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PHYSICAL SCIENCES LIBRARY UNIVERSITY OF CALIFORNIA DAVIS, CALIFORNIA 95616
STATE OF CALIFORNIA DEPARTMENT OF NATURAL RESOURCES
GEORGE D. NORDENHOLT, Director
DIVISION OF MINES
Ferry Ruilding, San Francisco
WALTER W. BRADLEY
State Mineralogist
San Francisco]
BULLETIN No. 108
[November, 1934
Mother Lode Gold Belt of California
By CLARENCE A. LOGAN
'""^Z':!'^
4156
CALIFORNIA STATE PRINTING OFFICE
HARRY HAMMOND, STATE PRINTER
SACRAMENTO, 1935
O.CD. LIBRART
TABLE OF CONTENTS
Page
LETTER OF TRANSMITTAL 5
INTRODUCTION 7
Foreword 7
Definition 8
History 8
Acknowledgment __- 12
MINES ____13-190
El Dorado County 13
Introduction 13
Lode Mines 15
Seam Mines 43
Table of Mines and Prospects 48
Amador County 55
Geology 55
Geography, Climate, Water, Timber, Power __ 58
Mines 59
Table of Quartz Mines and Prospects __ 117
Calaveras County 125
Geology __ 125
Geography, Climate, Water, Power, Timber 125
Transportation __ 126
Mines 127
Tuolumne County __ 153
Geology __ 153
Ores 154
Geography, Climate, Water, Timber __ 155
Mines 155
Table of Mines 174
Mariposa County 180
Foreword 180
History — The Fremont Grant 180
Geology — __ 181
Geography, Climate, Water, Power, Timber 182
Mines 183
METALLURGY 191
BIBLIOGRAPHY 214
INDEX 221
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PLATES
Page
I. Geologic Map of Mother Lode Gold Belt In pocket
II. Map of Mother Lode Gold Belt in El Dorado County, showing Min- ing Claims and Areal Geology — __ In pocket
III. Map of Mother Lode Gold Belt in Amador County, showing Min-
ing Claims and Areal Geology — In pocket
IV. Section through Patton Shaft, Keystone Mine, Amador County, look-
ing south __ Facing page 94
V. Longitudinal Section in the plane of the Empire Vein, Plymouth
Mine, Amador County Facing page 110
VI. Map of Mother Lode Gold Belt in Calaveras County, showing Min- ing Claims and Areal Geology In pocket
VII. Claim Map, Angels Camp Section of Mother Lode, Calaveras County
Facing page 144
VIII. Map of Mother Lode Gold Belt in Tuolumne County, showing Mining
Claims and Areal Geology In pocket
IX. Plan and Sections, California General Mining Co., Ltd., Jumper :Mine,
Tuolumne County Facing page 168
X. Map of Mother Lode Gold Belt In Mariposa County, showing Mining
Claims and Areal Geology In pocket
ILLUSTRATIONS
Page
Index map, showing location of Mother Lode __ 10
Hadsell Mill at Beebe Mine, Georgetown 16
Open cut, Beebe Mine, Georgetown 18
Montezuma-Apex Mine, Nashville 32
A view of the Mother Lode in Amador County 56
Argonaut Mine and Mill, near Jackson 64
Headframe, Central Eureka Mine, showing skip runway in form of a bridge truss 76
Headframe, Old Eureka Mine, Sutter Creek 79
Headframe, Kennedy Mine 86
Kraut 6-cell flotation unit in mill of Kennedy Mine, Jackson, Amador County__ — 89 Underground scene, Old Eureka Mine of Central Eureka Mining Co., Amador
County . 100
South face, 8th floor, 1635 ft. on 2300 ft. level, Old Eureka Mine, at Sutter Creek,
Amador County __ 102
Distribution of gold and structural features of tvpical quartz vein enclosed in
slate, Plymouth Mine 108
Generalized geological map of Carson Hill, Calaveras County 124
Open cut or glory hole on Morgan Claim of Carson Hill Co 130
Mill of Carson Hill Gold Mines Co., Inc., at Melones, Calaveras County 132
Open cut on Santa Cruz Claiin of Calaveras Group of Carson Hill Gold Mines,
Inc., looking southerly 136
Mill of Senator Mining Co., at Quartz Mountain, Tuolumne County, Table Moun- tain skyline in background 172
Section across veins in New Pine Tree Tunnel 188
Flow sheet of Amador Metals Reduction Co 194
Flow sheet of Amador Consolidated Mill 196
Flow sheet, Dutch-App Mill, Tuolumne County 198
Flow sheet, Treasure Mill, Amador County 200
Flow sheet, Belmont-Shawmut Mill, Tuolumne County 201
Flow sheet. Central Eureka Mining Co., Amador County 202
Tailing disposal from mill of Central Eureka Mine, Sutter Creek, Amador County 203
Flow sheet, Amador Star Mill, Amador County 204
Flow sheet, Montezuma-Apex Mill, El Dorado County 206
Flow sheet, Carson Hill jMines, Calaveras County 208
Flow sheet, Beebe Mill of Pacific Mining Co., El Dorado County 209
Flow sheet, Kelsey Mining Co., El Dorado County 210
Flow sheet, Senator Mine, Tuolumne County 211
Flow sheet, Pacific Mining Co.'s Pine Tree and Josephine Mill, Mariposa County. 212
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LETTER OF TRANSMITTAL
To His Excellency,
The Honorable Frank F. Merriam, Governor of California.
Sir: I have the honor to herewith transmit Bulletin No. 108 of the Division of Mines, State Department of Natural Resources, on the subject of "Mother Lode Gold Belt of California."
In all of the important placer-gold producing districts of Cali- fornia in the 50 's and 60 's search was early begun to find the so-called ' ' mother ' ' vein or lode as the source from which the gold in the gravels had been derived by Nature's process of erosion. Success rewarded these searches in many places. One of the two most productive dis- tricts came to be known as the ''Mother Lode Gold Belt," extending through the counties of El Dorado, Amador, Calaveras, Tuolumne and Mariposa. It is not a single vein or lode, but a zone or belt up to a mile wide for a distance of 120 miles from northwest to southeast, within which are separate and discontinuous veins of gold-bearing quartz.
This belt has been described and mapped in previous publications by both the California State Mining Bureau and the U. S. Geological Survey ; and so great has been the demand and interest in these reports that none of them are any longer available for distribution and second- hand copies are at a premium. For this reason and to record recent developments the within bulletin is presented, w^hich is the result of some six years of records researching as well as field examinations by Mr. Clarence A. Logan, district mining engineer, in the Sacramento office of the Division of Mines. It is accompanied by geological and claim maps. It is particularly opportune at this time of renewed and expanding economic interest in gold mining in California and the West.
Respectfully submitted.
George D. Nordenholt, Director, State Department of Natural Resources.
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'^^'^CA^.^H.^M^'S-
INTRODUCTION
Foreword
Of the numerous reports published upon the geology and mines of the Mother Lode, none have covered its entire length with sufficient detail. The first official report was that of Dr. John B. Trask, the first State Geologist, published in 1853. Others by the same author fol- lowed in the next three years. They describe a few of the principal mines.
The Second Geological Survey, headed by Professor J. D. Whitney, began work in 1861. His valuable contributions to science were halted in 1874 by refusal of the Legislature to allot more money for the survey, or to even approve printing results of the work of his staff; these books were later printed by Harvard University. From 1867 to 1876 the U. S. Commissioner of Mineral Statistics prepared reports of mine production. In 1880 the State Mining Bureau was established. From that time its reports have given a partial record of the State's mining industry, interrupted and restricted by lack or curtailment of funds and by changes in political policy. Notably, between 1896 and 1914, a period of great activity in the State's gold quartz and drift mining, only one small bulletin on quartz mines, that dealing with the Mother Lode, was published. During the period from 1880 to 1900 the U. S. Geological Survey mapped the principal gold mining regions of California in its geologic folios and covered the geology in some of the annual reports. The field covered was so large, how- ever, that very little detailed treatment of individual mines was given.
Since 1914 the State Mining Bureau (now State Division of Mines) has published a fairly continuous record of the principal mining opera- tions, but as is usual when changing legislatures must be depended on for funds, the appropriations, especially since 1922, have not been adequate to do justice to the industry. At present, everything pub- lished on the Mother Lode except a few of the later county chapters published by the State Division of Mines in Mining in California is out of print, including the recent excellent work by Knopf. The mass of information on the subject is therefore only obtainable piece- meal in the larger libraries; and even after perusing everything avail- able there, the searcher will feel a lack of those details so much sought after by the mining investor looking for new fields.
The present bulletin is intended to supply such details as grade and character of ores, working costs and production figures. Some atten- tion will be given to geologic factors which seem to have had a bearing on vein formation and ore deposition. It seems strange that in spite of the mass of published data on this lode, several of these factors have been ignored. The report will be an exposition of the actual results of mining and such value as it may prove to have will be due to the effort made to give the mining investor, engineer and mine manager those data so essential in forming judgments.
(7)
» INTRODUCTION
Definition
The geologic aspects of the Mother Lode are so varied that only one definition, that based on geologic structure, is generally applicable to the entire lode. This may be stated as follows :
The Mother Lode is a belt of country from a few hundred feet to two miles wide, on the western slope of the Sierra Nevada, where the forces of mountain making, batholithic intrusion and subsequent adjust- ment in a great mountain system have led to extensive folding and faulting, of which the surface traces and shallower aspects follow lines of structurally weak rocks or contacts in most places. These struc- turally weak sections have been especially favorable for deposition of ore which has occurred as a result of repeated movements, and the incursions of mineralizing solutions.
In length, the Mother Lode has been proven by the finding of payable mines for a distance of 120 miles in a direction about parallel to the main axis of the Sierra Nevada, north of northwest. That the same geologic formations conspicuous on the Mother Lode continue on the strike northwest after being interrupted in Placer, Nevada and Yuba counties by outliers of a granitic batholith, has been noted by the present author in Butte and Yuba counties in mine workings where the surface is covered by andesite, but these limited exposures have not so far shown payable orebodies.
The distinguishing characteristics of the Mother Lode are uniform strike, north to northwest; uniform dip east or northeast at a rather steep angle, 50° to 80°, and association with certain rocks of slaty or schistose character, particularly Mariposa clay slate (Jurassic), altered andesites (in part Jurassic) and altered peridotite and serpen- tine all of which have been subjected to great compressive stresses or hydrothermal alteration along the distinct overthrust fault zone which has given access to mineralizing solutions from deep-seated sources (probably granitic batholiths) at the time of the great batholithic invasion of the upper crust when the Sierra Nevada were formed, in Cretaceous time. The term lode is particularly applicable to this vein system as most of the mines show two or three practically parallel veins, often with subordinate spurs, all occurring within generally definite walls, but with no vein traceable as a rule for any great length on the strike. See Plate I (in pocket).
History
According to J. T. Wheeler, who was one of the original locators of the Granite State claim, quartz mining history on the Mother Lode in Amador County began with the location of the Original Amador Company's claims by Thomas Rickey on the north side of Amador Creek, followed by the location of the Spring Hill Mine on the south side of the same stream by two preachers named Herbert and Davidson. The location of the Granite State Company's and Pleasant Ridge Company's claims came next. At that time the size allowed by miners* rules for an individual's claim was 120 feet long by 60 feet wide. These locations were made in 1850 ; gold quartz had been found and worked in Mariposa County in 1849. Mexican arrastres were used for several months to crush selected ore, which, in the case of the Granite State, Wheeler reported as yielding $100 a ton. Several
MOTHER LODE GOLD BELT U
localities claim the honor of having the first stamp mill; in Mariposa County the Mariposa Mine had one in 1849 and in Amador County apparently the first was at the Spring Hill followed closely by an. improved one of 12 stamps at the Granite State, for which the six owners gave a one-half interest in the mine in 1851. Mining had begun also on the lode in other counties in 1850.
In several localities the mining conditions were substantially similar, and the same evolution of mining and milling methods went forward. Mexicans built hundreds of arrastres which were used to crush selected ore, notably at Nashville and at the Union Mine in El Dorado County and at Carson Hill, Calaveras County. The amount of such bonanza ores was limited and the process was too slow and expensive to suit the Americans. With 150,000 white miners in the gold regions in the early 1850 's, it is only natural that the crude stamp-mill known in the southern Appalachians should have been introduced in the different counties of the gold belt from Nevada County southward to Mariposa almost simultaneously. The first crude mills with wooden stems had much greater capacity than arrastres, but were in general failures. With few exceptions the quartz mines went into eclipse after a few years. The exceptions were those which had ores rich enough to pay with then-existing high costs, from $7.50 to $15 a ton.
One well-known engineer has stated his opinion that claims on the lode without ore-shoots outcropping at the surface are not likely to make valuable mines. As a matter of fact, nearly all of the largest and most profitable producers, including the mines at Angels Camp, the Kennedy, Old Eureka, Keystone, Plymouth Consolidated, Raw- hide and Princeton were not profitable until depths of 100 feet or more had been reached, and many of them did not pay enough to keep running until sinking had reached several hundred feet, as in the case of the Utica. This mine and the Kennedy were worked inter- mittently for over 30 years before becoming consistently payable. The kernel of truth in the above-mentioned dictum is that a mine known to have paid well at the surface may be expected to repeat at lower levels ; but the examples quoted are enough to show that no claim should be condemned solely for low surface assays.
The Mother Lode was a challenge to the courage and imagination of the bolder pioneer miners who saw the shallow placers being rap- idly depleted before 1855. After the first set-backs which were shared alike by quartz miners at Grass Valley and on the Mother Lode, these men set about solving the problem of profitably working low- grade ores. The successful history of most of the Mother Lode mines is wrapped up closely with the lives of a few sturdy individuals, hard fighters and not too conscientious with those opposed to them, but generally men of their word. Such men as Alvinza Hayward, Senator Gwin, Colonel Nevills, C. D. Lane and W. F. Detert and their mine foremen and superintendents have left a record for the profitable work- ing of low-grade ores which will tax the capacities of modern mining corporations to even approach. From 1865 to 1900 there were few to oppose the quartz miner and little in the way of embarrassing laws to hamper operation. On the other hand, the Mother Lode remained a pioneer country until 1900 or later. There were no railroads. Water
10
INTRODUCTION
was freely available for power as long as the natural run-off lasted, but provisions for storage were limited or absent so that most mines had to close down from July or August until the first heavy rains, usually in December. They could of course use steam for power if grades of ore warranted, and many did, the last remaining steam hoists having been displaced only about 15 years ago. Wagon roads were abominable and became impassable with the first heavy rain so that it was necessary to lay in during the dry season nearly a year's supply of timber, powder, steel and other necessities. The quartz mines of this lode were the trial ground for many of the new processes, new machines and methods. The stamp-mill was steadily enlarged from a weight of 200 or 250 pounds per stamp to 1250 or 1500 pounds each. Frue and Johnston vanners were introduced about 1870-1875 and remained standard equipment to the almost complete exclusion of other concentrators as late as 1920. Dynamite was first
Index map, showing location of Mother Lode
used in 1868. This and the air drill had a great influence in increas- ing tonnage, lowering gold content of mill-heads and necessitating larger mill capacities. Electric power was first used for mine and mill operation in California in 1890 at the Dalmatia Mine, El Dorado County. Chlorination of sulphides was widely practiced until the introduction of the cyanide process in 1896 ; and a few chlorination plants were worked as late as 1915. Cyanide treatment was not as widely used as might have been expected; there were difficulties in its application to some ores, and the advent of railroads after 1900 and the building of pyritic smelters at San Francisco Bay led to shipment of much concentrate.
The cost of mine labor remained almost stationary on the Mother Lode from about 1870 until the World War— $50 to $60 a month with board in the early days became $2.25 to $3 a shift in later years as mine boarding houses were dispensed with and men moved to hotels in the nearby towns. The earlier miners were Americans for the
MOTHER LODE GOLD BELT 11
most part. Although Chinese miners were used in some drift placer mines and for surface work at quartz mines, they never liked deep quartz mining and did little of it. The Americans had been almost entirely superseded by Austrians, Montenegrins, Italians and other Southern Europeans before 1912. Up to the time of the late war, it was not uncommon to see only five or six Americans in an under- ground crew of 200 or more. The Europeans left during the war and lately the underground crews of some of the larger mines are mostly Mexicans.
