications, how- ]
San Diego
ever, and their exact locations are
counties, about
undetermined . More recent names that '
11 to 12 miles
have been applied to the deposits,
northeast of
which are described elsewhere in this ,
San Clemente.
list, are as follows: Under "Copper"! - Beehive , Silver Shine, American Girl and Clark prospects; under "Iron" - Mammoth deposit. (Hubon 02:6, 7; Merrill 14:665-666; Engel, Gay, and Rogers 59:111, pi . 2) .
Delia property
See Defiance district. (Hubon 02:6).
Descanso
Near Descanso.
Primarily a gold mine, but a smelter
(Magdalcna ,
shipment in 1935 yielded a very small!
Ellis) mine
quantity of copper. (Eric 48:320).
1963]
San Diego— Mineral Resources
71
Copper
Map
Name of c/o/mt
L ocot ion
Owner
Geology
Remarks and references
No
mine, or group
(Name, address)
Eagle mine
Julian district.
A smelter shipment in 1938 yielded 7,000
pounds of copper. This was probably from custom ore milled on the property. The Eagle mine is described in the tabulated list under "Gold". (Eric 48:320; Jenkins 48) .
32
Encinitas (Danes Lea) mine
Fisher property
See text. (Aubury 05:259; 08:344; Eric 48:320; Hubon 02:7; Jenkins 48; Mahrholz, W. W. , unpublished report of Bear Creek Mining Company, 1952, one page; Merrill 14:666; Tucker 25:331; Tucker and Reed 39:14, pl.l).
See Defiance district. (Hubon 02:7).
Friday deposit
Julian district.
A nickel prospect which also contains copper minerals. See text under "Nickel". (Calkins 16b:77; Eric 48: 320; Hubon 02:7; Jenkins 48; Merrill 14:656, 666-667; Tucker 25:330; Tucker and Reed 39:131.
Gold Star
See Barber Mountain mine in tabulated list under "Gold". (Merrill 14:667).
Magdalena
See Descanso mine. (Eric 48:320).
Napoles
Julian district.
See Gilson prospect in tabulated list under "Nickel". (Hubon 02:7).
Old Ironsides
Northeast of
Gossan deposit which contains* nickel ,
prospect
Ramona.
cobalt and copper. See tabulated list under "Nickel".
Owens mine
Julian district.
A smelter shipment in 1904 yielded 104,000 pounds of copper. This was probably from custom ore milled on the property. The Owens mine is described in the text, under "Gold". (Eric 48: 320; Jenkins 48) .
33
Silver Shine
SW% sec. 31 (?) ,
Howard V. Harrison,
Chalcopyrite and secondary copper
Adjacent to Mammoth iron deposit. Pros-
prospect
T7S, R5W, SBM
Thomas Dunston,
minerals in quartz vein in body of
pected by small open cut and short
(proj . ) ; about h
Paul Harris,
sheared diorite within andesite
adit prior to 1932. No ore produced.
mile northeast
Beth Harris French,
(Santiago Peak volcanics) . Vein
Long idle. (Engel, Gay and Rogers
of junction of
Box 502, Fallbroc*
strikes N60°E, dips 88° southeast,
59:111-112, pi. 2). (R.M.S.)
Nickel (Quail)
(1955)
and traceable for several hundred
and San Mateo
feet.
Canyons, along
south edge of
Riverside County.
(Shown by Engel ,
1959, pi. 2, to be
in San Diego
County) .
34
Undetermined
Sec. 32, T12S, R3W, SBM; about 5h miles north of Encinitas, and Ah miles north of Rancho Santa Fe.
Undetermined (1957)
Nearly vertical mineralized shear zone in fine-grained Black Mount- ain metavolcanic rocks. Zone strikes N. 55° W. and is about 5 ft. wide. Iron- and copper- stained rock, highly sericitized, on dump of untimbered and inacess- ible vertical shaft. (estimated depth 200 ft.). Probably no level workings.
Possibly part of Encinitas mine. (R.M.S.)
72
California Division of Mines and Geology
[County Report 3
Cornwall Stone
Map No.
Name of claim, mine, or group
Owner (Name, address!
Geology
Remarks and references
Dehesa Cornwall stone deposit
See McGinty Mountain deposit in text under "Feldspar". (Sampson and Tucker 31:427-428; Tucker 21:375; 25:358; Tucker and Reed 39:pl.l).
chiefly by the Encinitas Copper Company whose presi- dent was W. W. Harland of San Diego. Records show that ore from the deposit yielded about 5,000 pounds of copper in 1905 and 7,000 pounds between 1915 and 1917.
The Encinitas property encloses part of a northwest- trending zone of copper-bearing mineralization which is about one mile long and 10 to 50 feet in width. The zone extends northwestward from the NW. 14 Sec. 4, across the NE.'/4 NE.'/4 Sec. 5 and the SW.'/4 SW.'/4 Sec. 33, and into the SE. yA Sec. 32. It is enclosed in metavol- canic rocks of probable Jurassic or Cretaceous age. The principal workings of the Encinitas property develop a mineralized shear zone, in the SW. % SW.% Sec. 33, which is subordinate to the main zone. The shear zone dips steeply northeast and is three to five feet in width (W. W. Mahrholz, unpublished report of the Bear Creek Mining Company, 1952, 1 p.). The common minerals at the surface of the deposit are limonite and malachite, which fill fractures; adjacent dump material contains py- rite, chalcopyrite, and very sparse galena. The grade of the mineralized zone was not determined during this investigation, but is estimated to be relatively low.
The principal workings are two shafts, about 100 feet apart, on opposite sides of the tributary of Escondido Creek. The main shaft, on the northwest bank, was partly filled with water in 1955. It was reported by Aubury (1905, p. 259) to be 280 feet deep. The shaft on the southeast bank is 100 feet deep, and also was filled with water. Two drift adits above this shaft, about 10 feet apart vertically, extend southeastward into the side of the canyon for about 35 to 40 feet. They are con- nected by a raise. A site near the main shaft once was occupied by a small concentration plant.
CORNWALL STONE
See McGintv Mountain Deposit in the section on "Feldspar."
DIATOMITE
The only reported occurrence of diatomite in San Diego County is "about 40 miles north of San Diego" (Eakle, 1914, p. 69). This was not confirmed by the present writers.
DUMORTIERITE
See section on "Kyanite, Andalusite, Sillimanite, Du- mortierite, and Topaz."
FELDSPAR
San Diego County has been the principal source of feldspar in California, although none of its feldspar de- posits has been worked since about 1946. The total re- ' corded county production of nearly 100,000 tons, valued at about $600,000, was mined mainly during the 1920's and 1930's. Of the total, about 87,000 tons was mined from the Pacific Deposit, near Campo, which was worked from 1921 to 1943 by the American Radiator and Stand- ard Sanitary Corporation and predecessors. The next most productive deposits are the Buckthorn Deposit near Live Oak Springs, and the McGinty Mountain Deposit near Jamacha. The Buckthorn Deposit probably yielded several thousand tons of feldspar and the McGinty Mountain Deposit about 7,000 tons of feldspar-like rock. Production from the following deposits ranges from 25 to several hundred tons: Black Canyon, Hoover, Langer, Marden, Moore, Spanish Bayonet, Stewart, Ward and Williams, and White Rose. These deposits, except the Stewart, are described herein in the accompanying tabu- lated list. The Stewart Deposit is described in the text under "Lithium Compounds."