Attendant conditions are now favorable for mining. Railways run directly to the lode in several places, and practically every mine is either on a lateral State highway or has a short road connecting with one. Electric power is available within short distances for most of the idle mines; all the active ones use it. Timber is abundant usually within a short truck-haul; some operators use ''Oregon pine" (Douglas fir) for shaft sets. Ample water for milling is available in most sections. The elevation, ranging from 700 feet in southern Tuolumne County to slightly over 1800 feet in El Dorado County and 1932 feet at Mariposa insures fine climatic conditions, with only a little snow at the higher elevations.
As regards size of operations, depths reached and gross and net outputs, the mines of Amador County have been most important. The quartz ores in the Mariposa slates have been the most profitable. Vertical depths of a mile have been reached at the Kennedy and Argonaut, with the workings still in this slate. At some other mines, the ore channels have passed out of the slate at shallow depth into the greenstone or hydrothermally altered schists. 'Schist ore' or 'gray ore' has been found at a depth as great as 4850 feet on the dip but has not been mined to that depth. El Dorado and Mariposa counties have also had their best Mother Lode mines in the Mariposa slate, but depths less than one-half those in Amador have been reached. Present operations in these counties are in few places over 1000 feet deep. In Calaveras and Tuolumne counties the ores are almost entirely 'gray ore' or 'schist ore' though the Gwin Mine in northern Cala- veras is in the typical Mariposa slate. The mines here range from a few hundred to 4000 feet deep, but few have exceeded 3000 feet.
The World War, by increasing material and labor costs, put most of the low-grade mines out of business. Just how serious this was, will be indicated by the comparison of tonnage and value of ores for a few years before and after the war. What may be called this state of suspended animation in quartz mining continued until 1929. In that year, gold production (which for some time had been coming mostly from a few dredging companies and half a dozen of the larger quartz mines) had dropped to only $8,526,703 the lowest for the State since 1848, and not much more than one-third of the 1915 output. A revival of interest in gold mining was manifest in 1930, and substantial improvement was indicated by an increase of nearly a million dollars production that year. This rate of gain was held during 1931 and 1932, in which latter year hand placer operations of 'depression miners' were credited with one-half the increase. The necessarily slower increase from quartz mining, due to the time needed in opening or rehabilitating the mines or increasing operations
12 INTRODUCTION
in those alreadj^ producing, showed in 1933 even before the price of gold was raised, in spite of recessions from other sources. The ten- dency to treat lower grade ore partly offsets the effect of higher gold price, so that added output is not a true index of increased activity.
Acknowledgment
The writer wishes to express appreciation of the courtesies extended by the managers and superintendents of the mines visited during the field work for this report. The other sources of informa- tion drawn upon have been so numerous that it would be difficult to give individual credit by footnote in every case, although the effort has been made to list all pertinent publications in the bibliography. The assistance received from the following men must be particularly mentioned: A. V. Udell, president and Byron Rowe, general super- intendent, Pacific Mining Company; the late James Richards and J. C. Heald, for many years owners and operators of mines in El Dorado County; J. A. Norden, manager, and S. P. Holt, superintend- ent, Montezuma-Apex Mining Company; Wm. J. Loring, Robert J. Duncan, and T. S. O'Brien; E. A. Stent, managing director and Alex Ross, superintendent. Argonaut Mining Company ; Albion S. Howe and James Spiers, former and present manager, respectively. Central Eureka Mining Company: E. S. McCurdy and A. C. Wilson of Utica Mining Company ; 0. A. McCraney, Stanley Arnot and A. D. Stevenot, former Mother Lode mine superintendents; Phil Cox, superintendent. Pine Tree and Josephine Mines, and James Kelly. Miss Helen M. Gaylord and Victor C. Heikes of the U. S. Bureau of Mines gave cordial assistance in obtaining gold production statistics and special thanks are due to that Bureau and to them.
MOTHER LODE GOLD BELT 13
MINES
EL DORADO COUNTY Introduction
While the Mother Lode follows the Mariposa slates through the entire length of this county, there are marked variations in the char- acters of the numerous gold deposits along it. In the southern part of the county as far as the Church Union Mine on the north, the veins occur in the Mariposa slate area and share many features with the mines of Amador County. The slate belt is comparatively narrow and is flanked on the west, and for some distance on the east, by the diabase or amphibolite schist which seems to have had such an impor- tant influence on Amador's mines. Topographically, the lode here occupies a narrow stream valley for four miles where the North Fork of Cosumnes River has forsaken its usual westward course to follow the soft rocks.
Near the Church Union, a granitic intrusive has entered the foot- wall of the slate, which changes its course to northeast and begins to widen. From there north, the gold deposits are found largely in the igneous rocks which have intruded the slates, or in the contacts. These intrusives vary in character through the entire scale of increasing basicity from granitic to ultra-basic dikes which latter have yielded ser- pentine. The variations of these intrusiA^es and the increased width of the Mariposa slate have given to the section a wider distribution and a greater variety of gold deposits than anywhere else on the lode. There are quartz veins in slate and schist, impregnations, dolomitic veins, pocket veins and seam deposits.
^Mariposite and dolomitic rock are seen in mines near Placerville and Kelsey, and bring to mind the mines on the lode in Tuolumne County where serpentine is a wall rock. Beginning north of Placer- ville is a type of deposit called 'seam diggings' where gold occurs in quartz veinlets and seams in the decomposed schist of the greenstone dike series and in places in the slate. The soft, rotten upper portions of these deposits have been worked in many places, between Placerville and the Middle Fork of American River. Beginning near Garden Valley, a dike of amphibolite occupies the center of the Mariposa slate, which from here northward is split into two branches, one running north through Georgetown and Georgia Slide, the other northwest through Green- wood and Spanish Dry Diggings. Mining of the * seam diggings ' by the hydraulic process was carried on most actively near Garden Valley, Greenwood and Georgia Slide.
Mining on the Mother Lode in El Dorado County has nowhere reached such depths as in the counties to the south. The mines that have been worked successfully to the greatest depths have been those in the black Mariposa slate, as the Nashville, Montezuma, Church Union and Springfield. In some other mines where wide deposits were worked by open cut, probably the lowest operating costs for mining
14
EL DORADO COUNTY
and milling with white labor anywhere in California were achieved. Electricity appears to have had its first application here to the opera- tion of mining and milling machinery in California. Many of the deposits in El Dorado County, in common with those of other counties on the lode, have been low-grade, and there has been little done with this type since 1915. But among the mines in the black slate are many which have produced in the past ore comparable in value to that taken from Amador's mines. Conditions unfavorable to gold mining generally in recent years have perhaps been the principal reason why the deeper levels of some of these mines have not been explored. For fifteen years the mines of El Dorado County have remained neglected by mining engineers and the better class of promoters. It can not be denied that a prejudice has grown up, which appears to be unwarranted, against the mines here. To this feeling must be added the fact that records of many companies have been lost or were destroyed in the San Francisco fire, so that tangible proofs of exact conditions underground are usually lacking. As a final unfavorable condition, it must be admitted that improper promotion methods and inadequate financing have hurt some prospects.
The present year is witnessing the reopening of several of these mines and there has been a resumption of prospecting all over the county which has led to the bringing in of a few new producers.
Gold an
d Silver Production o1
El Dorado County, 1880-1933
Year
Gold, value
Silver, value
Year
Gold, value
Silver, value
1880
1881
$389,383 550,000 600,000 530,000 575,000 35,000 619,992 706,871 650,000 427,638 204,583 173,279 198,321 294,610 366,707 700,101 812,289 674,626 501,966 404,497 368,541 292,036 335,031 277,304 474,994 384,735 431,746 319,177
S208 900
1908-.
1909 -- -
342,033
238,284
171,304
133,967
105,565
62,688
133.886
401,288
361,821
24,758
28,352
30,121
13,379
34,109
47,340
30,264
28,207
40,212
91,789
82,254
122,017
57,680
78,019
85,322
182,043
540,939
5,504 1,299
1882
1910
1911
1912
1913
1914
967
1883
1,010
1884
1885
16,000
843 250
1886
1,822 365 500 408 275 359
654
1887-.
1888 .
1915
1916
1917
1918
1919..-
1920
1921
1922
1923 .---
1924
1925
1926
1927
1928
1929
1930
1,353 1,496
1889.
85
1890
1891
1892
722 279 155
1893
1894
1895
1896
1897
1898
1899
1900
1901
1,220 356 448 534 886
4,174
8,414 25,129
5,977 52
301 376 185 153 238 472 383 697 236
1902
250
1903
1931
283
1904
1932
438
1905
2,525 2,690 2,301
1933
1,458
Total value
1906-
1907
$15,766,078
$95,838
The natural conditions and the facilities available favor cheap operation along the lode. A State highway traverses most of it, passing within a short distance of nearly all the mines and good branch roads are found everywhere. Electric power and water are generally available nearby, and lumber and timber are produced in
MOTHER LODE GOLD BELT 15
abundance in the mountains which are within easy trucking distance on the east. Placerville, Diamond Springs and Auburn are shipping points on the Southern Pacific Railroad, from which supplies and machinery can be delivered cheaply to the mines, the first two named places being directly on the Mother Lode. Many experienced American miners make their homes in the district, and the good roads permit driving to and from work, so that in many cases camps do not have to be maintained. Funds available can therefore be devoted almost entirely to actual prospecting, with a minimum of the incidental, pre- paratory and 'dead' work so necessary in remote sections.
Lode Mines
Adams GtUch Mine contains 40.68 acres two miles north of Nash- ville in Sees. 25 and 26, T. 9 N., R. 10 E. It was developed through adits by the former owner, J. C. Heald. Between 1902 and 1911 inclu- sive, small lots of ore were hauled from this place to another mill for crushing. The total yield during that time was $9,482.
The vein is reported to be about four feet wide in Mariposa slate. The adits were 180 and 220 ft. long. Notliing is known to have been done on the property since 1914. In 1931 it was one of several mines leased to J. S. Rex Cole, but no new work has been started on it.
Adjuster Mine is on Martinez Creek a short distance above the Union Mine. A crosscut adit was run years ago 250 ft. to the vein, and short drifts followed the vein less than 100 ft. each way, north and south. Both walls are Mariposa slate ; the vein is reported to average 5 ft. wide, but could not be examined at time of visit, as the adit was in bad shape. There is an old mill of 10 light stamps, formerly operated by steam.
Alpine Mine in Sees. 15 and 16, T. 12 N., R. 10 E., is in the south- erly part of the large amphibolite schist area which separates the Mariposa slate into two belts in northern El Dorado County. It was worked in the late 1860 's through an adit and ore was crushed in an arrastre. By 1888, the Union Consolidated Company had reached a depth of 140 ft. and was running a 10-stamp mill. From then until 1902, the shaft was deepened to 300 ft. The vein was reached by crosscuts at 200-ft. and 300-ft. levels. Production stopped, so far as available records show, in 1902 when an output of $6,800 was reported. Some 10 or 12 years later the shaft was extended to 400 ft. in depth, and drifts were extended south on the vein or parallel to it on the three levels at 200, 300 and 400 ft. From a map, it appears that about 600 ft. in length was explored on the 200-ft. level; about 456 ft. on the 300-ft. level, and 475 ft. on 400-ft. level, with several hundred feet of crosscuts.
In 1933, this mine was taken over by Pacific Mining Company. Their work has been done on the 200-ft. and 300-ft. levels. The main vein, striking northwest and dipping 60° to 65° NE., was found to have been crossed by a series of faults dipping 25° S. According to Byron Rowe, general superintendent, three ore-shoots, each about 100 ft. long horizontally and up to 30 ft. thick have so far been found at these intersections. Former operators, who failed to appreciate the
16
EL DORADO COUNTY
MOTHER LODE GOLD BELT 17
geologic conditions, ran drifts through these ore-shoots but in raising soon passed out of the fiat-lying orebodies. Although the ore-shoots show a length of 100 ft. on the levels because of the flat pitch, the stope length is about 30 ft. The vein has two strands, most of the work being on the footwall section and to the south of the shaft. In 1934 a crew of 16 men w^as producing 75 tons a day. Ore is hauled by truck to the Beebe mill at Georgetow'n. It is white, sugary quartz with only about one-half of one per cent of sulphides. A mining cost of $2.19 a ton was reported early in 1934.
Argonaut Mine had a 10-stamp mill previous to 1890, but had produced principally from pockets. It lay idle thereafter until 1921. when it was made the subject of a questionable promotion called Golden Unit Mining Company. A Gibson mill was installed and a few tons of rock crushed is alleged to have yielded a little gold which was used to promote sale of units. No important new w^ork was done. Later, in 1927, it was again the subject of a promotion, and 60 tons of low-grade rock was milled. In 1928, a small tonnage of rock yielded about $15 a ton.
The workings have been superficial, consisting of an adit 405 feet long giving a depth of 171 feet from the apex at time of last visit. The vein was exposed for a length of 110 feet and the face at the time Avas in amphibolite schist.
Beebe Mine is on a town lot at the north side of Georgetown; other land under agricultural patent, the Woodside, the Eureka and Eureka mill site claims adjoin and all are being operated by Pacific Mining Company, A. V. Udell, president, Crocker Building, San Fran- cisco.
The Beebe was prospected about 1917 by Bulkley Wells to a depth of 250 ft. but remained unworked thereafter until 1931, when Alexander Wise took it over. Beebe Gold Mining Company, a Nevada corporation, was formed and a plant was erected containing two Had- sell mills and eyaniding equipment. Mining had been, goifig on only a .short time when Wise died and the property was shortly after taken over hy the present operators.
The Beebe vein is a silicified and mineralized zone averaging 25 ft. wide but having a maximum width of 50 ft., in amphibolite schist. It appears to be very similar to the 'gray ore' of Amador. On the footwall of the ore zone there is a dike 10 inches to 2 ft. wide. There is reported to be only a commercial hanging wall, gold content gradually decreasing in that direction. The ore shoot was reported to have been opened for 600 ft. in length in June, 1934.
The Eureka vein is producing a somewhat higher average grade of ore than the latter. The Eureka claim was opened in early days and some work was done at intervals until 1908. The deeper shaft was sunk 235 or 240 ft. Levels called 85-ft. and 200-ft. levels were turned, and on the latter short drifts were run north and south. Another old shaft is reported 180 ft. deep. The present operators have extended the Beebe 250-ft. level under the Eureka and have sunk a winze to the 500-ft. level on the Eureka vein, and are drifting back from there to the Beebe vein. Ore had been stoped previously in the
2—4156
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EL DORADO COUNTY
Eureka to 130 ft. in depth but the output from this is not definitely known.
The Woodside claim in Georgetown was a producer of specimen ore in early days. It was opened to ai depth of 210 ft. In 1867 it had
Open cut, Beebe Mine, Georgetown.
Photo by C. A. Logan.
a 5-stamp mill and had produced considerable 'high grade,' one wheelbarrow load of which was said to have yielded $12,000. By 1866 at a depth of 110 ft. the ore was showing so much sulphide that the owner had invented a concentrator made of "a sheet of India- rubber cloth 22 inches wide and about 8 feet long, sewed together at
MOTHER LODE GOLD BELT 19
the ends and stretched over two wooden rollers four inches in diameter and three feet apart." This was mounted with one end three inches higher than the other, was supplied with water through a pipe per- forated with small holes, and dumped the sulphides into a box after passing the upper roller. Perhaps it was the parent of the vanners later used in such numbers. The only essential difference appears to be the lack of a shaking motion.
Considerable water was reported in the Woodside workings and this was giA'en as the main reason for stopping work. Nothing has been done there in late years. The vein is reported to be two to three ft. wide, in slate, and to carry over $3 a ton in free gold, besides an unknown amount in the sulphide.
The Beebe mill, illustrated and described under Metallurgy (post) is of interest. A crew of about 45 men was employed at the Beebe and Eureka mines in June, 1934. and were producing and milling 325 tons a day or 7 tons per man-shift. This high efficiency results in a low mining cost, reported at $1.17 a ton early in 1934. This included overhead and general expense. The Beebe ore is a low grade, high- sulphide ore (see under Metallurgy) and only efficient and economical practice permits working it.
Big Chunk patented claim is one-half mile east of Kelsey on one of the veins in the hanging wall of the Mother Lode. It took its name from a large piece of 'specimen' quartz which contained $28,000 in gold and which was found in placer mining the bed of Big Chunk Eavine, a branch of Texas Ravine. This gold was supposed to have come from the Big Chunk vein at the head of the gulch. This vein has a width of about three feet at the surface and is of bluish quartz. It has been worked to a depth of 100 ft. by a shaft, and has an adit 150 ft. long, both caved. It produced a number of pockets beside the one mentioned.
Big Four joins the Isabel on the east and contains 16 acres in a nearly square piece covered by agricultural patent.
A vein which is 30 inches wide at the collar of the shaft, outcrops in the black IMariposa slate and strikes N. 10° W., dipping 55° E. A shaft has been sunk 96 ft. on the vein, \\ith drifts 50 ft. long in each direction at the 50-ft. level, where an ore-shoot 75 ft. long is claimed. Forty tons of ore was reported to have yielded $10 a ton in free gold, and another lot of 50 tons produced $13 a ton, not including sulphides, regarding the amount and value of which nothing is known.
Big Sandy Mine is at Kelsey and is one claim 300 ft. by 1500 ft., patented. Grey Eagle claim adjoins on the north.
The claims are of historical interest, having been located by James W. Marshall when he moved to Kelsey. He did considerable work, especially on the Grey Eagle where he ran an adit which is still open.
The Big Sandy claim was a producer of low-grade ore for several years but lately has been worked only for pocket gold which has been produced by James Kelly, lessee. Occasionally very beautifully crys- tallized gold specimens are found. They resemble those taken out in Placer County near Forest Hill and at the R^d Ledge i\Iine near Wash- ington, Nevada County.
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EL DORADO COUNTY
The low-grade ore was worked in an open cut 750 ft. long, 25 ft, to 30 ft. deep and 8 ft. to 15 ft. wide. James Kellj^, former superin- tendent, states the ore averaged $1.75 to $2.25 a ton, in free gold and that about $66,000 was produced. A vertical shaft was sunk 340 ft. which cut the footwall vein of the Mother Lode at 240 ft. and again in the bottom, as the vein stands nearly vertical. On the 60-ft. level, a crosscut was run 60 ft. west and drifts were run 50 ft. north and 60 ft. south. On the 120-ft. level, the crosscut is 40 ft. long with drifts 15 ft. north and 80 ft. south. A rich stringer was found and a winze was sunk 40 ft. on it, when it was lost. Aside from this, the ore was low grade. The bottom of the shaft is said to be in ankerite two to three feet wide. On the surface near shaft, the footwall rock is an amphibolite schist dike, and the section across the claim shows in order going east, bands of porphyry (altered, obscure) soapstone and ankerite, talcose schist, vein matter 15 ft. wide composed of stringer leads of quartz and carbonates in altered schist, and Mariposa slate 50 ft. wide. The hanging wall of the vein has not been explored, but on the Harlow claim, 600 ft. east, there is a vein which has been slightly prospected.
The specimen gold lately produced came from surface workings south of the shaft, in seams crossing a thoroughly altered rock evidently a dike.
Black Oak 3Iine in the NE14 of Sec. 34, T. 12 N., R. 10 E., near Garden Valley school, is; one of the small mines which has been paying well during the past year. Previously it had been worked only as a pocket mine and had produced little. Edwin W. and Russell J. Wilson, a partnership, have recently been employing 18 to 20 men and have met with success after only a short period of operation and a moderate investment. It is a good example of how chance figures in mining. Neither partner had previoiLs mining experience, and the property lies in a district peopled largely by pocket-hunters.
The amphibolite schist in which the deposit occurs is the southerly end of the large lens containing the Alpine Mine, which lies two miles north. Here the schist has narrowed to a width of only a few hundred feet. The vein and the schistosity of the schist both strike N. 20° W. and dip steeply northeast, the vein forming small quartz lenses up to 3 ft. wide. At the time of "\dsit late in June, 1934, work was being done at a depth of 55 ft. Here the writer noted that a mud slip or bedding plane in the schist crosses the vein, striking N. 53° W. and dipping 37° NE. This mud slip is only one to three inches thick but it appears to have been the principal agent in localizing the deposition of gold. A length of 50 ft. along the strike of vein had been worked at the time, and the operators reported that the gold had been taken entirely from a depth of about three ft. directh^ under the slip. Still in the zone of surface oxidation, the ore carried mossy concentrations of free gold, at times rich enough for recovery by hand ; some ore rich enough to ship to a smelter, and more of milling grade which was being trucked to the Hart mill near by for crushing. The mill ore varied from 2 to 10 ft. wide, extending into the schist walls on each side of quartz. This claim contains seven acres and the plant is very simple, with a small hoist, shop and compressor.
MOTHER LODE GOLD BELT 21
The same operators have a lease on the Davenport property con- taining 320 acres immediately south. The amphibolite schist traverses this land which contains a deposit similar to that at the Hart Mine (which see, post, under Seam Mines). In previous operations a series of open cuts and a crosscut 280 ft. long had been run. In the crosscut Russell Wilson reports that a width of 30 ft. gives assays high enough to permit mining at present. A width of 5 ft. was stoped 90 ft. long by 40 ft. high and is said to have yielded a fair return. A shaft was being sunk to further prospect the deposit in 1934.
Blue Lead claim joins the Big Four on the south and the Isabel on the east. At an early date, previous to 1867, this claim was opened to a depth of 250 ft. and an unknown amount of drifting was done. A 20-stamp mill was erected and a total outlay of $250,000 was said to have been made. The large dump indicates that the work must have been done entirely in the black Mariposa slate, with a large proportion of waste compared to the amount of ore handled. Although the work- ings yielded some fine specimens, it is said operations did not pay, and work had ceased before 1868.
Chaparral or Golden Queen claim, two miles southwest of Kelsey, was discovered in 1872 by Willets. From then until 1875 the property had a mill and was a small producer of ore reported to have yielded from $7 to $15 a ton. By 1875 the shaft, which had been sunk on the middle vein, was 150 ft. deep. The company then operating the mine was also trying to work the Gopher-Boulder mine but evidently lacked funds to carry on any new development. After taking out such ore as was available, they quit both properties. In 1901, the Golden Queen Mining Company was formed, but apparently did very little work on the mine. The shaft finally reached 200 ft. in depth.
The west vein on this claim has been only slightly prospected. "Where it was mined, the middle vein was reported two to four feet wide. In depth, the footwall is said to be slate and hanging wall diorite ; but workings have been inaccessible for years. It has been estimated that a lower adit 820 ft. long would tap the ore 195 ft. below the bottom of the old shaft. This distance might possibly be shortened because of the southward rake of the ore-shoot.
Church Mine (El Dorado or Church Union) was worked as a quartz mine first in 1886 and was 500 ft. deep in 1887. The ore-shoot was rich but not long, and the period of principal operations was about 13 years. Records of the company, like those of so many others, are said to have been destroyed in the San Francisco fire in 1906.
The principal work and production was from the middle or 'kidney' vein. In July, 1890, the ore is stated to have averaged $8 to $9 a ton in the 10-stamp mill ; in August, $13 ; and in September, better than that, exclusive of sulphides. In 1894, a new 10-stamp mill was built which had a duty of 20 tons in 24 hours. The mine is in the Mariposa clay-slate.
The following notes are from a statement made to the writer by James Richards, who was superintendent of the mine for many years. There are no maps nor other exact details available.
"The main shaft was vertical and was 1200 ft. deep, in the foot- wall below 400-ft. level. There was a poor place in the mine between
22 EL DORADO COUNTY
350 and 500 ft., where the ledge cut out and we had only the gouge, then ore came in again. The vein below this averaged six feet wide, with the rich ore in the middle. The 600-ft. and 1200-ft. levels were run clear to the propertj^ line. The crosscut from shaft to vein on the 1200-ft. level was 670 ft. long and from this level we sank a winze on the vein to the 1400-ft. level. The ore milled dovm. as far as the 1300-ft. level had averaged $17 a ton. At 1300-ft. the gouge came in, five to six feet wide; the ledge became so soft and broken that it could be shoveled. It carried about $4' a ton here. On the 1400-ft. level, we drifted 80 ft. The ground ran and swelled over night so that it could not be held with tight lagging. There was gouge on both walls.
"There was a great d^eal of $2 to $3 rock in the mine that should have been mixed with the rich ore to give a mill feed worth $6 to $7 a ton. ' '
Sulphides formed 1|% to 2^% of ore and assayed up to $140 a ton. The quartz made in lenses or kidneys up to 250 ft. long, but the best ore was said to be a chimney about 75 ft. long. To a depth of 300 ft., the mine made about 20,000 gallons of water in 24 hours, and later made 75,000 gallons daily when opened to 1350 ft.
It is the opinion of the present owner that the orebodies in both the Church mine and the Union or Springfield, were formed at the points where a side vein called the Klondike left the main lode wall and returned to it.
The east vein was worked in the Union (Springfield) mine just south of the Church. From different levels in the Church, prospecting was done on the west vein by running crosscuts during the operations described above. The mine was unwatered in 1900-1901 with the idea of checking up on the reported results of that previous work. There is no information regarding what was found, but work was not con- tinued. The west vein, however, is known to be quite low grade.
Bihliographv : Cal. State Min. Bur. VIII, p. 191; X, p. 171; XII, p. 106 ; XIII, p. 137.
Cincinnati Mine, four miles north of Kelsej^, covers a stringer lead deposit in a decomposed dike in the INIariposa slate ; it is not certain that the open cut from which the last rock was milled previous to time of visit in March, 1932, had reached the hanging w^all, though a width of 10 feet had been cut. Older open cuts and shallow shafts extend south along the vein probably 600 ft. to the propertj^ line.
No record remains of the results of earlier work. In 1917 the claim was equipped with a light 5-stamp mill and the first clean-up early in 1918 is reported to have given an average return of $3.82 a ton by amalgamation alone. Later tests have given better results but no recent production has been reported.
Coe Hill Mine {Gold Star or Bathurst) is a mile south of Garden Valley. Shallow shafts have been sunk on several veins. Late in 1921, A. Tetrault and associates milled 50 tons from a dump and from an adit, which is reported to have plated $7 a ton. In 1925, Ed Bathurst, the owner, reported production of some $6 ore, and the next year a smaller lot of much higher grade, containing over an ounce of gold per ton. Since then, there has been no record of production.
MOTHER LODE GOLD BELT 23
A small 2-stainp mill was formerly operated. This property adjoins the Oro Fino.
Crown Point and Gold Queeyi Consolidated. These two patented claims cover 3000 ft. in length and 600 ft. in width along the Mariposa slate 2^ miles from Diamond Springs.
The Crown Point has a shaft 500 ft. deep which is intersected at a depth of 300 ft. by a drain tunnel 600 ft. long. The 400-ft. level was run 250 ft. along the east vein of the Mother Lode. This vein was 8 to 20 ft. wide. A crosscut was run from this level westward through the schist for 60 ft. to the west vein, which showed a thickness of 7 ft. ; it was followed 50 ft. by drifting. Mill tests of quartz from both these veins are reported to have been satisfactory; but there is no written record of them available.
Another shaft was sunk 150 ft. south of the first, to a depth of 150 ft. Here the ore was reported in small lenses. Several small lots are said to have jdelded $20 a ton or more. All of this work was done near the north end of the propert3^ About 1000 ft. south some shallow shafts, tunnels and trenches have been run in search of pockets.
Dalmatia Mine, east of Kelsey on the hanging-wall side of the Mother Lode, has the distinction of being the first mine in California to employ electric power for the operation of mining and milling machinery. Hydroelectric power generated on Rock Creek was sent to the mine over a line one mile long and was first used in February, 1890, to run Huntington mills and other equipment.
The property before that had been known as the Kelly mine and a shaft had been sunk 260 ft. upon a vein two feet wide, crossing the main seam belt lode at an acute angle and producing ore which is said to have yielded $16 a ton. After the sale of the mine to an English company the preparations for working the low-grade orebody began with the driving of an adit 1200 ft. long to furnish an outlet for ore to be mined in a glory-hole above. AVhile this adit was being run, a flat or 'blanket' seam was struck from which $14,000 in pocket gold was taken in two days. The main low-grade orebody was later mined by open pit, dropping ore through raises to the adit level, and crushing in Huntington mills.
Two miners working on contract mined the ore at a cost of only 7^ cents a ton as it was soft and very easily broken. It is believed that the cost of mining and milling here, which is claimed to have been only 43 cents to 56 cents a ton, set a low record that has not been sur- passed in California. These operations extended from 1890 to 1894. An open cut about 500 ft. long averaging about 40 ft. wide and 80 ft. or more in depth was made. The gold occurred free in the seams and quartz stringers in the rotten amphibolite schist characteristic of the seam belt.
Esperanza (Garden Valley) Claim is one mile northwest of Garden Valley on a narrow dike of amphibolite schist altered from igneous rock that intruded the Mariposa slate or was contemporaneous with it. In 1890 the claim was being developed and was supposed to have a deposit of low-grade ore. A 20-stamp mill was erected and a sale made later to an English company. In 1898, after the shaft had been sunk
24 EL DORADO COUNTY
600 ft. vertically and 700 ft. of drifts had been run, this company crushed about 1000 tons of rock. Thereafter, they quit work and sold the machinery in 1900.
Falls Mine. Jos. Drechsler, owner. It is in the NE^ of Sec. 1, T. 9 N., R. 10 E., mineral survey 5815. An adit has been run 235 ft. and the OM^ner has been sluicing the surface to find the vein from which gold has come.
Golden Gate (McNulty or Oakland) Mine. This comprises two patented quartz claims and 40 acres of patented placer ground. It is reached from El Dorado and lies just south of the Springfield mine.
This was one of the older mines, having been located about 1852 by W. J. McNulty and having been worked before that by Spaniards and Mexicans using arrastres. It was formerly known as the McNulty. On the claim of that name a tunnel was run about 300 ft. to the vein giving backs of 200 ft. on the middle vein, and having been continued from there as a crosscut for 300 ft. farther in the direction of the east vein, which here shows immense outcrops on the surface. The tunnel was never completed as far as the east vein and it would be necessary to run it about 200 ft. farther to reach that vein. It is estimated that if this were done there would be about 500 ft. of backs above the tunnel on the east vein. Where this tunnel struck the middle vein an internal shaft was started and was sunk to a depth of 600 ft. Most of the ore was stoped out from this shaft below the tunnel for a length of about 300 ft. According to James Richards, who was formerly engineer of the property, this ore averaged $15 a ton in a 10-stamp mill then located on the mine. This vein had an average thickness of ^ ft.
On the St. Louis mine, which lies east of the McNulty, the only work done has been three or four small shafts which show the east vein to have a width of from 8 to 12 ft. with assay values reported to run from $4 to $8 a ton. This was the vein toward which the tunnel from the McNulty was run.
Goplier-Boulder Mine is a mile and a half north-northwest of Kelsey and covered 3611 ft. in length along the lode as originally surveyed.
The Gopher mine proper w^as worked in 1858 when it produced $15,600 but the mill was removed before 1868. Ore was mined in two open pits and dropped through raises to a lower adit. Ore averaged $2.50 a ton and made in flat quartz stringers making into the main lode with a low dip to east. The open pits were 40 ft. wide. The upper tunnel followed a vein four feet wide for about 200 ft. This also was worked at an early date for a length of 120 ft. and 100 feet high and is supposed to have been rich, as pillars assayed $16 a ton. A lower tunnel 850 ft. long has a drift 150 ft. northwest on a vein four to five feet wide which has been stoped in places. A drift northwest struck and followed a flat vein of 'ribbon quartz' for 100 ft. It assayed $2 a ton for 50 ft. and $3.50 a ton for 50 ft.