The commercial feldspar deposits of San Diego County consist, with one exception, of granite pegmatite dikes which are enclosed in the granitic, and associated meta- morphic rocks of the batholith of Southern California. The one exception is the A4cGinty Mountain Deposit, which consists of a silicified aplite dike composed of a mixture of quartz and feldspar, but used commercially similar to feldspar. Aiineable feldspar in the pegmatite deposits consists chiefly of perthite (potash feldspar plus subordinate proportions of soda feldspar) which occurs in the inner zones of the dikes with quartz and small proportions of biotite, muscovite, tourmaline, and gar- net. (The general characteristics of pegmatite deposits are discussed more thoroughly herein in the "Gem Min- erals" section.) To constitute mineable material, feldspar crystals should be at least six inches in diameter and quartz should not constitute more than 25 percent of the rock (Wright, 1957c, p. 195). Iron-bearing minerals such as biotite, tourmaline, and garnet are deleterious and must be removed before final sale of the product. Most dikes in the county that have been mined for feldspar have formed dip slopes or cap-like remnants on ridges. They have ranged in thickness from two feet (White Rose deposit and others) to as much as 80 feet (Pacific De- posit). Their dip and strike-lengths have ranged from a few tens to many hundreds of feet. Only in the larger
1963
San Diego— Mineral Resources
73
MILE Figure 15. Map showing Laguna Junction and vicinity, and location of feldspar- and quartz-bearing pegmatite deposits. (See description under Laguna Junction in tabulated list.)
operations has the quartz been marketed. Most deposits mined have been worked almost wholly by surface methods.
The exposed feldspar-bearing pegmatite bodies of the county occur as swarms or, less commonly, as single de- posits, such as that at the Pacific Mine. In four areas, underlain by swarms of pegmatite dikes gem mining districts have originated. These are the Pala, Mesa Grande, Ramona, and Rincon districts, which are de- scribed herein under "Gem Minerals." In the Pala dis- trict the Stewart Lithium Mine once yielded a small amount of feldspar, and other dikes in this district per- haps contain mineable quantities of the mineral (Jahns and Wright, 1951, p. 47). In the Mesa Grande district, a small amount qf feldspar has been mined from the Black Canyon Deposit, and a small mineable tonnage of the mineral is reported by R. H. Jahns (personal com- munication, 1957) to occur in the Rose Quartz Deposit. The pegmatite bodies of the Ramona district are rather thin dikes which contain chiefly soda feldspar. Deposits in the Rincon district were determined by Hanley (1951, p. 14, 15) to be void of commercial quantities of feld- spar.
Additional feldspar-bearing dike swarms occur in the Jacumba-Boulevard and Warner Springs regions, in the Oriflamme Mountains area, in the Metal Mountain Dis- trict, and in the Laguna Junction area (Fig. 15). The largest number of pegmatite bodies in the county occurs in the Jacumba-Boulevard region (Photo 6), but these (Marden, Moore, and Ward and Williams Deposits) have yielded only small tonnages of feldspar. The peg- matite dikes of the Metal Mountain District include the Buckthorn and Crestline Deposits.
Potash feldspar is no longer mined in the county for several reasons: ( 1 ) The three deposits that have yielded by far the greatest production— the Pacific, Buckthorn, and McGinty Mountain Deposits— contain very little additional feldspar which could be mined by surface methods. The Pacific and Buckthorn Deposits already contain minor underground workings, and additional mining would necessitate extensive underground devel- opment. (2) Most of the smaller deposits that have yielded small quantities of feldspar are not thick enough to be potential sources of sustained supply. (3) During the 1920's and 1930's operators of small deposits could have their crude material ground at the Pacific Mill at Campo, which was operated by Standard Sanitary Cor- poration. This is no longer possible, and in 1957 there was not a market for crude feldspar itself (Wright, 1957c, p. 199). (4) In addition to the above reasons, since the 1930's in California, feldspar has been largely replaced by talc as an ingredient in wall tile (Wright, 1957c, p. 199).
In 1955 between 5,000 and 10,000 tons of feldspar was consumed in California, mainly as an ingredient in pot- tery (from information furnished by Wright, 1957c, p. 199). The major part of this production was mined near Kingman, Arizona, and the remainder in San Ber- nardino County, at a captive deposit operated by Glad- ding, McBean and Company. In 1955 the price of potash feldspar mined near Kingman was $20.75 per short ton, carload lots, ground to 200-mesh.
Buckthorn (Flynf Silica and Spar Company, State Lease) Deposit
Location: SE.'/4 Sec. 16, T. 16 S., R. 6 E, S.B.M.; about six miles north-northwest of Live Oak Springs, in the southwestern part of the In-Ko-Pah Mountains; in the Metal Mountain district. Ownership: California State Lands Commission, 217 W. First Street, Los Angeles (1959).
The Buckthorn deposit was opened in 1926 by the Flynt Silica and Spar Company, of Los Angeles, and worked by that company until 1928 (when its Los An- geles plant burned). The operation was continued in 1929 by the Mineral Milling Company, which mined the deposit intermittently until 1932. The Chamberlain Com- pany (and its successor, Kennedy Minerals Co.) worked the deposit from about 1935 to 1937. It has been in- active since 1937. Total output from the deposit is esti- mated by the writer to be at least 2,500 tons of feldspar, with a lesser tonnage of quartz.
The deposit consists of three pegmatite dikes that cut across the crest and upper slopes of a southwest- trending interfluve which juts out from the long north- trending ridge east of Thing Valley. The dikes range in strike from westward to north-northwestward and dip to the west and west-southwest. The rocks cut by the dikes are chiefly dark-gray quartz-biotite schist and gneiss, with subordinate quartz diorite.
Nearly all of the feldspar and quartz produced from the deposit was obtained from the middle dike (Photo
74
California Division of Mines and Geology
[County Report 3
Photo 29. Principal workings at Buckthorn feldspar deposit; view northwest. Feldspar was mined from glory hole and underground workings in left middleground and transported to surface by adit whose portal is at the right edge of the dump in the lower left corner of the photograph. Surface of a fault approximately follows the shadow on the left side of the glory hole.
29). This is a relatively short, but bulbous body which strikes north-northwestward across the crest of the in- terfluve and dips about 60° west-southwest. The dike is at least 200 feet long and 60 to 75 feet in maximum thick- ness. Where developed, it is compounded in thickness ll/2 to 2 times by a fault which strikes N. 10° W. and dips very steeply west-southwest.
The exposed part of the dike consists of two layers, the lower of which is composed chiefly of coarse-grained quartz with sparse potash feldspar. It is at least 25 feet thick, and for the most part has not been mined. The upper layer, which is at least 35 feet thick, is composed chiefly of a coarse-grained aggregate of potash feldspar, quartz, muscovite and schorl. Maximum length of the schorl crystals is about 2 feet, and most have been partly replaced by muscovite (Photo 30). Within this layer are lenses of nearly pure potash feldspar as much as several feet in length. Most of the feldspar produced was mined from this layer.
The dike was first worked from an open pit which was later connected to underground workings to form a glory hole. The glory hole is crudely funnel-shaped downward, about 30 feet in diameter at the top, and 20 to 30 feet in depth. An adit used as a haulageway ex- tends north-northwestward from a point about 125 feet southeast of the glory hole. Near the end of the adit, drifts extend east and west for about 140 feet in each direction (Sampson and Tucker, 1931, p. 428-429). In the western drift, a stope 35 feet long, 10 feet wide, and 40 feet high, is connected to the floor of the glory hole by a 10-foot raise.
Very little mineable feldspar remains in exposed parts of the main dike. Exploration for additional feldspar should be aimed at extensions of the dike underground,
Photo 30 (below). Northeast wall of glory hole, Buckthorn mine. In middle is feldspar-bearing rock which contains prisms of schorl (black tourmaline) as much as 2 feet long. Rim of pit is underlain chiefly by quartz.
.963]
Photo 31. McGinty Mountain silicified jlaskite aplite deposit. The material for- merly was used in the manufacture of nitrified tile. View is to the south from a soint near the south end of the deposit.
San DrEGo— Mineral Resources
75
below the glory hole. Large masses of quartz, totaling several thousand tons, are exposed around the glory hole. The dumps are composed mainly of quartz fragments.
The most northeasterly of the three dikes is exposed just southeast of the crest of the interfluve about 200 yards northeast of the main dike, described above. The dike is similar in lithology to the main dike, is about 50 feet thick, and several hundred feet long. The workings consist of north-trending adits, 75 and 100 feet long; a trench, 30 feet long; and a circular pit about 20 feet in diameter, which serves as a hub for two nearly north- trending adits 25 feet long. Additional mineable feldspar probably lies beneath the circular pit, within which is a large exposure of quartz.