A transverse gully crossing the line of the lode between the Gopher and Boulder workings indicates a fault, and this is confirmed by the relative positions of the workings which are on the hanging- wall side in the Gopher and on the footwall in the Boulder. The Gopher vein strikes N. 23° W. and the Boulder N. 11° W.
MOTHER LODE GOLD BELT 25
The Boulder vein is a large 'bull quartz' outcrop, 50 ft. wide at the Boulder shaft and in green amphibolite schist, showing mariposite. The shaft is an incline on an angle of 35°, 260 feet deep starting in the hanging wall, but the best pay was found near the footwall. Levels were run at 50-ft. intervals but no stopiug was done below the 100-ft. level. The ore shoot was followed 130 ft. north and 120 ft. south from the shaft and was mined 7 ft. wide. Old records indicate it paid $6 a ton in free gold and show a production of $40,000 from it. On the 200-ft. level the ore shoot was lost, but 43 ft. north of the shaft ore assayed $3.10 and was followed 42 ft. and is said to have improved up to the face. In the 250-ft. level north the ledge was cut 35 ft. from the shaft on the footwall and is said to assay $3.30 a ton for a width of 7 ft. On the south in the 200-ft. level the ledge was cut but not followed, and on the 250-ft. level it appeared that the ore was pitching north.
Most of the work was done on the property before 1900, and ore was cheaply mined, and milled with 20 stamps and two Huntington mills. The company also operated the Dalmatia (which see) and was the first user of electric power to run mine machinery in the State.
In April, 1931, F. "W. Grosjean had an option on the property and did some prospecting work on the surface, milling some low-grade schist in an old Huntington mill. Only the fine decomposed material was worked. The venture was short-lived.
Griffith Consolidated includes the Griffith and Bryant which is 2999 ft. long and 600 ft. wide and several other unpatented quartz claims giving the total length of about 4500 ft. along the course of the Mother Lode. The claims are a half mile southeast of Diamond Springs.
Most of the work has been done upon the Griffith and Bryant which formerly consisted of two claims. At the time of the original discovery a small shoot of very rich ore was taken from near the surface of the Bryant claim. This ground was worked in a small way for quite a long period during which time several shallow shafts and tunnels were run. The work begun by Griffith and Bryant in the fifties had been carried down to a depth of only 150 ft. when the Jumper Syndi- cate took the property about 1896. They sank the Griffith shaft to a depth of 700 ft. At the 350-ft. level the vein was 5 ft. wide and is said to have milled $8 a ton. The company was no doubt too hasty in putting a mill and other expensive equipment on the property before it had been well prospected. After fully equipping the claims and putting in electric power they continued sinking. At 500 ft. the vein was 12 ft. wide and was running with the schistosity of the slate. Under such conditions it was difficult to obtain clean ore and the ore taken out at that level was said to go $4.50 a ton or less on account of the large amount of wall rock jarred do^\Ti by the heavy drills and blasts. The ore there contained about 3% of sulphides which assayed $36 a ton in gold. On the 350- and 500-ft. levels the work was done mostly north of the shaft prospecting a length of nearly 500 ft. along the vein.
The shaft was continued to the 700-ft. level and on that level on the north end it is stated that conditions began to improve as the vein began to cut at a slight angle across the schistosity of the slate and the walls hardened. When the 700-ft. level was reached an order was given
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EL DORADO COUNTY
by the company to mine 2000 tons of ore and mill tests of this ore, according to the former superintendent, went $4.25 on the plates and 3% sulphides worth $42 a ton. The company closed the mine shortly thereafter and nothing has been done in those workings since.
About 1000 ft. north of this shaft the Klondike shaft has been sunk 150 ft. It is tapped at a depth of 100 ft. by the Klondike tunnel which is 300 ft. long and ^vhich follows the vein. The vein here shows in the form of small lenses from one foot to four feet in thickness. Two or three lots of ore from these workings milled from $20 to $65 a ton. A lot of about 100 tons taken out in 1903 is reported to have yielded $32 a ton, but there is no written record of this.
About 1200 ft. south of the Grifath shaft, No. 2 shaft was sunk 253 ft. In the bottom of this shaft it is said that the rock still assays well but is broken into stringers and frozen to the walls.
Harmon Group includes the Van Hooker, Young Harmon, Old Harmon, Gross No. 1 and No. 2 and Eureka patented claims on the Mother Lode just north of Placerville.
The work at time of visit was mostly on the Van Hooker claim, where an old adit was reopened and extended, having a total length of 1200 ft. from portal to north face at time of visit, and giving a vertical depth of 200 ft. on the vein. The ore occurs as a stringer lead and lenses of quartz in Mariposa clay slate, both having been greatly crushed by movement along the course of the vein, which has a wadth of from 2 to 12 ft. A pay shoot 50 ft. long had been stoped and raised upon to a height of 80 ft. and for an average thickness of 5 ft., at time of visit. The best ore shows pyrite, galena and coarse free gold. The ore that had been milled up to that time had yielded $7.25 to $27 a ton. Production began in 1928, and continued for three years.
Further prospecting has since been done on the north, where the adit level was turned to follow the vein, but new orebodies had not been found at time of last visit. A winze was also being sunk from adit level late in 1931.
There is a mill of 10 light stamps and one concentrator, capacity 24 tons daily. Electric power is used to run the mill and air com- pressor.
At the Old Harmon, a new collar was put on the shaft, which was 560 ft. deep in ,1931, preparatory to reopening it to 115 ft., where a prospect was claimed. The mine produced considerable gold (some estimates being as high as $250,000) during early operations. It was worked between 1870 and 1890, ha^^ng been a part of the True Consolidated Mining and Milling Company's holdings, which were developed by a long adit in 1887 and 1888, running the length of the Harmon claims. About 1895 these claims passed into the hands of Placerville Gold Mining Company and little has been done on them since. Nothing was done in 1931 below the surface.
The vein running through the Old Harmon and Young Harmon claims averages 15 ft. wide and in places is 45 ft. to 70 ft. wide, occurring as stringers in slate.
BihliograpMj : Calif. St. Min. Bur. R. VIII, pp. 180-191; XII, p. 125.
MOTHER LODE GOLD BELT 27
Havilah (Nashville) Mine, at Nashville is said by early authors to have been the first quartz mine worked in California; but else- where^ it is stated that it was the first one worked in El Dorado County (1851), and is credited with an output of $150,000 from sur- face and shallow ore, first worked in arrastres. ''The first systematic work" was done in 1868 and the same authority states that "in three vears the mine paid for all of its development work, and plant costing $100,000 and paid $50,000 dividends" from ore yielding $3 to $15 a ton. Litigation closed it in 1871 ; Joshua Hendy obtained a patent in 1880 and by 1882 had sunk the shaft to a depth of 642 ft., the ore from the last 100 ft. of shaft being reported as yielding an average of $8.50 a ton. After producing $45,500 the Hendy interests quit. The mine then lay idle until 1894, when a 20-stamp mill Avas erected and during 1895 and ,1896, G. E. Williams and Hendj^ pro- duced $20,000 from ore mined between the 500-ft. and 600-ft. levels.
No further work was done until 1903. Between then and August, 1906, the shaft was sunk to the 1200 ft. level with drifts 500 ft. south and 1285 ft. north from the shaft crosscut on that level. The north drift explored the vein under the Montezuma IMine, where a short ore-shoot was found. At that time it was equipped with a good plant including a 20-stamp mill. The only production figures at hand for this period were for 1904, when the shaft was 1000 ft. deep, and when 4000 tons yielded $15,325. If there was production in 1905 and 1906, the separate figures for this mine are not available as it was being operated jointly with the Montezuma, and the later work through the Havilah shaft was in the Montezuma. Although the mine was under option in 19,13-1914 with the Montezuma, no further work was done until the present year, except the milling of part of the dump, which yielded $2 a ton or more. At present, the property is being reopened by Montezuma-Apex Mining Company, who are also operating the Montezuma Mine, adjoining on the north. The Havilah shaft has been reopened and during the past . summer the milling of ore from the upper levels was started.
Geologically, the Havilah is similar to the Montezuma, with the same vein in black Mariposa slate walls. The maximum width of vein is 20 ft. but it averages about 5 ft. wide, and in the new work on the 200-ft. level was being mined 6 ft. M'ide in June, 1934. The former operators had stoped for a length of 100 ft. there on the south side of the shaft. The present company was carr^dng on stoping there in June for an additional length of 80 ft.
Hines-Gilhert Mine is 20 miles from Auburn via Spanish Dry Diggings, the last mile being steep trail. The five claims lie partly in El Dorado and partly in Placer County in the steep canyon of Middle Fork of American River, but recent, work has been in El Dorado County.
Two veins occur between Mariposa slate and amphibolite schist, where the slate belt is split by intrusives or interlayered extrusives. The slate bodies here are comparatively small. The hanging-wall vein has been traced about 400 feet on the surface. It strikes N. 20° W. and dips 80° NE. The development work on it consists of short adits and
^California Mines and Minerals: Cal. Miners' Assoc, 1899, p. 310.
28 EL DORADO COUNTY
open-cuts, mostly superficial. This vein averages five to six feet wide and the unoxidized ore is reported to assay well. A crosscut was run to the footwall vein from near the river level, but this had caved and was inaccessible at time of visit. The veins are about 200 ft. apart.
By 1924, one adit had been driven 450 ft. giving a depth of 110 ft., and small tonnages of good-grade ore were produced annually from 1921 to 1924 inclusive. In 1925, ore was low grade, but in 1928 improved again. Since then there has been no production. The output since 1921, less than 2000 tons in all, has varied from $3 to $40 a ton recovered.
The property has a 10-stamp mill, a 3-drill compressor, etc., operated by water power, using water from Canyon Creek, under 600 ft. fall. Work was resumed in 1934.
Ida Livingstone patented claim one mile north of Kelsey has a vein striking N. 50° E. and dipping 80° east at the main shaft, between hard slate walls. For a distance of about 400 ft. on the north end, the vein outcrops as a solid body of white quartz reaching a width of 25 ft. or more, and with little sign of mineralization. An old shaft on the north is of unknown depth, probably less than 100 ft. The south or main shaft was 150 ft. deep, in the creek where water caused trouble. An ore shoot 50 ft. long on top tapered to a length of 10 ft. and thickness of only six inches at the bottom. It paid $26 a ton in a custom mill.
Isabel claim in the Garden Valley district, is traversed by a vein striking N. 30° W. to N. 45° W. and from 2 ft. to 8 ft. or more in width. The vein w^as worked to only a few feet in depth for a length of several hundred feet, and rock was crushed in arrastres at first and later in the mill on the Blue Lead, adjoining (which see). Reported value of ore, $3 a ton on north end on hanging wall side. The vein is in black slate in the shaft which was probably not over 30 ft. deep and was the deepest working on the claim.
Joseph Skinner (Fisk) Mine adjoins the Lemon claim on the south. It is one of several small claims known as seam mines and pocket pro- ducers, and is on the east or hanging wall side of the main lode. The dip of formations here is nearly vertical and steeply west, probably due to hillside drag. In earlier days the surface was hydraulicked. Later workings are reached through a cross-cut 90 feet deep at the face, and running west 232 feet, from which drifting had progressed 76 feet north when visited. On the west of vein, a crosscut shows ankerite to be at least 60 feet thick. Strips of altered gray dike-rock alternate with the black Mariposa slate across the north face. On the east side of fissure a dike 18 inches wide is succeeded by 6 inches of slate full of pyrite ; the latter is followed by 11 inches of dike rock. Gold was observed to occur in a quartz seam in the dike where the quartz comes in contact with the lower (east) side of the slate. Three men were taking out a little specimen ore when visited in 1932.
The Skinner and Lemon claims together M^ere credited with a production of $80,000 before 1897 from a length of 1700 feet. In a few months in 1897 and 1898 a further output of $10,000 was reported from the claims, then known as the Empress Josephine Mine. Again, in the period 1901-1903, nearlj^ $9,000 was produced. Most of the yield was from specimen ore, though some small lots were milled.
MOTHER LODE GOLD BELT 29
Kelly Mine. Miss Margaret Kelly, owner. This prospect is on the hanging wall side of the Mother Lode, on the Kelly Ranch one- half mile north of Kelsey. It is in the Mariposa slate. A heavy vein of quartz outcrops here.
Thirty years ago shallow shafts were sunk, probably in search of pockets, but no ore was milled. In 1932, one shaft was cleaned out and extended and another was sunk, both having depths of 50 ft. at time of visit. They are 150 ft. apart, and both on the vein. In the north shaft, vein is over 6 ft. wide, striking nearly due north while the schistosity of slate strikes N. 15° W. In short drifts from the bottom of south shaft, the vein increased from a width of six inches on the north to four feet on the south in a distance of 33 ft. A flat seam of quartz 10 inches wide enters here from the w^st, and may be connected with the formation of ore. After favorable assays were had, a small mill run was made, but results were vitiated by a mill accident, and work has since been suspended. The gold is very fine, but the prospect ;!ppears to have some promise.
Kelsey Gold and Silver Mine is six miles north of Placerville and was propected many years ago. Kelsey Mining Company, Incorpo- rated, w^as formed in 1926 to reopen it. An old adit was cleared and has since been extended, having a length at present of ,1700 feet, fol- lowing the vein north to N. 32° W. Several footwall crosscuts have also been run.
The claims, which extend for nearly a mile along the contact of narrow dikes of amphibolite schist and serpentine with the enclosing Mariposa slates, show the characteristic ankerite and grey schist ores which appear everywhere on the Mother Lode w^here these formations occur. A cross section of formations from west to east, shows a schist footwall, six inches of mixed carbonates, 8 ft. of grey schist mineral- ized with quartz, pyrite and galena, forming low-grade ore in places ; then 6 ft. of slate 'ribbon rock,' containing much pyrite and some galena ; and the black Mariposa slate hanging-wall. AVithin this lode zone, the formations have been much disturbed by faulting. Another section exposed by crosscuts shows a total width of 46 ft. with the footwall and hanging wall veins as mentioned above.
The company put up a second-hand 10-stamp mill with two Wilfley tablegi in 1928. Some oxidized 'gray ore' from the ankerite zone near the adit portal yielded coarse free gold but this was in only small amount. Beginning about 800 ft. from the adit portal, stoping was carried on at intervals for a length of 320 ft. and to a height of 30 to 50 ft. above the adit. In the four years from 1928 to 1931, inclu- sive, about 15,000 tons was crushed and yielded average returns from $1.80 to $6.40 a ton. This was mostly from the footwall vein. During the next two years, little work was done.
Early in 1934, C. T. Palladine became superintendent and activity was resumed. In June, 20 men were employed. Numerous surface improvements were made, including changes and additions in the milling plant, which was altered to handle ore by flotation, retaining the stamps for intermediate crushing. The flow sheet as it stood June 28, 1934, is illiLstrated under Metallurgy, post. Milling had not been started at that time.
30 EL DORADO COUNTY
Larkin Mine, one mile east of Diamond Springs had been opened to a depth of 250 ft. by 1896 and had three levels. It was a producer until 1903, first having 5 stamps and later 10. The shaft was sunk 800 ft. vertically. The footwall is schist; the vein worked is in the hanging wall of a wide ankerite vein or zone, similar to those so com- mon in El Dorado and Tuolumne counties. The vein and accompany- ing altered igneous rocks are in the Mariposa slate east of the great intrusion of granitic rocks which here has displaced the slates so that the veins strike north or northeast. The principal productive vein was from 4 to 12 ft. wide, contained 11% of concentrate and the meager figures available indicate a yield of $5 a ton in the later work. A 'west vein' was prospected on the 400-ft. level and was reported 7 ft. wide. The total production was estimated by C. H. Dunton, former superintendent, to have been about $125,000.
Lookout Mine, in the Mariposa slate one-half mile southwest of the Union Mine, was located about 1860 and has been worked intermit- tently in a small way since. It has been a small producer of gold pockets. Since 1912, when a production of over $2,200 was reported, there had been no recorded output until early in March, 1933, when Arthur Seymour, lessee, reported a production of $15,000. The mine has been worked through an adit over 600 feet long. Seymour reported the strike was made in the roof of the adit, where a raise was started 520 feet from the portal, and 270 feet below the surface.
Lucky Marion Mine, a mile west of Greenwood, occupies part of the contact of a dike of serpentine with the Calaveras formation. It was worked in 1896 and 1897, and had an incline shaft 112 ft. deep and a 20-stamp mill. From 1897 to September, 1899, it was shut down on account of litigation. Thereafter, in 1901, it produced $3,860. No tonnage figures are available, but the ore is believed to have been 'high-grade' from a greenish quartz stringer 18 inches to 2 ft. wide. There is no further record of production.
Martinez Mines (formerly Hillside Group, with some later loca- tions). The claims are on Martinez Creek, 4^ miles by road south- east of El Dorado and south of the Union Mine. The workings are in Mariposa slate east of the 'bull quartz' vein. Holdings cover 4500 ft. in length on the strike.
Little work has been done on the claims since 1926. During that year, a few men were working through a short adit, winze and drifts reaching a depth of 86 ft. below the outcrop on Hillside No. 3 claim. The slate there dips west and ore is found in small stringers, seams and floors which lie nearly flat, with a slight dip west. Ore was hoisted by hand in a small bucket and taken about one-half mile by sled to a small 5-stamp mill beside the creek. The scanty water supply in summer permits of milling only a few tons of ore at a time. The returns from the small tonnages milled from 1923 to 1926 inclu- sive varied widely, as might be expected, ranging from less than $4 to over $80 a ton.
In 1926 an adit was run 900 ft. into the lower part of the hill and this adit would have to be extended 300 ft. further to be directly under the workings first described. This would give 230 ft. greater
MOTHER LODE GOLD BELT 31
depth than that in 1926. There is a compressor and other equipment at this adit.
At a distance of 700 ft. south of the recent work, an old adit 600 ft. long crosscuts the vein. Between the two, another crosscut 70 ft. long reveals low-grade quartz and is thought to be on the Red Top spur vein. The 'bull quartz' vein of the Mother Lode traverses the Martinez claim, 300 ft. west of the Hillside No. 3 workings. Still farther west, on the Climax claim, are early-day Mexican workings.
Miller (Rihhon Rock) Claim adjoins the Superior Claim on the north. Hayward and Lane prospected the two claims in 1900. The shaft reached an inclined depth of 400 ft. (320 feet vertical). As this work was done at a time when the State published few records, noth- ing definite is known of the results. The vein in the shaft is said to be 2 to 4 ft. wide. There is no record of production.
Montezuma Mine near Nashville had supplied ore for many arrastres in the early days of California mining, but the principal shaft was flooded from 1871 to 1899. The ore that came from the property during that period was from numerous other shallow work- ings which prospected the vein for a length of 1200 ft. Production was about $2,000 in 1890 and a 5-stamp mill was operated irregularly during the next ten years.
In 1899 the old shaft was unwatered and the mine was active until 1907, with 10 stamps in irregular operation. From 1901 to 1907, not including 1905 and 1906, the Montezuma produced $41,071 and the recovery varied from $1.70 to $12 a ton. In 1905 and 1906, Gross and Kleeburg of New York had this mine and the adjoining Havilah under option. They crosscut 47 ft. on the 1200-ft. level of the Havilah and drifted north a reported length of 1285 ft. It is claimed that ore was found, but details are lacking.
Meanwhile, a new shaft had been sunk 360 ft. on the Montezuma 300 ft. south of the old 360-ft. shaft. In the old shaft, ore had been stoped to a depth of 120 ft. and a maximum length of 250 ft. In the new one the principal stope was 100 ft. long and extended from No. 3 level upward for about 175 ft. just south of the shaft. The vein here was reported 8 ft. to 20 ft. wide ; but the dimensions given must be in error as the tonnage indicated would be greatly in excess of actual production.
In 1914, California Exploration Company leased the mine and sank the new shaft from 360 to 1000 ft. inclined depth (899 ft. vertical), starting in the hanging-wall slate. Three new levels were turned, called 500-, 800-, and lOOO-ft. levels. No. 5 or 800-ft. level, which showed the most promise, was drifted 315 ft. north and 100 ft. south and east, with assays indicating possibilities on the north side for about 150 ft. in length. The 500-ft. level explored a total length of 250 ft., partly in each direction, and the 1000-ft. level was run south 200 ft. The war is said to have caused cessation of work.
In 1927 and 1928 a production of a few hundred tons of $10 ore was reported from the Montezuma. In 1931 W. Price and asso- ciates formed the Nashville Mines, Ltd., and reopened the shaft and levels down to and including the 1000-ft. level. A 10-stamp mill was started February 3, 1932, and during part of that year crushed 35 tons of ore daily. On the 800-ft. level a length of 180 ft. was opened.
32
EL DORADO COUNTY
MOTHER LODE GOLD BELT 33
A raise was made from 1000-ft. to 800-ft. level and a drift started about midway between was called the 900-ft. level. On the 1000-ft. level, ore was found in a spur vein after running a new crosscut 125 ft. south of the old one. Where this spur entered the main fissure good ore was found and had been followed 40 ft. on the spur vein at time of visit in 1932. Later this spur was found to give about 100 ft. of stoping length on the 900-ft. level. Ore was reported 12 ft. wide on the 900-ft. level and 8 ft. wide on the 1000-ft. level. The main Mother Lode fissure, however, did not show much pay in this section. This company crushed over 3000 tons of ore which yielded about $8 a ton, with tailing carrying $1 to $2 a ton.
In January, 1933, they were succeeded by Montezuma-Apex Mining Company, a subsidiary of Utah-Apex Mining Company. The latter has greatly expanded the scale of operations, erected and put in commission a new mill (see fl.ow sheet under Metallurgy), and has operated steadily since with results which they state are satisfactory. From 60 to 100 men have been employed and in June, 1934, about 2| tons of ore per man-shift was beingi produced.
The vein dips on an average of 60° E. with Mariposa slate walls in most places, though in some parts the hanging wall is a gray schist or 'mashed sandstone,' and small strips of greenstone are interbedded with the slate. The shaft has been extended to 1300 ft. inclined depth, and 1100-ft., 1200-ft. and 1300-ft. levels opened. The shaft dips about 66° E. and at 1300 ft. is 148 ft. from the vein in the footwall. The Havilah and Montezuma shafts are about 1000 ft. apart, and both mines are being worked ; the .1200-ft. level was being driven south toward a point under the Havilah shaft. The 1200-ft. level of the Havilah, driven years ago under the Montezuma (see ante) corre- sponds to 1050 ft. inclined depth in the Montezuma. Besides the work on the spur vein which was stoped 100 ft. long between 900- and 1000-ft. levels and less than that below, a new ore shoot has been found and is being worked in the main vein. On the 1200-ft. level, this showed 570 ft. in length, most of it ore, in June. For 250 ft. this is reported to be 6 ft. wide, and the balance 4 ft. wide besides a heavy gouge, varying from 2 to 5 ft. thick on the footwall. The gouge is said to carry about 0.1 oz. of gold along the ore body. This ore body extends from 100 ft. north of shaft to over 400 ft. south of it. On the 900-ft. level, two faults moved the ore westward going south ; one strikes N. 60° E. and the other east, but ore is found south of them. An anticline was also noted which arched up the spur vein between 1000 and 1050 ft. depths, as if the hanging wall had moved upward.
A system of modified shrinkage stoping is used where the gouge is not too heavy. In starting stopes timbers are put three sets high (two above the drift). Grizzlies with 10-inch spaces are installed every three sets (18 ft. center to center) on top of the second set with bulldozing chambers, protected by heavy timbering on top of third set, and chutes 18 ft. apart. Above in the stopes stulls are used as required. With wide gouge or faulted ground square sets are used.
On the surface, a 12 by 16 in. Knight crusher and Gyrex screen reduce ore to 1^ inches for the Marcy mills. The hoist is driven by 125-h.p. motor. Two compressors are operated by 150-h.p. and 75-h.p. motors. About 240 tons of ore was being milled daily in June, 1934.
3—4156
34
EL DORADO COUNTY
Very creditable costs were reported from this mine for early 1934. The total for extraction, exploration, hoisting, tramming, milling, and amortization, including indirect costs, was given as less than $4 a ton. With increased tonnage, using both Marcy mills full time, it was believed this could be lowered. Poles for timbering are bought locally, costing about one cent per linear foot per inch of diameter, but it was stated that sawed Douglas fir could be brought from Coos Bay at less than local dealers quoted.
Ophir mine and mill, two miles south of El Dorado.
Courtesy of The Sacramento Bee
Ophir Mine is two miles south of El Dorado in the footwall of the Mother Lode. The workings are in and near the brecciated zone at the contact of diabase and its various phases with quartz porphyrite. A vein from a few inches to 14 inches wide had been followed 98 ft. west on a very flat dip. Near the face the dip steepened and a wdnze was being sunk here. In this winze, high-grade ore occurs in narrow stringers where a dike showing flow structure and containing iron sulphide and arsenopyrite occupies the contact of basic porphyry on east and agglonierate on the west. This agglomerate forms the ridge running north on the west of the workings. It contains corroded
MOTHER LODE GOLD BELT 35
fragments of the basic porphyry, others of a more nearly granitic phase, and some of the dike rock, all cemented by a greenish gray breccia.
About 100 ft. east of the adit portal a shaft had been sunk 36 ft. on a quartz seam that had widened to 18 inches with a reported value of $7.50 a ton.
A 2-stamp mill was put on this property early in 1933.
Oro Fino Mine is a mile south of Garden Valley in a narrow strip of amphibolite schist. The vein where seen was 4 ft. wide, strikes northwest to north and had been opened to a depth of 80 ft. with a dip of 50° when visited. Ore was hauled to the Frog Pond mill in 1926 and the small tonnage crushed gave good returns. In 1930 a few tons of high grade was reported.
Orum Mining and Development Company 's property was idle when last visited, and the shaft was full of water to the collar. There was a mill of 5 stamps, one concentrator, two gasoline engines, an old com- pressor and a jackhead pump. It is on Martinez Creek near the Union Mine.
Pacific Quartz Mine at Placerville is one of a large group of min- ing claims owned by Placerville Gold Mining Company, extending for three miles along the Mother Lode, from a mile south of American River to Weber Creek ; numerous placer claims are also owned, hold- ings comprising 1400 acres in all. Many of the claims were early-day producers of which only a fragmentary history remains.
Pacific mine was found in 1852 and had a 2-stamp mill in 1854. From then until 1861 the production was $480,000 the mill having been increased to 4, 10 and finally 20 stamps. The production up to 1883 was about $1,000,000, and some production was made up to 1889 when $6,000 output was recorded. It then lay idle 20 years; reopening started in 1910 but was suspended. In 1914 a 5-stamp mill was built and small tonnages of ore that yielded about $5 a ton were crushed then and in 1915. This was partly from the dump and partly from the talc orebody.
The principal productive vein was the Pacific on the west side of the lode. The Pacific shaft was sunk 700 ft. vertically and ore was stoped from the 500-ft. level to the surface. This vein was thought to have been lost by being faulted eastward between the 300- and 400-ft. levels. Later work in that direction failed to reveal any ore. As described in 1888, this ore-shoot was 150 ft. long and the average width of vein was 12 ft. Professor Thomas Price stated the ore milled from $6 to $18 a ton with a tailing loss up to 75 cents a ton. The concentrate made up one-half of 1% of ore and con- sisted of "arsenical pyrites or iron, containing 3% nickel and assaying $85 per ton in gold and $2 per ton in silver," according to him.
The shaft is in the black slate of the footwall at the 700-ft. level, where a crosscut east 85 ft. cut a talcose orebody 75 ft. long by 7 ft. wide. The black slate hanging-wall was encountered 130 ft. farther east in the crosscut. From the 700-ft. level 200 ft. north of the shaft a winze was sunk at an angle of 70° for an inclined depth of 1365 ft. This winze entered the footwall slate at 1600 ft. in depth and con- tinued in it to the bottom.
36
EL DORADO COUNTY
The vein here was in an ankerite zone and was ribbon rock in places colored by mariposite. This zone was 300 ft. wade at the 700-ft. level and 125 ft. wide on the 2000-ft. level where cut in drill-holes. Extensive diamond drilling was done from the 1700-ft. and 2000-ft. levels, but over 8000 ft. of holes drilled are said to have failed to show ore.
There is a 5-stamp mill and other equipment at the Pacific shaft in Placerville.
Pocahontas Mine, three miles south of El Dorado was opened in 1854 and in 1867 had a 10-stamp mill. The mine was then yielding ore averaging $15 a ton from a vein 4 ft. wide, and had repaid all expenses of opening and equipment. Work continued intermittently until 1896. Two veins occur, the Pocahontas being 4 to 9 ft. wide and the Empire, 300 ft. distant and 20 inches wide. Both dip east, the Empire being the steeper ; the strike is curving, about northwest. The mine workings are in a feldspathic porphyry variously classified as diorite-porphyrite or quartz porphyrite. This rock is a phase of the large body of granitic rocks of varying composition lying to the north and northwest, around which the Mariposa slates take a curving course northeast and north. The body of rock enclosing the veins on this property has intruded the Calaveras rocks and the diabase on the foot- wall of the Mother Lode. On the surface, the contact of the Mari- posa slate is about a mile east. The claims cover 3000 ft. on the strike.
The mine was worked through two shafts, the Burlingham incline 400 ft. long (205 ft. vertical depth) and the Burke 45° incline 300 ft. deep, south of it. They are 157 ft. apart on the surface but diverge in depth. The Pocahontas vein was drifted north 500 ft. and south 200 ft. on the 100-ft. level and a total of about 1000 ft. on the 300-ft. level of the Burlingham shaft. The ore was stoped out to a depth of 400 ft. on dip and for a length of 300 ft., being 10 ft. wide between 300-ft. and 400-ft. levels. From the 400-ft. level about 150 ft. south of shaft a winze was sunk 125 ft. which is said to have struck a gouge 5 ft. wide carrying pieces of ore, and this may indicate a dip slip or a contact ; the walls changed to slate near the bottom of winze ; this is probably Calaveras slate.
The ore varied in value from $4 to $25 a ton. The amount of water was moderate in the mine.
Poverty Point (Guildford) Mine, two miles north of Placerville, covers nearly a mile along the course of the Mariposa slate. Claims in this group are Iowa, Hidden Treasure, Bantam, Baltic, Humming Bird, Poverty Point, Brighton, Bell and Fortuna. The ground is on the south side of the the river canyon and the topography made possible development through adits, of which four have been run. These have permitted low operating cost. It is claimed locally that the mine has produced about $500,000. There is a record of a little over $200,000 output since 1901, of which nearly all was produced between 1912 and 1917.
Two ore-shoots formerly' mined were stated to be 420 ft. and 200 ft. long. The former was mined for a width of from 3 ft. to 20 ft. Recently a body of low-grade 'schist ore' from 2 ft to 10 ft. wide has been stoped for about 200 ft. in length. Ore shoots occur in a zone of schist and slate 30 ft. wide wdth a footwall of altered amphibolite
MOTHER LODE GOLD BELT 37
schist or similar greenstone, which intrudes the slates in a long narrow dike. So-called east and west veins have been distinguished about 30 ft. apart. The hanging-wall or east vein had the larger shoot. Ore is composed of 'stringer leads' in the slate or schist. The average Avidth is said to have been 5 ft. During the principal recent period of operation, under Guildford Gold Mining Company, the ore aver- aged during favorable years from $4 to $5 a ton. The concentrate, chiefly pyrite, ranged from 3% to 3^% of ore in such years, and carried about six-tenths of the gold and silver ; this concentrate varied from $40 to $88 a ton in yield.
The Guildford Gold Mining Company quit work in 1917, after running the River adit level (150 ft. above American River) 600 ft. In 1919 the mill containing 15 stamps burned, and the property was idle except for a short time in 1920, until 1923 when El Dorado County Mining and Development Company began work, and advanced the River adit level 685 ft. They installed ten 1000-lb. stamps but milled only a little ore in 1925. Some time later the Golden Horseshoe Min- ing Corporation took the property and have been working it in a small way since. They have sunk a winze below the old 500-ft. level adit which was 127 ft. deep in February 1932. They made a small pro- duction in 1931.