The third of the dikes crops out less than 100 yards southwest of the main dike. It is of undetermined thick- ness and extent and was explored only by a trench 30 feet long.
McGinty Mountain (Dehesa Cornwall Stone) Deposit *
Location: E.l/2 NE.1/, Sec. 27, T. 16 S., R. 1 E., S.B.M.; about 6% miles east-southeast of El Cajon, on the east edge of the crest of McGinty Mountain. The deposit can be reached on foot from Beaver Hollow via an aban- doned road. Ownership: Undetermined (1957). Ameri- can Encaustic Tiling Company, Los Angeles (1925).
The deposit consists of a silicified alaskite aplite dike which is enclosed in gabbro and is exposed along the east edge of the crest of McGinty Mountain for about 1,000 feet. The dike strikes northward and dips steeply to the west. As the top part of the dike has been mined for al- most its entire length, exposures are rare, but the width of the workings indicates that the dike ranged in width from about 10 to perhaps 15 or 20 feet. Where not weathered, the rock is hard, creamy-white and composed chiefly of quartz and partly sericitized orthoclase, plus
* Prepared partly from data gathered by R. M. Stewart.
very minor proportions of plagioclase and chlorite ( Photo 31). Its texture ranges from very fine- to medium- grained, and veinlets of quartz commonly cut the rock. Tucker (1925, p. 358) quoted the following analysis for a sample of the rock: silica, 77.68%; alumina, 15.97%; lime, 2.80%; iron, 0.13%; manganese, 0.72%,; and alkalies, 2.04%; total, 99.34%.
The rock has been called "duroc" (Boalich and others, 1920, p. 93), "cornish stone" (Dietrich, 1928, p. 95), and "Cornwall stone" (Tucker, 1925, p. 358). Cornwall stone is described by Burgess (1949, p. 346) as "a feldspar- quartz-kaolin product obtained from weathered alaskite- type granite" at Duroc, Cornwall, England. Thus, only weathered parts of the Dehesa Deposit could be cor- rectly termed Cornwall stone, as Boalich and others (1920, p. 63) reported that the material mined was "ex- ceedingly hard."
The deposit was discovered in 1900 and worked as late as the early 1930's but probably most intensely dur- ing the 1920's. The American Encaustic Tiling Company (which was known as the West Coast Tile Company prior to 1920) used this feldspar-bearing rock in the manufacture of a hard, white, vitrified tile known as "Kaospar" (Boalich, 1920, p. 63). The deposit was mined intermittently to meet plant requirements and probably has been inactive since the early 1930's. Production fig- ures are not available, but a total production on the order of 6,500 to 7,000 tons can be inferred from the size of the excavations.
The rock was mined from open cuts and hauled by truck to El Cajon for rail shipment to Los Angeles. The principal working is a shallow, north-trending trench 10 to 25 feet wide, 5 to 15 feet deep, and about 700 feet long, which follows the crest of the ridge upward to the south. From the south end of this trench, and above it 15-20 feet, a second trench extends southward for about 150 feet (Photo 31). In addition, a 50-foot cut
76
California Division of Mines and Geology
[County Report 3
Figure 16. Map showing patented claim that covers the Pacific feldspar deposit, near Campo, San Diego County.
extends to the east from the south end of the main trench, and there is some indication that an adit may have been driven westward, under what is now this cut, to intersect the deposit. The only additional feldspar- bearing rock in this deposit, similar to that mined, lies beneath the floor of the previous workings. Similar dikes are exposed in the area, but those examined contain small proportions of detrimental, iron-bearing dark min- erals.
Pacific Mine (Arthur Clay Spar Number One, Campo, Pacific Sanitary Porcelain Co., Standard Sanitary, Stell)
Location: Mine— center SW.!4 Sec. 25, T. 17 S., R. 4 E., S.B.M.; on the north side of Hauser Canyon, 5 miles northwest of Campo; Mill— near the north edge of the N.'/2 NW.'/4 NE.»/4 Sec. 10, T. 18 S., R. 5 E., S.B.M., about three-quarters of a mile east of Cameron Corners.
Ownership: Torrance Sand and Gravel Products Com- pany, 25701 Crenshaw Boulevard, Torrance, owns one patented claim which covers the mine workings, and eight (?) contiguous, unpatented claims (1959).
In 1918 William Stell located 9 lode claims in the W. l/2 of Section 25, and in 1924 patented one of these claims, the Arthur Clay Spar Number One, which covers most of the deposit (Fig. 16). From 1921 to 1943, the deposit yielded about 87,000 tons of feldspar and was the principal source of this mineral in California. The deposit was operated during this period by the Ameri- can Radiator and Standard Sanitary Corporation under three company names: Pacific Porcelain Ware, 1921 to 1923; Pacific Sanitary Company, 1923 to 1925; and Standard Sanitary Manufacturing Company, 1925 to 1943. Peak production was from 1927 to 1929, when about 32,000 tons was mined. A small tonnage of quartz
also was produced. The Standard Sanitary Company ceased operations in 1943, partly because of increased labor costs, and partly because of a lack of reserves of easily mined feldspar. Since 1943 no attempt has been made to reopen the Pacific Deposit. In the early 1950's. however, the Campo Milling Corporation (first under the direction of T. J. Williams, then F. A. Matthews) produced two types of chicken grit (one of granite, and one of fossil shells) and other products, at the Pacific mill (Photo 32).
The deposit consists of a granite pegmatite dike which nearly forms a dip slope on the northeastern wall of Hauser Canyon (Photo 33, Fig. 17). The dike strikes northwestward and dips about 45° southwest. Its strike- length and dip-slope length are each about 500 feet, and its maximum exposed thickness is about 80 feet (Foote, 1951). Foote described four zones within the body: (1) a border zone, about 5 feet thick, composed mostly of graphic granite; (2) a wall zone, 5 to 20 feet thick, of coarse-grained, quartz-perthite pegmatite (Fig. 17); (3) an intermediate zone 5 to 30 feet thick of blocky perthite; and (4) a quartz core. Two inclusions that contain thor- ium-bearing monazite are related spatially to the core. Biotite is sparse and tourmaline is very sparse through- out the deposit. The body is bordered by granitic and metamorphic rocks and contains elongate inclusions of schist.
Potash feldspar-bearing rock was selectively mined from both the wall zone and the intermediate zone (Wright, 1957c, p. 196), and quartz-bearing rock was obtained from the wall zone and core. The deposit is developed by at least four terraced open cuts and lim- ited underground workings (Fig. 18) which were driven from the upper, or main cut. This cut is about 220 feet high, and 50 to 200 feet wide (Wright, 1957c, p. 196).
Photo 32 (below). Pacific mill, just east of Cameron Corners and adja- cent to San Diego and Arizona Eastern Railroad. Feldspar and quartz from the Pacific mine, about 5 miles to the northwest, were milled here until 1943. The Campo Milling Corporation operated the mill in the early 1950's.
obo»' it I
Itnic
963
San Diego— Mineral Resources
77
Photo 33. Pacific feldspar deposit, bout 5 miles northwest of Campo. It was le principal source of feldspar in Cali- irnia from 1921 to 1943.
Figure 17 (below). Geologic section through pegmatite body at Pacific feldspar mine, San Diego County. After Foofe 1951, in Wright 1957c.
NE
EXPLANATION
<? ^
E
locky Pert!
li te
M
jssive Quar
tz
4-4-4- + 4-4-
-t- 4- -1-
C( Pe
>arse - groir
rthi te - qu
pegma ti t<
ted
artz
|
rrt-r rrrrrr rrrrrrrr rr
Gr
aphic gran
ite
Schist
:S$$$$$^-
£
0
,'rr
■8
+ /r-i-ri
+ 4-
4- 4- -r/rrr + + Ar'n
//
/
/
/ M /
\y + +
/
'<■/,
W+
A
■4
rr
4,1,1
l} / ', A
W
/
w
1 1 / /
/ M
/
ty
1 {J:
/ M
Metamorphic rock - undivided
50
SCALE IN FEET 0
50
SW
78
California Division of Mines and Geology
[County Report
Old Level e I ev 286 2
IS) R o i s e
Figure 18. Plans of underground workings, Pacific mine.
Most of the high quality feldspar that could be mined from the surface has been removed; and a former mine operator stated that very little potash feldspar, that could be easily mined, remains underground. The under- ground workings no longer are open.
Crude feldspar- and quartz-bearing rock was hand- sorted, crushed, and screened to one-inch size at the deposit. Then it was trucked six miles to the company mill on a San Diego and Arizona Eastern Railroad siding
east of Cameron Corners (Photo 32). There the rod was further crushed, screened, refined and bagged. Fina feldspar products were ( 1 ) 200-mesh for the potterv industry, and (2) 100-150 mesh for the enamel wan industry. Quartz products were ( 1 ) 200 mesh for the potterv industry, and (2) 65-100 mesh for the glass in- dustry. Capacity of the mill was 50 tons per day. Forty- nine people were employed during peak production In February 1957 a large part of the plant was intact
1963]
San Diego— Mineral Resources
79
Feldspar
Map
Name of c/o/m,
Location
Owner
Geology
Remarks and references
No
mine, or group
(Name, address)
American Encaus-
See White Butte deposit in text under
tic Tiling
"Quartz and quartzite". (Miller 35:
Company
134; Sampson and Tucker 31:445; Tucker 25:375) .
American Radiatoi
See Pacific mine in text.
and Standard
Sanitary Cor-
poration
Arthur Clay Spar
See Pacific mine in text. (Tucker and
No. 1 claim
Reed 39:pl.l) .
35
Bear deposit
S^NW^ and NW^SW?s
A. Dawson,
A small pegmatite deposit.
Four lode claims located by present
sec. 35, T11S,
P.O. Box 99, Rt.l
owner in 1924. Developed only by
R1W, SBM; 9
Del Mar (1957)
minor, shallow workings. No pro-
miles northeast
duction. Not examined during present
of Escondido, on
investigation.
southeast side
qf Bear Valley.
Benton Ranch
See Laguna Junction deposits.
36
Black Canyon
Nearly cut by line
Undetermined (1957)
A pegmatite body of undetermined
Exposed in face of road cut along east
deposit
between E^NE^
extent exposed in road cut. Con-
side of Black Canyon road. Face of
sec. 19, and W*j
tains abundant potash feldspar,
cut is about 50 ft. long and as high
NW^ sec. 20,
quartz (some of which is smoky).
as 20 ft. During mid-1930 's about 5
T12S, R2E, SBM;
and biotite. Very shattered and
tons of feldspar shipped to Los
about 6 miles
iron-stained.
Angeles by L. B. Spaulding, Ramona.
north- northeast
No further work done. (Tucker and
of Ramona.
Reed 39:54, pl.l) .
37
Buckthorn (Flynt Silica and Spar Company, State Lease) deposit
California China Products Co.
Campo
In-Ko-Pah Mts.
See text. (Sampson and Tucker 31:428- 429, 448; Tucker and Reed 39:34, pl.l).
Probably same as McGinty Mountain
deposit, which see in text. (Merrill 14:687) .
See Pacific mine in text. (Dietrich 28: 201; Miller 35:134; Tucker 40:12; Tucker and Reed 39:34-37, pi . 1 ; Tucker and Sampson 40:12) .
38
Carlsbad deposit
West edge NW^ sec.
Undetermined (19 58)
Two pegmatite dikes were prospected:
Wheeler and associates located 5 claims
26, T9S, R4E,
one strikes northeast, dips 45°
prior to 1930 and prospected deposits
SBM; about 7-3/4
W. F. Wheeler,
west; the other strikes northwest,
for feldspar and mica. No production.
miles northeast
Box 555,
dips east (R. J. Sampson, Calif-
Dike no. 1 developed by cut 80 ft.
of Warner
San Bernardino
ornia Div. of Mines, unpublished
long, 10 ft. wide, and 5 to 15 ft.
Springs, on the
(about 1930)
report, about 1930).
deep; dike no. 2 developed by cut 30
east edge of the
ft. long, 7 ft. wide, and 9 ft. deep.
Lost Valley
Not visited during present investi-
plateau; in
gation.
Anza-Borrego
Desert State
Park.
Clark mine
Rincon district.
Small output of electronic-grade quartz crystals. See tabulated list under "Gem minerals". (Hanley 51:22).
39
Crestline and
Eh sec. 21, T16S,
L. B. Spaulding,
Deposit consists of several pegma-
Two unpatented north- trending claims.
Gem Spar
R6E, SBM; about
P.O. Box 15,
tite dikes which crop out of
Developed only by shallow cuts and
claims
5*5 miles north-
Ramona (1957)
dark-gray quartz-biotite schist
trenches. No production. {Tucker
northwest of
on a south- to southwest-facing
and Reed 39:37, pl.l) .
Live Oak
hill slope. The dikes dip moder-
Springs, in the
ately south to southwest, slight-
southwestern
ly more steeply than the hill
part of the In-
slopes. They range in dip length
Ko-Pah Mts.
from about 50 to 300 ft. and in strike length from 100 to 150 ft. The dikes range in thickness from 2 or 3 to perhaps 6 ft. The core of one dike examined closely is 1 to 2 ft. thick and composed chiefly of quartz with a minor proportion of large feldspar crystals. The outer part of the dike is composed of graphic granite with muscovite.
80
California Division of Mines and Geology
[County Report
F eld spa r
Map No
Nome of claim, mine, or group
Location
Owner (Name, address)
Geology
Remarks and references
Dos Cabezas prospects
Elder deposit
Elliot deposit
Flynt Silica and Spar Company
Hoover (Lakeside, Turner) deposit
Jacumba Copper Co. prospect
Laguna Junction (Benton Ranch) deposits
Sec. 22, T16S, R8E, SBM; one mile north-north west of Dos Cabezas siding; in Anza-Borrego Desert State Park.
Near Campo.
Undetermined (19 59)
George W. Elder, 799 Oak St. , San Francisco (1925)
J. R. Elliott (1939)
SE^NE^ sec. 35, T15S, R1E, SBM; about 5-1/3 miles east- southeast of Lakeside. The deposit can be reached from the Harbison Canyon-La Cresta road.
Sec. 26, T17S, R8E, SBM; about 4 miles north- west of Jacumba
Sec. 36, T15S, R4E, SBM; seel T16S, R4E, SBM; and sec. 6, T16S, R5E, SBM; within one mile north and east of Laguna Junction, as shown on map m text.
Wellington I. Hoo- very. Route 3, Box 363, Lakeside (1955)
J. R. Elliott (1939)
Undetermined (1957)
Quartz-potash feldspar dikes in schist and diorite. Dikes vary widely in thickness and size of crystals.
Remnants of several pegmatite dikes are exposed on a ridge slope which faces southeast toward Harbison Canyon. The principal dike strikes eastward , and dips about 25° to the south. Its exposed portion contains two layers: the uppermost layer is at least 4 ft. thick and is composed chiefly of quartz with a minor proportion of potash feldspar crystals as large as 2 ft. in diameter; feldspar was selectively mined from this layer. The lower layer is about 5 ft. thick and is composed chiefly of glassy quartz, some of which is smoky. Very little additional feldspar, which can be mined easily from the surface, remains in the deposit.
Deposits consist of exposures of pegmatite dikes , several of which can be seen from the two paved highways. The two largest de- posits are described. Dike No. 1 (as shown on map) caps a small hill; this dike strikes N. 5°-15° W. , dips 65° east, is about 100 ft. long, and is about 25-30 ft. thick. Its core, which is 8-10 ft. thick, is composed of quartz; layers adjacent to the quartz core are about 5 ft. thick and are composed of quartz and coarse grained feldspar, with minor proportions of biotite.