River Hill Group covering 178 acres of mining claims and mineral rights 1? miles north of Placerville, includes the Gentle Annie mine, which was a producer previous to 1899. Its shaft had then reached a depth of 600 ft. and there were 4000 ft. of drifts. This mine had a 10-stamp mill. After the death of Melton, the owner, the property was enlarged by adding adjoining ground and the River Hill shaft was sunk and connected at 400 ft. with the old Gentle Annie workings from which ore was taken in 1901 to supply the new 20-stamp mill. In the next three years this new shaft reached a depth of 1050 ft. and finally was sunk to 1550 ft. A drainage adit 2400 ft. long also con- nected with the 735-ft. level. There are five veins on the property, including the so-called dolomitic vein, similar to the second one men- tioned under Pacific Mine. The shaft was between two of these veins, which were opened by crosscuts from the 300-, 400-, 500- and 700-ft. levels. The River Hill was an important producer from 1901 to 1906 inclusive, yielding from $2.50 to $4.80 a ton.
The hanging and footwall veins were separated by a horse of slate 5 ft. thick, according to "W. E. Christian. "With a width of 30 to 40 ft. between walls, ore was sometimes 20 ft. wide. Below the 1000-ft. level, a fault crossed the veins from the footwall to the hanging Avail and is said to have cut off ore. Ore-shoots were 200, 150 and 80 ft. long, according to Christian.
Eolert Veerkamp prospect is in NW^ of Sec. 33, T. 12 N., R. 10 E., six miles north of Kelsey by road. It is on and near the contact of Mariposa slate and a long, narrow diabase dike which runs northwest along the west side of the Mother Lode, about one mile west of the main lode. The land has been farmed for many years and only shallow prospecting has been done.
Two veins occur here — one a heavy barren or low-grade, Avhite quartz vein striking N. 25° W., which is faulted to the west, looking north, by a smaller vein of bluish quartz carrying sulphide, and strik-
38
EL DORADO COUNTY
ing N. 15° E, The latter vein is claimed to assay well in places. The reddish soil on the summit of the hill, and in the obtuse angle between the veins carries gold and some shallow drill holes are reported to have indicated possibilities of a considerable tonnage of ore. The material is so much decomposed and the work is so shallow that it can not be determined whether this gold comes from weathering of one or both quartz veins, from ore at the intersection of the veins, or is from the upper, oxidized part of a disseminated sulphide orebody or stringer lead in the diabase; the latter appears probable.
The land had been taken under option in March, 1932, and some work was planned.
Sherman Mine is a mile north of Placerville, south of Big Canyon Creek. The principal period of production began in 1908 (though there had been some output in 1905) and continued through 1911. The total production during that period was about $136,000. The yield per ton varied from $3.15 to $6.50 and average width of vein was reported to be 5 ft., with two ore shoots 60 ft. long, between walls of Mariposa slate.
A shaft was sunk at an angle of 74° (the dip of vein) to a depth of 750 ft. and at a point 1250 ft. north of shaft on the 750-ft. level a winze was sunk on the vein 350 feet deep. Most of the drifts were run north, the total length drifted on vein varying from 250 ft. on 100-ft. level to 1400 ft. on 400-ft. level. Most of the gold and silver were obtained from the concentrate, which was principally pyrite and formed 3^% to over 4% of ore. It was worth from $66 to $91 a ton.
The plant comprised a double-drum hoist, large compressor and ten 1000-lb. stamps with 2 crushers and 5 concentrators.
Sliger Mine was found in 1864, and was known as a producer of specimen gold ore, though the gold was more evenly distributed than in many nearby mines. By 1874, an adit had been run 375 ft., cutting the vein at a depth of 200 ft., and a shaft was sunk to connect with it. The ore then was said to come on the footwall side of the quartz vein, in north-raking shoots. The ore was crushed in a small mill and the production was estimated at $125,000 to a depth of 170 feet. Later operators sank to 300 ft. and are supposed to have produced $100,000 more but made no accounting.
Little was done thereafter until 1922, when Sliger Gold Mining Company was organized, and the shaft was sunk to a depth of 500 ft. on the dip of vein. Milling began in January, 1929, and good ore was produced during the two following years. In the attempt to make the mine pay its way, the shaft was not properly protected and caved in early in 1931.
The country rocks are amphibolite, slate and serpentine, the latter forming a narrow dike. The mine is at the contact with black slate on the footwall and ankerite and serpentine on the hanging wall. A strip of slate was probably caught up in the intrusive from which the amphibolite was derived.
On the 350-ft. level, the crosscut was driven in a curved course for 33 ft. throueh ankerite or similar mixed carbonates, stained by mariposite. and likeAvise on the 500-ft. level. At the time of visit, a raise had been put up in ore between these two levels, and ore had
MOTHER LODE GOLD BELT 39
been stoped for a length of 60 ft. and a maximum width of 19 ft. and a height of 30 ft. above the 500-ft. level.
The principal orebody seen is on the footwall side and is a replace- ment of an igneous member of the amphibolite schist series, probably a dike. It is now highly silicified, with some carbonates,- and is thickly impregnated with fine crystals of sulphides disseminated through the rock. The ore has no definite wall but merges into low-grade rock. There are two classes of ore in this part of the mine — so-called black slate or schist ore and grey-schist ore. On the 350-ft. level, a drift had been run 260 ft. north and was claimed to be in ore for 110 ft. ; on the 500-ft. level, the drift was 220 ft. long on the north side of shaft at time of visit, of which 120 was claimed to be ore, which varies in width from 14 inches to 19 ft. wide. This ore is hard and requires little tim- ber. Most of the pay is in the sulphides which make up 3.7% of ore, and contain from $75 to $375 a ton, nearly all gold. The concentrate con- sists almost entirely of pyrite. The smelter assay of one lot of con- centrate was:
Au 10.71 ounces
Ag 0.6 ounce
Sb 0.7%
Insoluble 23.2%
Iron 31.0%
Sulphur 32.5%
As 0.6% (in some lots)
Freight and smelter charges were $22 a ton. The operating cost was low at that time. Ore was being milled with 15 stamps of a total of 25. A 40-mesh screen was used, and a discharge only 2^ inches high. Recovery was said to be about 80%. Ore value ranged from $5 to $15 a ton. Seven men employed were producing and milling 18 tons of ore in two shifts.
In October, 1931, C. L. Wright of New Jersey and associates took a lease on the mine and reclaimed the shaft. A 100-ton ball-mill and flotation plant were installed late in 1932. Early in 1933, Middle Pork Gold Mining Company was formed to continue work which has been carried on continuously since. The underground workings have not been visited by the writer since ,1930. In 1932, a winze was sunk 100 ft. from the 500-ft. level and a drift 200 ft. long on the 600-ft. level was reported by Charles Mayotte, then superintendent, to be all in ore, which crosscuts showed to be 32 ft. wide. He believed over 100,000 tons of good ore was reasonably assured, of an average grade of about $10 a ton.
In that year, work was started on the surface outcrop of the vein near the south boundary of the Sliger claim. Shortly after, suit was started by Paul Ricci, the owner of the adjoining South Sliger claim. This was terminated in 1934 by the purchase or lease of the latter claim in July, 1934, by Middle Fork Mining Company.
Stamps have been displaced in the present mill, which uses a ball- mill, flotation and gravity concentration. Two-stage crushing with Blake and S.>Tnonds crushers is used ahead of the ball-mill, which works in closed circuit with two Dorr rake classifiers. From the mill, pulp passes over a Deister Overstrom concentrator which saves per- haps 75% to 80% of the gold in a high-grade concentrate. The table tailing is sent to a conditioner, then to six Kraut rougher cells and
40 EL DORADO COUNTY
two cleaner cells. Concentrate is hauled by truck to Selby smelter. Mill capacity is about 70 tons a day. A high recovery is being made. In 1934, a crew of 40 men in mine and mill was producing about 50 tons a day. This property should be a profitable producer for several years.
St. Lawrence Mine. The following claims are included in this group : North St. Lawrence, St. Lawrence, St. Lawrence No. 2, Guada- lupe and the St. Louis, which is adjacent to the St. Lawrence on the east, and the St. La^vrence mill site. The property is about eight miles north of Placerville on a good road at an elevation of about 2000 ft.
The original location was made in June, 1867, by placer miners who had followed the rough coarse gold upstream on Irish Creek and Dutch Creek until they found the vein. The locators worked the mine until March, 1871, when it was bought by Bateman and Company, who put up a 20-stamp mill and continued the sinking of the shaft and the opening of levels at intervals of 100 ft. The mine at the time of this sale had reached a depth of about 600 ft. on the dip of the vein.
In a contemporary description of the property it was stated that the quartz in the St. Lawrence occurs in lenticular forms not continuing for any great distance but invariably found to come in again in similar veins lying along the main fissure. At a depth of 550 ft. in the main shaft the quartz is said to have entirely given out and gouge took its place, following the well-marked footwall. At the 500-ft. level, 160 ft. north of the shaft, the quartz gave out and there was in its place a 5-ft. gouge showing slickensides on both walls. Before giving out in this direction, the quartz jumped several times from the hanging wall to the footwall and vice versa. The underground aspect appears to have been similar to that of other mines in the Mariposa slate as the apparent hanging wall is said to be repeated two or three times in parallel slickensides.
In sinking the shaft from the 500-ft. level to the 780-ft. or eighth level the work was in this broken-up ground.
The English company failed to supply money to carry on pros- pecting work when the grade of rock taken out of the lower levels became too low to pay expenses. The mine was attached by creditors in September, 1874, and was sold to persons who started mining in May, 1876, and after reaching the ninth level sank a A^dnze 200 ft. deeper in the search for the continuation of the upper orebody. In the eighth level north of the shaft they found the apex of a rich lens of ore which proved to be very small. The deeper work from the ninth level do'^\Ti resulted in the discovery of no new ore Avorth mentioning.
The record of the value of ore and the total production of the mine is not complete. The original discoverers took out ore worth $10 a ton. The English company could not work at a profit ore that went less than $8.54 per ton, as is shown by a letter A\Titten by their superintendent in 1874 when he advised against running the mill on ore of that grade. For the year 1873 this company's reports showed 8062 tons milled: bullion p^roduced, $141,002.13; average per ton, $17.49. The small lens of ore below the eighth level is claimed to have paid $27 per ton and to have yielded about $18,000. In a statement by Lieutenant George M. Wheeler in 1878. he says the St. Lawrence up to that time had produced .$465,000 and had cost $300,000. The mijie has been
MOTHER LODE GOLD BELT 41
idle since. This vein was explored: for a total length of about 200 ft. north of the discovery shaft and 194 ft. south and so far as known liractically no crosscutting was done after the pay-shoot disappeared. The recoveries noted above were of free gold only.
Sunrise Mine, one mile northeast of Kelsey, near the Dalmatia and supposed to be on the same vein, was another low-grade deposit that made a record for low operating cost. Although equipped with a 10-stamp mill in the 1890 's, it was worked only in a small way and irregularly". Though several crushings of ore were made, and an operating cost of 63 cents a ton was claimed, there is no record of the amount of gold produced.
Superior (Tin Cup) Mine, one mile east of Diamond Springs and adjoining the Larkin on the north, was located in 1867 as the Reid mine. It is described in detail in Report VIII of the State Mineralo- gist. At that time it had been explored to a vertical depth of 160 ft. by a steeply inclined shaft 180 ft. long, and two adits, one 250 ft. long and one 700 ft. long. It had a 10-stamp mill. The yield of ore varied from $5.80 to $15 a ton, and concentrate worth $130 a ton made up 5% of ore. The tonnage of ore was, however, small and the mine was closed soon after. It remained idle until prospecting work Avas started in 1900 by Hayward and Lane upon it and the adjoining Miller claim on the north. Hayward purchased the Superior claim, but nothing is known of his short-lived operations beyond the fact that prospecting finally reached an inclined depth of 400 ft.
Taylor (Idlewild) Mine on the westerly section of the lode three miles southeast of Greenwood was found in 1865. At the surface the vein was two feet wide, but increased with depth and an average width of 14 ft. was stoped during the best days of the mine. The footwall is hard greenstone which runs through the property in the form of a narrow dike. Mariposa slate forms the hanging wall. A well-defined gouge occurred on the hanging wall, and considerable trouble was caused by swelling ground. Stopes were filled with mine waste and with surface rock dropped through a chute. The shaft for the first 300 feet was sunk in the vein then passed into greenstone.
The mine was reopened in 1888 after lying idle ; in that year it had a 10-stamp mill and produced $4,000. In 1890, 10 more stamps Avere added, and the 500-ft. level was opened and was producing 20 tons of ore a day, which averaged $6 a ton. The orebody was reported 30 feet thick on that level, consisting of "quartz, lime, feldspar, slate, etc." Within two years the mine became the principal producer of the county. The levels, 100 ft. apart, explored and developed an ore-shoot 400 ft. long. Below the 500-ft. level, according to E. J. Kendall, superintendent of the mine for 13 years, the orebody decreased in size with no quartz below the ninth level. Crosscuts were run about 100 ft. on the 10th and 11th levels without results, and drifts were run southeast 600 to 700 feet (probably to the property line) on the 200- and 300-ft. levels. The shaft was "sunk to 1225 ft. on an incline of about 50° before work ceased.
Apparently there is no complete record of the mine's output, the owner claiming tonnage records were lost by fire in 1906. Beginning in 1893 and continuing several years, the annual output was from
42 EL DORADO COUNTY
$146,000 to $150,000. The mill capacity in 1893 was 110 tons a day with 40 stamps. Estimating an average monthly run of 3000 tons would indicate an average recovery of about $4.16 a ton. This, how- ever, is at wide variance with the statement of E. J. Kendall who said ore averaged $8.40 to $8.55 a ton. It is known the best ore was on the hanging wall. The gold was finely divided as a rule, but at times in sheets. Ore is described as typical 'ribbon rock.' Sulphides which were of good grade in the earlier operations became too poor to ship and concentrate was later cyanided at the mine. The mill capacity was increased again in 1896, and the value of heads dropped because of increasing tonnage handled. There is no record of output after 1900. The total production has been estimated at about $1,000,000. The amount of dividends, if any, is unknown. But with production averaging about two tons per man-shift for all employees, and with cheap water power and timber, there should have been a fair return, for a few years at least.
Union (Springfield) Mine. Although this mine is credited with being the largest gold quartz producer in the county, there has been little definite information available concerning it. Most of the work was done upon it many years ago by operators who refused to divulge results of their operations, and part of this activity was during a period when the State was not publishing reports on mines. In the period since 1916, the property has been idle and has belonged to nonresident owners who have kept the records outside the State and have failed to supply information requested. It is believed that the production has been overestimated, as is common in such cases.
The surface of the present holdings (see claim map) supported a large mining population in the early 1850 's, and the float ore was worked in arrastres after the stream placers were exhausted. Professor Silliman induced his relatives and friends to finance quartz mining and the Union and Church (later worked as separate mines) were con- solidated. A pay shoot north of the Union shaft is said to have yielded $450,000 from 15,000 tons of ore mined before 1868. The Cosumnes vein croppings and shallow workings on it west of the Union to a depth of 120 ft. are said to have produced $150,000 more. In spite of the good grade of ore found, the project failed and the mine lay idle several years until Alvinza Hayward and Hobart purchased it. They changed the name to Springfield and operated about 15 years. They had a mill of fifteen 600-lb. stamps with a capacity of only 26 tons a day. Concentrate worth $150 a ton was saved on Frue vanners and treated by chlorination. In ,1886, near the latter end of these opera- tions, it was stated'^ that the ore-shoot (probably meaning series of shoots) was 800 ft. long and the vein averaged three ft. in width. The Springfield shaft was finally sunk to a depth of 1640 ft. (vertical), and the Clement shaft 900 ft. deep on an incline of 70°. Over 21,000 ft. of drifts and crosscuts are reported to have been run.