Dike No. 2 is composed of nearly pure quartz, with sparse biotite; it is between 100 and 125 ft. long, and is 15 to 25 ft. thick.
See McGinty Mt. deposit in text. (Wright 57c:197) .
Developed by shallow cuts and pits. Probably no production. (Sampson and Tucker 31:428; Tucker 25:359; Tucker and Reed 39:37) .
Reported to have operated from 1920 tc 1929 and yielded about 6200 tons of feldspar. Could not confirm existence of this deposit in 1957. Perhaps same as Buckthorn which see in text. (Wright 50:160; 57c:197).
Incorrectly plotted by Tucker and Reed (1939) in sec. 31, T17S, R8E, SBM. It is in the southwestern part of Imperial County. (Tucker and Reed 39: 54, pl.l) .
See Buckthorn deposit in text, and Tucker 31:428-429).
(Sampson
Principal development is a north-trend- ing trench 50 ft. long, 20 ft. wide, and 10 ft. deep. Sampson and Tucker (1931, p. 429) reported that "a con- siderable tonnage (of feldspar) has been shipped." According to present owner, feldspar was shipped to Ameri- can Encaustic Tiling Company, Los Angeles. Pegmatite deposits to the northwest of the Hoover, in the S^ sec. 26, also have been worked for feldspar, and in the 1950' s were pros pec ted for radioactive minerals (see Fletcher deposit under Uranium and thorium). (Miller 35:134; Sampson and Tucker 31:429, 448; Tucker 21b; 376; 25:359, 375; Tucker and Reed 39:pl.l).
No additional published information. (Tucker and Reed 39:55).
Dike No. 1. is developed by two short trenches. Production negligible. (Everhardt 51:pl.2; Miller 35:134; Sampson and Tucker 31:445; Tucker 25:375) .
See Hoover deposit. (Miller 35:134; Sampson and Tucker 31:429; Tucker 25: 359; Tucker and Reed 39:pl.l).
963]
San Diego— Mineral Resources
81
Feldspar
lap
Name of c/o/m, m/net or group
Owner (Name, address)
Geology
Remarks and references
Langer deposit
Leonard and Leek prospect
Lookout prospect
Marden deposit
McGinty Mountain (Dehesa Corn- wall stone) deposit
Mesa Grande deposit
Mica Gem group
Mica Springs (Mica Springs No. 1) claim
Mica Springs No. 1
Modern prospect
Moore deposit
Mykrantz (San Vicente) deposit
SW^SE*a sec. 26, T11S, R1W, SBM; about 9 miles northeast of Escondido.
'on Escondido- Ramona Highway. .
NW*a sec. 25(?) , T9S, R3E, SBM; south of Chihua- hua Valley.
Probably sees. 25 and 36, T17S, R8E, SBM; north- east of Jacumba.
H. G. Zanke,
Box 823, Rt. 4, Escondido (1957)
Undetermined (1958)
Vincent Graner, Long Beach (1939)
Undetermined (1957)
South- southeast of El Cajon.
Sec. 26(?) , T11S, R1E, SBM; Mesa Grande district
north of Ramona.
Sec. 35, T17S, R8E, SBM; about 3h miles east- northeast of Jacumba.
Sec. 23, T17S, R8E, SBM; about 5 miles north- east of Jacumba
SE% sec. 36, T17S R8E, and NE^s sec. 1, T18S, R8E, SBM; about 5 miles east of Jacumba, adjac- ent to U. S. Highway 80 on the north.
Sec. 3 (?) , T14S, R1E, SBM (proj) south of Ramona
Undetermined (1957)
Walter Horr (1939)
Undetermined (1957)
Armon Moore, Los Angeles (1925)
J. W. Mykrantz, Ramona (1925)
A poorly exposed pegmatite dike which strikes N. 15°E. and dips steeply west. Length at least 150 ft. Thickness reaches at least 25 ft. The dike is composed chiefly of shattered anhedral to subhedral crystals of potash feld- spar and quartz as much as several feet in diameter . Mica and other accessory minerals are very sparse
Patented ranch land. Developed by 30- ft. stoped adit driven along the strike of the dike. Small output in 1928. (Sampson and Tucker 31:429,
448) .
A pegmatite dike 2\ ft. wide (Tucker and Reed, 1939) .
Main deposit consists chiefly of a nearly flat-lying pegmatite dike which crops out in the NE^NW^ sec. 36. It strikes northward, is about 500 ft. in exposed length, and 2 to 50 ft. in outcrop width. Its thickness ranges from 2 to 10 ft. The core of the dike, which has a maximum thickness of 5 ft. , is composed of coarse-grained feldspar and quartz with minor muscovite and sparse garnet. The mica books average about 1 in. to 2 in. in diameter and the average length of the feldspar crystals is 2 ft.
Reported by Sampson and Tucker
(1931) to consist of a pegmatite deposit in granitic rocks which crops out for 1, 000 ft. Working exposed feldspar 3 ft. thick.
Pegmatite bodies that dip about 45° west occur in a northwest-trend- ing zone approximately 1,000 feet long. The pegmatite contains feldspar aggregates and indivi- dual crystals to 3 ft. in diam- eter. Quartz layers are as much as 2 ft. in width. Muscovite and biotite are minor. Red garnets also occur.
A pegmatite deposit.
Could not be located during present investigation. (Sampson and Tucker 31:429) .
Four unpatented claims. Explored by 2 open cuts, 8 ft. and 4 ft. long. (Tucker and Reed 39:37, pl.l).
Probably same area as that in which Tucker (1925) stated 15 claims had been located on an "outcrop of feld- spar and silica that can be traced for a distance of five miles.... Two hundred tons of spar and 50 tons of clear silica had been mined" in 1924 and shipped to Los Angeles. The original locator was Jack Marden of National City and in 1931 the owners were A. W. Smith and E. Carson of San Diego. The main deposit is developed by several shallow cuts and trenches. Sec. 36 now is owned privately and in 1957 most of sec. 25 was covered by part of the Mica Gem group which is described in the text under "Mica" . (Miller 35:134; Sampson and Tucker 31:429; Tucker 25: 359; Tucker and Reed 39:pl.l).
See text. (Boalich 20:63, 93; Dietrich 28:95; Merrill 14:687; Sampson and Tucker 31:427-428; Tucker 21b:375; 25:358; Tucker and Reed 39:pl.l; Wright 57c:197) .
Explored by a 25-ft. adit. No product- ion. Relatively inaccessible. Not inrestigated by present writer. (Sampson and Tucker 31:429).
See Mica Gem group in text under "Mica"
Claim located prior to 1939 by Walter Horr. Later abandoned. Now covered by part of Mica Gem group, which see in text under "Mica". (Tucker and Reed 39:55, pl.l) .
See Mica Springs claim. Reed 39:pl.l) .
(Tucker and
Claim no longer valid. Deposit lies within Anza-Borrego State Park. (Tucker and Reed 39:pl.l).
Deposit was originally covered by a 20-acre lode claim which has been long inactive and is assumed no longer valid. Sec. 36 reportedly is now privately owned. Small output reported for 1928. Developed by 6 shallow pits. (Sampson and Tucker 31:429-430; Tucker 25:359; Tucker and Reed 39:pl.l) .
Patented land. Prospect only. (Sampson and Tucker 31:430, 449; Tucker 25: 359, 376; Tucker and Reed 39:pl.l).
82
California Division of Mines and Geology
[County Report
Feldspar
Map No.
Nome of claim, mine, or group
Owner (Name, address)
Geology
Remarks and references
50a
Imine!
50b [mill
Overlook deposit
Pacific mine (Arthur Clay Spar No. 1, Campo, Pacific Sanitary Porce- lain Co. , Standard Sani- tary, Stell)
Pacific Sanitary Porcelain Company
Pala district
NW^NW>j sec. 27, T17S, R8E, SBM; about 4 miles north-northeast of Jacumba.
Northwest of Campo.
Patten (or Patton) Lode claim
Pearson deposit
Pilz deposit
Powers group
Quality (Orion, Osborne) deposit
San Vicente
Spanish Bayonet deposit
SE^s sec. 23, T9S, R3E, SBM; about 6 miles north of Warner Springs, in south eastern Chihuahua Valley
Sec. 28 (?) , T18S, R3E, SBM; about 4 miles west of Tecate, on the southeastern slope of Tecate Peak, near the summit .
Sees. 19 (?) and 24 (?) , T11S, R2E, SBM; Mesa Grande district, about 2 miles west-northwest of Mesa Grande.
Southwest of
Campo.
Near center w'-, sec. 35, T14S, R3E, SBM (proj.) about 7 miles north- nor thwest of Descanso Junction, and \ mile west of Boulder Creek road.
Undetermined (1957)
Undetermined (1957)
. N Pearson, Aguanga (1939)
Undetermined (1957)
P. W. Pilz, Tecate (1931)
Mary L. Powers, 2858 Monroe, San Diego (about 1955)
P. H. Weber, J. F. Dougherty, and Cecil Lewinson, Alpine (1945)
pegmatite dike which caps a small hillock. Where exposed the dike contains feldspar and quartz crystals which are as much as 2 ft. in diameter. No muscovite is present.
'Many of the larger and more bul- bous dikes in the Pala district contain large masses of perthite with so little biotite or other iron-bearing impurities that the proportion of quartz would be the principal consideration in any selective mining" (Jahns and Wright, 1951 , p. 47) .
Pegmatite dike which strikes north- east, dips southeast, and is about 8 ft. thick. The upper and lower parts of the dike consist of graphic granite which grades inward to a muscovite-quartz- perthite core. The crystals of quartz and perthite in the core are as much as 1 ft. in diameter. Muscovite is sparse.
Deposit consists of a pegmatite dike which contains "spar, which is of good grade. .. (and) .. .easily separated from the silica." (Sampson and Tucker, 1931).
A pegmatite body which dips steeply to the southeast.
See Quality deposit in text. (Tucker and Reed 39:pl. 1) .
See Quality deposit in text. (Tucker and Reed 39:37, pl.l) .
Developed by 2 shallow cuts. Probably no production. (Tucker and Reed 39: pl.l) .
See text. (Burchfiel 36:1-3; Dietrich 28:201; Foote 51; Miller 35:134; Sampson and Tucker 31:430-431, 449; Tucker 21b:376; 25:358, 359-360; 40:12; Tucker and Reed 39:34-37, pi. 1; Wright 57c:196, 197, 198).
See Pacific mine in text. 359-360) .
(Tucker 25:
See also Stewart mine. Wright 51:47) .
(Jahns and
See Powers group. 39:55, pl.l) .
(Tucker and Reed
Probably on patented land. Long idle. No production. Developed by a 30-ft. trench (Tucker and Reed 39:37).
Described incorrectly as in T18S, R2E, SBM by Sampson and Tucker (1931) who reported that holdings consisted of 6 claims. Developed by a 30-ft. trench Not investigated by present writer. Probably no production. (Map location herein is approximate) . (Sampson and Tucker 31 :431) .
A prospect. Property consists of 8 un- patented claims including Patten (or Patton) Lode claim. No additional published information. (Map location herein is approximate) . (Tucker and Reed 39:55, pl.l)
See text. (Sampson and Tucker 31:430, 449; Tucker 25:359, 376; Tucker and Reed 39: 37, pl.l) .
See Mykrantz deposit. (Sampson and Tucker 31:449; Tucker 25:376).
Developed by an open pit that is oval in plan and which strikes northeast; it is about 100 ft. long, 30-40 ft. wide, and 25 ft. deep. Probably several hundred tons of feldspar re- moved in mid-1940 's. Massive quartz is exposed at the bottom of the pit; mineable feldspar remaining is very sparse. (Everhardt 51:114, pi . 3) .
963]
San Diego— Mineral Resources
Fa Id spar
83
Map
Name of claim,
L ocotion
Owner
Geology
Remarks and references
No
mine, or group
(Nome, address)
Spar King deposit
Sec. 13, T9S, R2W,
Orthoclase was reported by Tucker
Reported to have been developed by two
SBM; Pala dis-
and Reed (1939) to have been mined
adits, 20 and 80 ft. long. Location
trict, about 2*s
by H. E. Dougherty, San Diego,
of former operation could not be
miles northwest
from a thin pegmatite dike.
confirmed in 1957. (Tucker and Reed
of Pala.
39:37, pl.l).
Standard Sanitary
See Pacific mine in text. (Sampson and
Manufacturing
Tucker 31:430-431) .
Company, Rich-
mond
State Lease
See Buckthorn deposit in text.
Stell
See Pacific mine in text. (Tucker 21: 376) .
Stewart deposit
Pala district. Notable principally for yield of lepidolite, but some potash feldspar recovered as a byproduct. See also in text under "Lithium compounds". (Jahns and Wright 51:47).
Toms Dream
Sec. 11(?), T16S,
Undeteremined (1957)
Tucker and Reed (1939) reported a
A prospect; explored with shallow open
deposit
R7E, SBM; about
"2 ft. vein of orthoclase feldspar
cuts. A very small deposit probably
8 miles north-
T. J. McCain,
in schist on the east slope of
located near the Crystal Gem beryl-
west of Jacumba.
Boulevard (1939)
Eagle Peak, northwest of Tula (e) Mountain. "
bearing pegmatite in NW^g sec. 11, and not in sec. 15, as placed by Tucker and Reed. (Tucker and Reed 39:37-38,
pl.l) .
Turner
See Hoover deposit. (Tucker 21:376).
Walker deposit
See tabulated list under "Quartz and quartzite. "
56
Ward and Williams
S^NWij sec. 15,
See under "Location'
Deposit consists of a pegmatite
The deposit is developed by a semi-cir-
deposit
T17S, R7E, SBM;
column.
dike that strikes N45°W and dips
cular pit about 40 ft. long which
on leased federal
25° west. It crops out of irregu-
extends about 20 ft. down the dip of
grazing land in
lar but gentle terrain about h
the dike. From the size and shape of
southern part of
mile northeast of the McCain ranch
the workings it is estimated that
McCain Valley,
house. The dike ranges in thick-
between 200 and 300 tons of feldspar
about 2 miles
ness from 15 to 20 ft. The layer
was mined. Sampson and Tucker (1931)
north- northeast
that was mined for feldspar is
stated that a Mr. Ward and a Mr.
of Boulevard.
adjacent to the core and ranges in thickness from 3 to 4 ft.; it is composed principally of feldspar with subordinate quartz and minor biotite and muscovite; maximum length of the feldspar crystals is several ft. The core of the dike is nearly pure quartz and ranges in thickness from 1 to 3 ft.
Williams of Boulevard "shipped several cars of feldspar in 1929" . The material was probably milled at the Standard Sanitary Corporation mill near Campo. Further exploitation of this deposit would necessitate under- ground development, or removal of a large amount of overburden. (Sampson and Tucker 31:431) .
White Butte
See text under "Quartz and quartzite."
deposit
57
White Rose
NE^NE** sec. 17,
Undetermined (1957)
A nearly flat-lying pegmatite dike
The deposit was worked in 1928 by the
deposit
T17S, R5E, SBM;
that ranges in thickness from 2 to
Globe Tile and Porcelain Co., Hynes,
about 6^ miles
7 ft. crops out irregularly for a-
which mined about 150 tons of feld-
north-northwest
bout 150 ft. on the crest of an
spar. No activity since that date.
of Campo and
east-trending ridge. The pegmatite
Developed by 50- and 10-ft. trenches.
about 300 yards
is composed of a medium to coarse-
(Sampson and Tucker 31:431}.
west of the
grained aggregate of potash feld-
Campo-Buckman
spar, minor quartz, and sparse
Springs road.
biotite. The quartz that was removed is stockpiled nearby. About 75 to 100 tons of mineable feldspar are exposed.
84
California Division of Mines and Geology
[County Report
Figure 19. Map showing patented claims on Quality pegmatite deposit, near Campo, San Diego County.