After an idleness of about 10 years, Union Gold Mining Company began work and a 30-stamp mill was built. In 1897, a production of $36,000 was reported. From then until 1909, only estimates of pro- duction were made public. These indicate that from 20,000 to 40,000 tons of ore was crushed annually, yielding from $5 to $7 a ton. In 1909, the last year for which a figure is at hand, 12,000 tons yielded
1 Sixth Report of the State Mineralogist, pt. 2, p. 43, 1886.
MOTHER LODE GOLD BELT 43
a little over $5 a ton. During this period, the same company operated the Schoolgirl workings, west of the Union, and separate figures for the two are not available. The latter had a 20-stamp mill.
The Union was again reopened in 1914-1916 and some prospecting was done, but the results of this were disappointing.
Five veins striking about N. 16° E. occur in the Mariposa clay slates on this property. They dip 60° to 79° E. and are reported to be 5 ft. to 10 ft. in average width. The main or Springfield shaft is 320 ft. east of the hanging-wall vein at the surface, crossing the vein at the 1200-ft. level. The west gouge vein was also crossed by this shaft about 60 ft. above the 1600-ft. level. Four ore-shoots, varying from 100 to 250 ft. long, are said to have been worked out from the 1300-ft. level to the surface. The work done up to the time Hayward and Hobart quit had been done almost entirely on the southernmost 1000 ft. of the property. When they drifted farther north, it is said the vein broke into stringers. Under Harpending (1896-1909) a crosscut was run east to search for the vein which had either been faulted or had turned east. They struck a vein 1400 ft. north of the north end of the Springfield old workings and 700 ft. south of the Church line. Ore was opened here 230 ft. long in a winze and it was from here that much of the later production came.
Late in 1934, Gold Fields American Development Company began unwatering the Springfield workings for the purpose of further pros- pecting under ground. About 30 men have been employed. An electric power line was built and pumps were started at the end of July. J. T. Boyd is manager.
War Eagle Claim is the south extension of the Big Chunk. It has been a pocket producer only. There is an old shaft believed to be 80 feet deep with which an adit 150 feet long connects. This adit shows a vein about 18 inches wide.
Seam Mines
Along the Mother Lode in El Dorado County beginning at Placer- ville and extending into Placer County, a peculiar kind of gold quartz deposit has been extensively worked by the hydraulic process. They liave been known from the earliest days of mining in that region as 'seam mines' or 'seam diggings.' These deposits occur in both the Mariposa clay slate and in the amphibolite schist. They consist of broad and rather well-defined lodes in which the gold occurs generally in narrow veinlets of quartz and at times in the gangue rock itself. In these lode zones, which are sometimes nearly 100 feet wide, there may be several systems of quartz veinlets, each system having a definite strike and dip within the main lode. Generally these stringer systems are bounded by the main lode walls which are often quite definite. At times in such a lode the quartz stringers may increase in size to solid lenses several feet wide. In such cases it may be difficult to say whether a mine should be called a 'seam mine' or a quartz mine. The pay in the seams occurs as a rule at the intersections of two such stringer systems or perhaps where the stringers of such a sj^stem intersect one of the larger lenses of quartz. At Georgia Slide, for example, there are three systems of seams. One system strikes northeast and dips 45° northwest; another stands nearly vertical with a northwest strike and the third which follows the strike of the schistosity of the schist and
44 EL DORADO COUNTY
slate a little north of northwest, dips 75° east. The principal pay in this property was found at the junctions of the first and third seam systems and on the side of the quartz away from the so-called sand streaks.
The peculiar circumstances found by the early miners who first investigated these deposits led them at once to experimentation with the only methods of mining they were acquainted with at the time. They found that these seam zones were decomposed to such an extent that a large part of the gold in the upper portions of the deposits could be saved by the ordinary sluicing and hydraulicking methods, as there was available at the time considerable water for mining. This method of operation came into quite extensive use through that entire section even during the decade between 1850 and 1860 and continued up to the time of the prohibition of hydraulic mining. There are few definite records of actual results of these operations but such figures as are available are extremely interesting. The following are some of the results as reported in 1874 by Amos Bowman :
The Grit mine at Spanish Dry Diggings from 1860 to 1867 pro- duced $100,000 but a great deal more had been taken out as early as 1852 and it was estimated that the mine had produced in all $300,000. The Beatty mine at that time had been worked for 17 years and was producing at the rate of $1,000 a month clear of all expenses to the owner of a one-eighth interest. The Frerich claim of Greenwood had produced about $100,000.
Some of these properties, as nearly as can be figured, produced over a dollar a cubic yard and were worked at a cost only a little higher than the ordinary hydraulic mine. As work progressed, how- ever, in these mines it was found the method of operation had a strictly limited application at depths varjdng from a few feet to 60 feet. The seam zones began to show the fresh rock not decomposed by the agencies which had softened the upper part and this hard rock could no longer be worked by the hydraulic method. Due also to the slabby and angular character of the material, these mines had to be equipped with sluices having a much higher grade than the ordinar\^ placer mining sluices so that in mining for any length of over a few hundred feet along one of these seam zones the miner would eventually find the upper end of his sluices coming up to the surface and work would have to be stopped on account of lack of grade.
The most important group of 'seam mines' is that at Georgia Slide, an old mining camp 2 miles north of Georgetown. In its course north- westward through El Dorado County the main belt of the Mariposa slate is separated into two branches by a large lens of amphibolite schist and the Georgia Slide mines are in this schist and on the eastern branch of the slate where Canyon Creek has cut a deep trench across the gold-bearing formations exposing them in cross section in such a way as to facilitate cheap hydraulic mining. The mines here will be de-scribed under the heading of Georgia Slide mines.
The following is a list of the principal 'seam mines' that have been worked in the regions mentioned :
Blasdel seam mine is on Dark Canyon north of Georgetown. This seam belt runs about 2000 ft. in a northerly direction but has not been extensivelj^ worked.
MOTHER LODE GOLD BELT 45
Carrol claim is on the east slope of Greenwood Hill. The pit here was 80 feet long by 40 ft. wide and 15 ft. deep, but the production is unknown. There are three systems of quartz seams of which one in particular has produced gold.
Castile mine between Empire and Manhattan canyons, near Garden Valley. This contains two quartz veins separated by 3^ ft. of slate lying in a seam zone which has been hydraulicked for a length of 100 ft. by 70 ft. wide and 18 ft. deep.
The Cedarherg mine, about a mile south of the Sliger on the east side of American Canj'on had an interesting history. Cedarberg and his partners had prospected without success until thej- had exhausted their funds. Thej' then applied to the water company for one day's free supply of water which was given them, but their flume was in such poor condition that it broke when the water was turned into it and the water in running to waste down the hillside uncovered a quartz vein three inches wide with some parallel veinlets. The part- ners mined out here 90 cubic yards which yielded $45,000 to a depth of 25 ft. As work went deeper on the vein it increased in size to a width of 2 ft. at a depth of 200 ft. An ore shoot 50 to 80 ft. long was worked and the mine was famous for a time as a producer of beautiful gold specimens, the free gold occurring in white quartz and the sulphides in a bluish quartz. Some attempts have been made in later years to bring this property into operation as a quartz mine but these have not met with success.
West of Cedarberg is a seam belt which is cut through by the American Canyon and which contains the George, Smith, American, Conner, and Mauley seam mines concerning which there is nothing of particular interest available.
The Cranes Gulch or Whitesides mine had produced $100,000 from a pit 150 ft. wide by 250 ft. long by 70 ft. deep before 1874. This would indicate an average yield of over one dollar per cubic yard.
French or Nagler claim, which adjoins the town of Greenwood, has an old hydraulic pit of probably two acres in area which has been worked out to a depth of nearly 100 ft. The seam belt here was about 200 ft. wide with porphj^r}^ on the M^est and decomposed slate on the east. From the figures quoted by Bowman it would appear that the production of gold from the hydraulic mining operations here pre- vious to 1874 had amounted to about $100,000 or an average of about $3 a cubic yard but this figure seems excessive. The largest amount of pay is supposed to have come from the intersection of a cross vein with the main vein. A shaft was sunk at this intersection in early days and the ore taken out is said to have milled extremely well. This vein shows mineralized schist with two feet of solid quartz. The record of the water company which sold water to this mine showed that from the total production mentioned over $20,000 had been paid for water or an average of $80 a week.
The Fisk or Porphyry ledge is one-fourth mile north of Placer- ville and has produced large sums. In 1870 Fisk took $3,000 out of a space 8 ft. by 10 ft. hy 20 ft. and the claim produced considerable ore carrying $100 to the pan with pieces weighing as much as 25 to 40 ounces each.
46 EL DORADO COUNTY
Georgia Slide Mines. In this group are the Bhie Rock claim con- taining 27 acres, the Pacific claim of six acres, the Bcatty claim of 26 acres and the Parsons claim of 20 acres. The Beatty claim was operated continuously from 1853 and the Pacific and Blue Rock from 1856 until 1895 when the operators were notified to discontinue min- ing by the hydraulic process. The geology of these claims has already been mentioned. In later years when the rock began to be a little firmer than in the early workings powder was used in large quantities to break down the bank previous to washing with the hydraulic giants. Quartz specimens containing gold Avere sorted out by hand as far as was possible and were crushed in a hand mortar. It has been stated that these properties produced from $2 to $3 a ton in gold which was worth $18.50 an ounce. After 40 years of operation the bank on these properties was 150 ft. deep and an immense amount of tailings had accumulated in Canyon Creek. The various operators had a work- ing agreement by which the grade was lowered at the different prop- erties in such a way as to permit all of them to continue work.
The deposit at Georgia Slide is essentially a large lenticular body some three-fourths of a mile long and nearly 400 ft. wide at the widest point. No close estimate can be made of the total amount of gold which has come from this deposit. Oregon Canyon, which is claimed to have produced $2,000,000 in a length of three-fourths mile, and the lower course of Canyon Creek, which produced $1,500,000, derived their gold from this seam belt. Several millions more were produced by the seam mines mentioned above and there are still remaining a million tons left unworked in the deposits above the level of Canyon Creek. In recent years the deposit has been extensively sampled with the idea of making a large low-grade quartz mine. These plans, how- ever, were never carried out. Several small stamp mills were operated on seam mines here after the prohibition of hydraulic mining. These handled selected ore in a small amount.
Grit mine at Spanish Dry Diggings was first worked by Spaniards, who carried the dirt down the steep canyon to American River to wash it. It was most productive in 1852. Between 1860-1867, it produced $100,000 and in 1865 a mass of beautifully crystallized gold whicli weighed 101.4 ounces Troy, and came from a shaft sunk a few feet below the bottom of the hydraulic pit, which was 50 ft. by 150 ft. by 60 ft. deep. No particular vein was noted until a depth of 40 ft. was reached, where lenses of quartz were found with a maximum width of 3 ft. over a length of 30 ft. These were followed 100 ft. deeper, and the mine then lay idle many j^ears after a reputed produc- tion of $300,000.
In 1919, two men struck rich specimen ore in the vein at the bottom of the old workings and a stock company was formed with the idea of developing milling ore. Although several thousand dollars was produced in crystallized gold, the venture was not a success. The gold occurs in quartz and calcite, with amphibolite schist and slate walls 3 ft. apart, and the lens of ore was 30 ft. long, with the richest values at one end. Both walls here carry considerable pyrite in coarse crystals.
The Sliger mine in Sec. 25, T. 13 N., R. 9 E., and the Hines mine half a mile north of it were both worked in the early days as seam mines and then lay idle for a long time until a few years ago when work was
MOTHER LODE GOLD BELT 47
resumed and both of them have shown promise of developing into good quartz mines. They are mentioned elsewhere in this report.
The Hart mine near and north of the Castile has a seam zone which has been hydraulicked for a length of 175 ft., a width of 50 ft. and a depth of 40 ft. After the fresh rock had been reached in this pit considerable prospecting was done to see if the ore was rich enough to be handled in a quartz mill. An adit was run for a length of 320 ft. which encountered four separate stringer systems or veins all parallel in line within the seam zone. On the first of these veins a drift was run 175 ft. south and on the fourth a drift 70 ft. long was driven. This property has lately been taken under option by J. A. Flink and others. Underground these veins appear as stringer leads in the amphibolite schist. An 8-stamp mill was put on this property in 1930 and a mill test of 11 tons was made from the first vein. Although it was reported that this gave satisfactory results there has been nothing further done with the property until 1933, when work was resumed and is being continued.
The Hodge and Lemon mine is a north extension of the Fisk and is on the north end of Quartz Hill. The seam zone here has been mined for a length of half a mile on these adjoining claims and for several hundred yards there is an old open cut which was 30 to 40 ft. deep, with underground workings of unknown extent below the pit. The cross veinlets in this mine dipped 40° north and rich pay w^as found where these veinlets strike the east wall zone. This zone con- tinues on through Poverty Hill.
The Spanish mine on the hill west of Greenwood has a seam belt 100 ft. wide. An area 400 ft. long by 24 ft. wide when hydraulicked went 800 ounces gold worth $17 an ounce or a total value of $13,600. Much work has been done on this property in later years in the endeavor to develop it into a quartz mine but so far this work has not been successful. The pay was followed 80 ft. below the bottom of the pit and the vein was drifted on 20 or 30 ft. in each direction.
The St. Lawrence seam mine produced $23,000 in 10 months with a crew of four men using 100 miner's inches of water which cost for the above period $8,000.
In the Spanish Dry Diggings district there are three seam belts, the one farthest west having been worked at the Waion mine, the one at Spanish Dry Diggings containing the Grit and the Barr and Cross- ton and the third, a quarter of a mile east of the Grit, called the Fargo belt.
The Waun mine is a half mile west of Spanish Dry Diggings. Four series of seams have been worked, first by the hydraulic method and two of these were followed into the hill by tunneling. This seam belt is 50 ft. wide. The gold occurred in quartz veinlets running parallel to the strike of the seam zone and also intersecting veinlets crossing the seam belt.
The French Hill mine near Spanish Dry Diggings is on this seam belt, one-half mile south of the Waun mine.
The Sivift and Bennett claim at the southern edge of Georgetown paid a good profit in the 1870 's; some of the rock yielded a dollar to the pan.
48
EL DORADO COUNTY
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MOTHER LODE GOLD BELT 55
AMADOR COUNTY
Geology
Most important of the Mother Lode counties from, the standpoint of gold production and mine development, Amador County has also had the highest percentage of successful lode mining operations of any region in the State. With a length of 20 miles traversed by the Mother Lode formations, the section between Jackson and Plymouth, ten miles long, has been most intensively developed and has yielded most of the gold produced in the county.
It is believed that the geologic notes herein under the individual mine descriptions are sufficient to emphasize the most important points, which are only briefly alluded to in these introductory paragraphs.
By far the greater part of the production has been from mine workings in the Mariposa (Jurassic) clay-slate, in the vicinity of contemporaneous, interbedded greenstones now having the aspect of dikes due to the tilting of the entire series, but originally deposited as mud flows of volcanic ash and breccia and other extrusive rocks, formerly called augite porphyrite, later known as meta-andesite. As a matter of fact, the alteration of such originally igneous members found in the mine workings has often advanced so far that even the expert petrographer can not positively name the original rock.
Veins in the slate are typically fissure fillings of white quartz, often ribboned with thin slate layers. The gold in such ore is mostly free; the percentage of sulphides is uniformly small, 1% to 2%; and the amount of gold associated with the sulphides so closely that it is recovered only after smelting or cyanidation, is not generally over 20% of the total. There has been little variation in the character of these ores in the range of about 6000 ft. on the dip so far explored. The ribbon ore of course indicates repeated reopening of the fissure along the walls of the veins, with additions of vein matter.
At depths varying from a few hundred to several thousand feet, the veins pass on the dip from the Mariposa clay-slates into the altered igneous rocks (meta-andesite, amphibolite schist, or as commonly called, greenstone). When this happens, the vein commonh^ flattens in dip, takes on a more massive character, and becomes itself of lower grade, often too lean to make ore; but lenses of a different variety of ore are usually found in the nearby greenstone walls, close to the vein. These are the 'gray ore bodies' or 'schist ore.' They consist of hydro- thermally altered greenstone, or amphibolite schist, containing 2% to 4% of disseminated auriferous sulphide, mostly pyrite. This ore is largely ankerite, but with considerable silica and some albite. Often such ore in the schist is traversed by a network of quartz stringers and is called a 'stringer lead.' From 50% upward of the gold in it is associated with the sulphides. Commonly, though not always, it is of lower average grade than the slate quartz ore.