Quality (Orion, Osborne) Deposit
Location: Sec. 21, T. 18 S., R. 5 E., S.B.M.; about VA miles south-southwest of Campo, just north of the inter- national border. Ownership: C. B. and Inez Lind, Box 56, Jamul, own three patented claims (Royal, Quality and Orion) and Michael Auer, 4519 Camellia, North Holly- wood, owns one patented claim (Drummond) (1958).
The Quality Deposit was discovered and developed for feldspar and quartz, prior to 1925, by Robert C. Osborne and Robert S. Stewart. The property consists of four patented, west-northwest-trending, approximately side- by-side claims which enclose about 65 acres in the south part of the middle of Section 21 (Fig. 19). No work has been done on the property in many years, and no pro- duction of feldspar or quartz has been recorded.
The pegmatite dikes that comprise the Quality Deposit crop out on hillocky terrain in a north-trending, crudely elliptical-shaped area about 3,000 feet long and 600 feet in average width. The south edge of the area is nearly contiguous with the international border. The dikes, which are enclosed in partly decomposed tonalite, strike north-northwestward and dip gently. They are several hundred feet in maximum length, but are not well enough exposed to indicate an average thickness. Schorl is very common in dikes in the southern part of the area.
A dike typical of the group ranges in thickness from one to six feet and is composed of a core of quartz which grades abruptly upward and downward into coarse- grained aggregates of pink potash feldspar and minor quartz, and thence into an outer zone of graphic granite.
The dikes have been developed by at least nine shallow pits and cuts, the largest of which is about 50 feet long.
FLUORINE MINERALS
Fluorspar (calcium fluoride) has been reported onl\ from the Mountain Lily Aline, by Merrill (1914, p 705) Francolite (fluorapatite) has been reported to be abun- dant in nodules dredged from the sea floor off Southern • California (Dietz, Emery, and Shepard, 1942, p. 818). J Commercial deposits of these minerals have not been I found in the countv.
GEM MINERALS
The pegmatite deposits of San Diego and Riverside Counties have constituted one of the most important sources of gem minerals in the United States. These de-| posits have yielded tourmaline, spodumene, beryl, topaz, garnet, and quartz crystals with a total value of at least $2,000,000. Mining has centered about two principal mining districts in San Diego County— Pala and Mesa Grande. An estimated 90 percent of the total production came from five mines in these districts, which were most active from 1900 to 1912 (Wright, 1957d, p. 209).
The county also contains nonpegmatite deposits of semiprecious gem or ornamental minerals, but these have been worked mainly by amateur collectors and lapidaries. They include deposits of agate and jasper, axinite, du- mortierite, epidote, garnet, orbicular gabbro, and rhodo- nite.
Gem-Bearing Pegmatite Deposits *
Distribution and General features f
The most productive and most extensively developed of the gem-bearing pegmatite bodies in California are exposed in two areas— at Pala and Mesa Grande— in the north part of San Diego County. The Pala district, which is about three miles south of the boundary between San Diego and Riverside Counties, is 20 miles northwest of the Mesa Grande district. Gem pegmatite areas in San Diego County that are smaller and much less productive than the two noted previously are near Ramona and at Rincon. Individual gem-bearing pegmatite deposits are on Aguanga Mountain, in the Chihuahua Valley area, and near Jacumba.
"Of the gem-quality minerals in these deposits, tourmaline has been mined in by far .the greatest quantity, and gem spodumene has proved abundant in certain of the lithium-rich pegmatites. The mining, which was aimed chiefly at the recovery of these two minerals and the nongem lepidolite [ (see section on "Lithium Compounds" in this report)], also led to the recovery of gem varieties of quartz, beryl, topaz, and garnet.
"All of the gem-bearing pegmatites of San Diego and Riverside Counties lie within the Peninsular Ranges province, a region underlain mainly by plutonic igneous rocks of the Southern Cali- fornia batholith and by prebatholith metamorphic rocks. The pegmatite bodies were emplaced in late Mesozoic time during the end stages of the consolidation of the batholith. Most of them are within the dark-colored, more basic rocks of the batholith, espe- cially in a unit known as the San Marcos gabbro.
* The sections herein on "Gem-bearing Pegmatite Deposits" and "Markets" were extracted almost wholly, and modified partly, from the sections titled (1) "Gem-bearing Pegmatites of San Diego and Riverside Counties" and (2) "Markets," in "Gem stones" by Wright (1957d, p. 208-214) who acknowledges the following sources of information: jahns, 1948; Jahns and Wright, 1951; and Hanley, 1951; and. from R. H. Jahns in personal communication.
t In parts quoted directly, present author's additions are in brackets.
1963.
San Dikco— Mineral Resources
85
"Virtually all of the pegmatite bodies of the Peninsular Ranges province are elongate dikes. Although a given dike is generally rather uniform in thickness, some dikes are only a fraction of an inch thick, whereas parts of others are 100 or more feet thick. The thicknesses of those that contain most of the pegmatite, how- ever, lie within the general range of 4 to 25 feet. Many of the dikes are 1,000 to 4,000 feet long. In some areas the dikes occur in swarms that have filled numerous closely spaced parallel to sub- parallel fractures.
"The percentage of gem material in a given dike bears no obvi- ous relationship to the average thickness of the dike. Indeed the dike at the very productive Himalaya mine at /Mesa Grande aver- ages only about four feet in thickness, whereas much larger dikes have yielded no gem material. Virtually all of the gem spodumene and significant amounts of other gem minerals, however, have been found within bulges in the dikes.
"The dikes are granitic in composition. Large numbers of them iconsist wholly of graphic granite, but others are complex bodies ;of two or more rock units of contrasting texture or mineralogy or both. The gem and lithium minerals have been found in only a small proportion of the complex dikes and in none of the simple 'dikes.
"Graphic granite forms the most of the upper part of the typical complex dike, whereas its lower part contains a fine-grained quartz- feldspar (aplitic) rock. .Much of this fine-grained rock shows a distinct banding, caused by thin layers rich in minute grains of ; garnet or tourmaline, and is commonly known as 'line rock' [ (fig. 20)].
"Discoidal to pod-like masses of very coarse-grained pegmatite occupy the cores of many of the dikes and form the central parts of most of the bulges. Some of these masses consist of quartz- perthite or quartz-spodumene aggregates; others contain only quartz or perthite. In several of the complex dikes this coarse- grained pegmatite has been worked for feldspar or quartz [ (see sections on 'Feldspar' and 'Quartz and Quartzite' in this report)]. Irregularly distributed fracture-fillings and replacement bodies, composed chiefly of quartz, albite, and muscovite, are widespread in the complex dikes.
"All of the gem-quality tourmaline, beryl, topaz, and garnet is contained in a type of pegmatite that is characterized by an abundance of well-formed crystals and lies within or near the cores of the dikes. It ranges from fine-grained to very coarse- grained and consists mostly of quartz, albite, orthoclase, and muscovite. It also contains concentrations of minerals rich in lithium, beryllium, boron, caesium, and other rare elements. This material is popularly known as 'pocket pegmatite" because the crystals commonly are in pockets filled with red clay, but it rarely contains open space and much of it is clay free.
"The gem tourmaline crystals are transparent prisms of the blue, pink, green, and colorless varieties. Nearly all gradations exist between these colors, and individual prisms commonly are bi- colored or multicolored in concentric zones or in layers normal to their long axes. Most of the gem tourmaline occurs in prisms that are pencil-like in size and shape, but individuals as much as four feet long and six inches in diameter have been mined. Tourmaline is the most abundant and widespread gem mineral in the pegmatites of southern California, but a single source— the Himalaya mine in the Mesa Grande district— has yielded consid- erably more tourmaline than all of the other mines combined.
"Spodumene, although locally abundant in the pocket pegmatite, is of gem quality only in the very coarse-grained, quartz-spodu- mene pegmatite. Here it occurs as unaltered residua in the central parts of some of the spodumene laths. The rest of the spodumene has been altered to a milky material composed partly or wholly of clay. In the pegmatites of the Southern California batholith, the gem spodumene is mostly of the pale-pink to deep bluish-lilac variety known as kunzite. A yellowish to colorless variety of spodumene is somewhat less abundant in these pegmatites and a pale-green variety is rare. The transparent spodumene ordinarily occurs in splintery, striated fragments less than 2 inches long, but locally these residual masses are as much as 4 inches wide
A
L J
r -I _ ' L-__r _
Scale in feet
Quartz - spodumene pegmatite, very coarse grained.
. j Massive quartz.
■ ^' Massive quartz with large euhedral crystals I '» ' ' • i of perthite.
Blocky perthite, very coarse grained.
Graphic granite , coarse to very coarse grained.
Line rock : albite - quartz —perthite pegmatite, layered and fine grained.
Figure 20. Idealized sections of pegmatite dikes in Pala district, show- ing typical zonal structure. A, Simply zoned dike, lower part fine grained (Tourmaline King, Tourmaline Queen); B, Bulging dike with more numerous inner zones (Ocean View, El Molino); C, Bulging dike with complex zonal structure (Stewart- Vanderburg-Katerina). After Jahns 1954a.
and 15 inches long. Most of the gem spodumene mined in Cali- fornia has been removed from the Pala Chief, Katerina, and Vandcrburg mines in the Pala district.
"The most highly prized of the beryl gems in southern Cali- fornia pegmatites is a pale rose to peach-colored variety known as morganite. It is associated, in pocket pegmatite, with a nearly colorless to blue beryl. Both varieties occur in well-faced, equant to tabular crystals as much as six inches in maximum dimension. The gem beryl output has been obtained mostly from the Pala Chief, Anita, El Molino, and San Pedro mines in the Pala district, the Victor and Mack deposits in the Rincon district, and the Himalaya, San Diego, and Esmeralda mines in the Mesa Grande district!; and the A.B.C. mine in the Ramona district].
"Transparent quartz, although less prized than the gem min- erals noted above is abundant in many dikes and has been used in the fashioning of cut stones. Colorless to smoky quartz euhedra are abundant in pocket pegmatite, and anhedral masses of rose quartz occur in a few of the dikes. Most of the pocket quartz crystals are smaller than the milky anhedral crystals that are abundant in the cores of the dikes, but locally they are as much as two or three feet long.
"Gem topaz and gem garnet, also constituents of pocket pegma- tite, are rarer than the gem stones noted above. The topaz ranges from colorless through pale green to aquamarine, and occurs in well-developed prisms as much as four inches long. The colored
86
California Division of Mines and Geology
[County Report
topaz is rare and most of the crystals arc less than an inch long. Gem topaz has been recovered most abundantly from the Moun- tain Lily [(Emeralite No. 2)1 mine at Aguanga Mountain and from the Lttle Three and A. B.C. mines near Ramona. The gem garnet, mostly spessartite, ranges in color from golden yellow to cinnamon brown, and occurs as dodecahedrons about an eighth of an inch to three-quarters of an inch in diameter. The Little Three and A.B.C. mines have been the principal sources of gem garnet.
''History of Mining Operations. That the gem stones of San Diego and Riverside Counties were gathered and prized by Indians long before they were discovered by white men is shown by the existence of tourmaline crystals in ancient burials. The first recorded discovery, however, was made by Henry Hamilton in 1872 when he noted tourmaline fragments on the slopes of Thomas Mountain in Riverside County and traced them up-slope to a pegmatite dike that was later developed by the Thomas Mountain mine. Subsequently, other minor occurrences of gem stones were noted in this area.
"The next significant tourmaline discovery became known in 1892. This was at a locality near Pala and now occupied by the Stewart mine. Other discoveries of tourmaline in the Pala district soon followed, but were overshadowed in 1898 when the very rich tourmaline deposits at Mesa Grande were first mined.
"In 1902, Fred M. Sickler, while working the Katerina mine near Pala, encountered gem spodumene, a very rare material whose occurrence here attracted the attention of mineralogists the world over. Most of the gem spodumene recovered at Pala proved to be colored various shades of pink and lilac, and soon after its discovery, was named "kunzite" (Kunz, 1903; and Bas- kerville, 1903 ) a new gem variety that became popularly known as "California's own gem." Kunzite, however, has since been recovered commercially in both Brazil and Madagascar.
"Intensive mining in the Mesa Grande area was confined mostly to the period 1900-10, and in the Pala area mostly to the period 1903-14. As many as 70 mines and prospects were being worked at one time and at least 95 percent of the gem output of San Diego and Riverside Counties was obtained in the 1900-14 inter- val. By a coincidence fortunate to the mine operators, the dis- covery and development of these deposits came at a time of high tourmaline prices which were brought about largely by the popularity of this gem in China. The fall of the Chinese dynasty in 1912, however, caused this market to dwindle to insignificance and the resulting drop in price contributed to the virtual discon- tinuance of profitable gem mining in this region. Moreover, by 1914 most of the readily detected and easily worked gem occur- rences had been well exploited, and the discovery of additional gem-bearing pegmatites at most mines had become, in the opinion of the operators, prohibitively' expensive. Nevertheless, the recov- ery of gem stones from the pegmatites of the Peninsula Ranges province has continued from 1914 to the present, albeit irregu- larly and on a considerably smaller scale than before. Much of this later mining has been the work of persons as much or per- haps more attracted by the romance of gem mining than by pos- sible montetary gain.
"Operations at the Tourmaline King mine near Pala continued into the 1920's, and in this later development the pegmatite dike was thoroughly explored by 1,000 feet or more of underground workings; but only a very small amount of tourmaline was added to its previous production. A small output of byproduct tourmaline and beryl was obtained in the removal of lepidolite from the Stewart mine which was last worked in 1928. The Himalaya mine has been reopened on several occasions since it was shut down in 1914, but with generally poor rewards. The most productive of these later Himalaya operations began in 1952 and was continuing in 1956. Since 1930, sporadic develop- ment in excess of assessment work also has been undertaken at the Katerina, Vanderburg, San Pedro, Fargo, and White Queen mines near Pala, and at the Rose Quartz, Esmeralda, and San Diego mines at Mesa Grande.
"Production and Mine Workings. The production records o most of the mines, unfortunately, are incomplete and are incon sistent with respect to the values placed by the operators on thi various types and grades of gem stones. Moreover, a large bu undetermined proportion of the total output has been removet surreptitiously by miners, both during and after regular working hours and from both active and otherwise inactive mines. An other but much smaller fraction of the total gem output has beer removed by amateur mineral collectors whose search has beer confined almost wholly to mine dumps.
"Approximately 90 percent of an estimated 200,000 to 300,00( pounds of gem and near-gem material recovered from the peg matites of southern California has been obtained from only five mines— the Himalaya and San Diego in the Mesa Grande districi and the Pala Chief, Tourmaline Queen, and Katerina in the Pak district. All but a very small part of the remainder has been re-| moved from 10 other mines— the San Pedro, Tourmaline King, and Vanderburg in the Pala district; the Esmeralda and Mesa Grande in the Mesa Grande district; the A.B.C. and Little Three mine; near Ramona; the Mountain Lily at Aguanga Mountain; and the Anita near Red Mountain and the Fano at Coahuila Mountain [in Riverside County 1. About 35 small and widely scattered, addi- tional mines also have yielded gem material, and two to three times as many deposits have been seriously prospected.
"The development of most of the mines began with the dis- covery of gem crystals in pegmatite outcrops or in the float downslope from them. Some workings were started only on bulges in dikes whose exposures were barren of gem material or nearly so. In their early stages most of the mines consisted of open cuts from which shallow underground workings were developed as the mining advanced. In all but a few of the mines the gem pro- duction was obtained from only a single pocket. In each of the five most productive mines, however, numerous pockets were en- countered.
"The mine workings are typically very irregular and most of them range from a few feet to several hundred feet in total length. They were driven through the pegmatite rock that was believed to hold the most promise for gem production, principally along the upper margin of the "line rock"
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