These gold deposits have been classified as mesothermal, therefore as having been deposited at moderate depths. How much deeper they must be proven to extend before they may be considered deep-seated
56
AMADOR COUNTY
MOTHER LODE GOLD BELT 57
is an interesting question. Of the 'true fissure' type, they have been distinguished from the younger, bonanza type of gold deposit by the persistence of the ore in depth and by the repeated occurrence of ore, usually in lenticular form, particularly on the dip. As a corollary of this, so-called barren zones may be expected sooner or later, through which sinking may have to be carried several hundred feet in low-grade material before another orebody is found.
The ore-shoots are generally so much longer on the dip than on the strike that the old empiric rule regarding these relations cannot be applied. Many of the better ore-shoots can be quite definitely cor- related with the junction of a spur vein or link or cross vein with the main fissure.
In Amador County especially, experience has shown that ore is not necessarily confined to any particular channel in the slate, but may occur in either the footwall or hanging-wall sections or in the middle of the slate, if bodies of interbedded greenstone of sufficient size are there and if other conditions are right. The whole width of the slate, under these favorable conditions, must be crosscut from massive footwall greenstone to hanging-wall greenstone before the possibilities of finding ore can be safel}' considered as exhausted. Massive contact quartz veins however are seldom themseh-es important ore producers.
The general location of the lode was determined by the course of an ancient, pre-mineral major fault zone along which compressive strains (caused by the growth of the Sierra Nevada with the intrusion of its granitic batholith) found relief in rupture with reverse faulting. This fault zone, following here a belt of weak rock (Mariposa slate) and weak contacts (slate-greenstone) was a locus of movement over a long period, favoring the formation of ore by the building up of ribbon veins b}' additions of vein matter on the side next the wall. After the period of compressive stresses there must have occurred subsidence on the hanging-wall side sufficient to open tension fissures, which in many cases helped form orebodies at and near their junctions with the main veins. Some important oblique faults, crossing the strike of the lode, have in several cases limited ore deposition in particular mines. "Whether or not such oblique faults are merely a phase of the post- mineral adjustment, which cut off orebodies, or are pre-mineral faults whose gouges dammed up the ore-bearing channels, is not always clear ; but there has certainly been post-mineral moA'ement on some of them.
The definition, extent and importance of post-mineral faulting are debatable and hard to arrive at because of the homogeneous nature of the slate and the absence of characteristic bands or beds that might be used as markers; also to the relatively small extent of vein opened at one time, and the rapidity with which old workings close.
Although the Mother Lode follows the Mariposa slate across the entire county, the developments north of Plymouth and south of Jack- son have so far not brought in any mines as important as those in the 10 miles between these towns. A little north of Martell the Mariposa slate is separated into two sections by a lens of the altered andesite from a few hundred feet to one-fourth mile wide and from Jackson southward Calaveras (Carboniferous) rocks are in places in contact with the eastern strand of the Mariposa slate. The Zeila and the Hardenberg have been the principal developments on this side, lying in
58
AMADOR COUNTY
the region of the easterly amphibolite schist contact. Between these two mines, there are five or six veins, the Zeila Mine being on the most easterly, the Amador Queen No. 1 occupying several of them of which the 'main vein' showed a width of 60 ft. or more of stringer lead material in the amphibolite schist. There are four such veins or leads in a width of 800 ft. here. No important ore-shoots have been found in this section, between the Zeila and Hardenberg. Quartz is typically in small lenses in the schist here.
The western strip of Mariposa slate running from the Kennedy and Argonaut southeast and south is a very narrow band which carries gold deposits of a kind entirely different than those on the east. South of the Moore Mine this westerly band is known as the Black Metal Belt, containing the Valparaiso, Mammoth and Amador Queen mines, pro- ducers of high-grade ore, much of it in specimen form, with arseno- pyrite which gives rich concentrate. Besides these three mines which have been the larger producers, the McKinney, Crannis, St. Julian and Marlette claims have also yielded pockets.
Geography, Climate, Water, Timber, Power
Amador is the central county of the Mother Lode group, extending from the lower foothills bordering Sacramento Valley on the east, to the summit of the Sierra Nevada. The Mother Lode occupies a rolling, park-like area dotted with small scattered oak trees, crossed by the Cosunines River on the north county -line and the Mokelumne River on the south, and varying in elevation from 700 to 1600 ft. A broad- gauge railroad from lone to Martell, the latter directly on the Mother Lode, connects wdth main-line railroads, and a fine road, part of the State highway system, traverses the length of the lode with good paved highways entering also from Sacramento and Stockton, both about 50 miles distant in the great central valley on the west. The annual rain- fall at the Kennedy Mine ranged from 16 to 55 inches during a period of 30 years, with a mean of 33 inches. Snow is nearly unknown. Most of the rain falls between November 1 and April 30 and the other months are dry. The growing season, averaged 262 days for 17 years. Summer temperatures of 100° or more are not unusual in July or August, but the humidity is so low that heat prostrations are almost unknown.
ANALYSIS OF GOLD PRODUCTION OF MOTHER LODE MINES IN AMADOR COUNTY FOR
CERTAIN YEARS*
Year
Number of mines
Tons of ore
Gold and silver,' aver- age per ton
Tons cone.
Value cone. per ton
Total value, gold and silver
3915
13 19 14
8 7 12
7
815,675 492,103 1£9,076 311,462 286,659 233,675 213,865 182,650
$4 74
6 03 8 31 8 25 8 02
7 12 6 63 6 67
17,155 23,657 3,624 2,844 5,836 4,182 3,962
$79 91 44 71 104 65 114 01 79 63 78 18 75 17
$3,870,010 00
1918 - -
1920 - -
2.968,526 00 1,653,825 00
1924
2,555.625 00
1928
2,2f8,490 00
1930....
1931
1.664.895 00 1,417,836 00
1932
1,219,794 00
* From compilations made by the U. S. Geological Purvey and U. S. Bureau of Mines.
' With silver at $1 an ounce, the silver content of these ores averages only 5 to 6 cents a ton; in 1932, with silver averaging 2S.2 cents an ounce, it amounted to 2 cents a ton.
MOTHER LODE GOLD BELT
59
Though some companies have water rights, the supply comes prin- cipally from a public utility which also controls electric-power distri- bution. The water, used also for generating electricity, comes from reservoirs in the high Sierra Nevada to the east.
Good pine timber is obtainable 15 to 30 miles to the east. Electric power lines, fed from a hydroelectric plant a few miles east of the lode, serve the Mother Lode mines.
Gold ar
d Silver Production
af Amador County, 1880-1933
Year
Gold, value
Silver, value
Year
Gold, value
Silver, value
1880
$1,495,053 1,450,000 1,500,000 1,590.000 2,000,000 2,145,591 1,874,062 1,979,956 1,750,000 1,560,975 1,459,952 1,395,962 1,210,383 1,505,973 1,331,916 1,391,929 1,523,351 1,324,472 1,806,363 1,544,868 1,373,788 1,823,827 1,629,151 1,609,744 2,060,574 2,445,815 2,260,373 2,116,182
11,953 1,500
1908
1,878,175 2,298,785 2,646,246 2,832,395 2,796,104 2,901,898 3,082,002 3,894,125 3,660,550 3,664,164 3,249,385 2,920,492 1,788,793 2,167,443 2,241,100 1,734,133 2,706,508 2,338,101 2,167,275 1,922,714 2,236,922 1,601,861 1,840,191 1,549,073 1,307,760 1,945,261
13 '39
1881
1882
1909
1910--.
16,701 20,916 28 899
1883
1911
1912
1884
2,000
3,700
6,136
2,069
3,500
6,398
9,357
13,895
8,008
5,230
280
1,089
3,767
3,477
1,742
6,902
14,915
7,444
2,686
4,336
4,055
17,930
14,579
13,515
32,037 18,097 17 032
1885
1886 -
1913
1914--.
1887--.
1888
1915
1916
1917
1918--
20,409 18,705 21,358 29,590 33,254 19,780 35,460 32,287 15,153 18,251 16,123
1889
1890.--
1891
1892
1893
1894- .
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933- _-.
Total values
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
13,422 11,319 14,317 9,392 7,100 4,783 3,865 6,471
1110,529,806
$638,323
Alpine ("Wheeler) prospect adjoins the Plymouth on the north, the shaft being only about 300 ft. north of the north end line of the Empire. This claim was opened in the 1860 's and the stock was traded in at San Francisco in the earlj^ 1870 's, when there was a 10-stamp mill on the claim. After a depth of 400 ft, had been reached and $78,000 had been paid in assessments with no dividends, work was stopped. A few thousand dollars was produced in 1895, after which the claim was idle until 1910. The deeper shaft was subsequently sunk to 600 ft. on an incline of 55°, the deeper levels being at 500 and 600 ft. There was also another shaft, 200 ft. deep. No important orebody was found and work stopped in 1914.
The Mariposa slate on this claim is cut by the Alpine greenstone dike, which here dips about 52° SE. and strikes nearly NE. The shaft struck this dike at a depth of about 200 ft. and followed the green- stone on its hanging-wall side to the bottom. A vein called the Alpine was found at this contact and followed on a curving course 700 to 800 ft. northeast. It may be a spur of the Empire vein. At a point 80 ft. west of the shaft on the 500-ft. level, the Alpine vein joins and is terminated by a vein striking north, persumably the Empire vein, on which considerable prospecting was done.
60 AMADOR COUNTY
The greenstone-slate contact is near the Plymouth end-line on the 600-ft. level.
Amador Gold (Aetna) is 1^ miles south of Jackson. Most of the work was done before 1900. A wide vein of quartz occurs at the contact of Mariposa slate (footwall) and amphibolite schist (hanging wall). An inclined shaft was sunk 700 ft. by 1890. Levels were turned at 350, 450, 550 and 650 ft. and some stoping was done, but production was evidently small, that of record amounting to only a few hundred dollars. At least 750 ft. had been drifted by 1890 on the 550-ft. level.
There was a 60-stamp mill on the Aetna.
The Moore Mine lies a little west, and when it was last worked the Aetna vein, or one so named, was prospected. (See Moore.)
Amador Queen No. 1, two miles south of Jackson, was extensively prospected between 1890 and 1901 by Jackson Gold Fields and Jackson Exploration and Development Company. The only recorded production was a few hundred dollars a year during the above period from rock taken out in the course of prospecting.
The shaft was sunk 1250 ft. on an incline of about 65° on the contact zone, with amphibolite schist hanging wall and slate footwall, there being first Calaveras rocks, and farther west Mariposa slate on the footwall side. Hunts Gulch is believed to be the surface expression of a strike fault. Drifts were run north 500 ft. or more on the 400-, 500-, and 800-ft. levels, and drifting was also carried south on these levels for an unknown length. A west crosscut was also run 250 ft. on 500-ft. level, where a vein 28^ ft. wide was reported, but too low grade there to pay. The workings were said to be nearly all in amphib- olite schist, closely folded and twisted, and with many seams and lenses of quartz. Average grade must have been quite low.
Amador Queen No. 2 is two miles south of Jackson on the narrow band of Mariposa slate called locally the 'black metal belt.' The Valparaiso and Mammoth mines are similar geologically, lying on the same belt, all three being known as producers of 'specimen' ore with arsenopyrite.
The Amador Queen No. 2 was opened by a crosscut adit 1200 ft. long which reached the slate-greenstone contact. From here a drift was run 1000 ft. south and 460 ft, north. An internal shaft was also sunk 900 ft. on the dip of the slate, 62° E., giving a total inclined depth of 1212 ft. Levels were run at 500 and 700 ft. in depth in the shaft. In late years, however, the shaft has been under water and the work at time of last visit was in a raise near the end of the south drift on the adit level. This mine has been worked every year in a small way since 1918; before that, operation appears to have been irregular,* although the greater part of the underground workings had been run by 1900. The production reported in late years has been mainly from high grade and often from 'specimen' ore and has averaged a few thousand dollars a year.
The interlayered schist and slate seen in the accessible workings showed no pronounced fissures or gouges. The formation being mined at the time near the south end of the workings was a very hard, blocky, siliceous schist. The band said to carry gold there was a strip of slate
MOTHER LODE GOLD BELT 61
about 4 ft. wide, containing gold-bearing stringers of white quartz which terminate at the walls of their immediate slate band. The gold occurs with arsenopyrite and the concentrate sometini,es is worth several hundred dollars a ton, although occurring in only small quantity.
Amador Star (Rhetta) Mine, 3 miles north of Plymouth, covers 130 acres (agricultural patent) in Sec. 23, T. 8 N., R. 10 E. Previous to 1900, it had been worked through a shallow crosscut adit, which struck the vein 422 ft. from the portal, going nearly due west ; thence running south 37 ft. and south of southwest 137 ft. Some ore was mined about this adit (to a depth of 100 ft.) and crushed at the Bay State mill; the amount and value are not known as the two were worked by the same company. Two veins were reported ; one at the contact of Mariposa slate hanging wall and greenstone (altered diabase) footwall, and the other branching from it and running nearer north in the slate. The mine map, however, shows only one, although Storms reported that "Both of these veins have been explored with satis- factory results."
After the adit mentioned was driven, a vertical shaft was sunk about 1917 to a depth of 580 ft. with one level at 500 ft. from which a crosscut was driven 150 ft. to the greenstone and slate contact. Along this a drift was run 470 ft. north and 150 ft. south, following a small vein which gave low assays. These workings did not connect with the old adit, although the north drift runs almost 100 ft. beyond the old adit. Several crosscuts were run west to the greenstone on the 500-ft. level without finding ore.
The assays on the adit level indicated that a length of a little over 100 ft. showed promise of producing ore below. The fact that the downward extension of this ore was not encountered on the 500-ft. level raises a question as to whether the ore passed into a fissure in the slate, or raked away from the lower workings. In 1931 Amador Star Mining Company began work from the 300-ft. point in the shaft and reported striking a promising prospect 225 ft. west. On account of lack of funds, water had been allowed to rise again above this point at time of visit, so it could not be seen.
Since the above was written, the property was leased with option to purchase to Arthur Hamburger, who did considerable work under the title of Hamburger ]\Iines. This included a crosscut run about 1000 ft. eastward on the 500-ft. level in search of a hanging-wall vein. No such vein was found, the rocks penetrated consisting of Calaveras schists with the interbedded igneous rock showing flow structure in places, which is occasionally seen in this formation. Some work was also done on the 300-ft. level which was 670 ft. long early in 1933 ; and on 500-ft. level, mostly clearing old workings or running new ones parallel to the old. A mill was erected using the flotation system (see under Metallurgy). Hamburger later formed the West American Consolidated Gold Mines and about 40 men were employed when the place was visited June 15, 1934. Work in the levels had been stopped pending the sinking of the .shaft to a depth of 900 ft. The mill was also to be closed temporarily.
The vein on the 500-ft. level is reached by a crosscut 150 ft. north. On this level former operators had drifted ,150 ft. south and 750 ft.
62 AMADOR COUNTY
north. The present company ran a drift parallel to the old one on the south, and are reopening the old north drift. In the south drift, two raises for stopes have been started. The vein in the face shows 2^ ft. of quartz, a small fault there showing the upper segment thrown its \\idth horizontally eastward and onlj^ about one foot vertically down- ward. Elsewhere it shows greater width, increasing northward to a maximum of 8 to 9 ft. in a distance of 400 ft. Where it has this width, it consists of a strand of quartz on each wall separated by several feet of slate and quartz stringers with considerable pyrite. The superin- tendent claims heads worth about $6 a ton from the small amount of rock milled.
Anita or Bright Mine is one-half mile southwest of Jackson. The surface was worked in early days, but no depth was reached until Anita Gold Mining Company began sinking in 1895. They sank an inclined shaft at an angle of 63° in and near the contact of the footwall green- stone and the narrow strip of Mariposa slate which extends south from the Argonaut Mine and carries the western branch of the Mother Lode. The shaft was started in slate but at 125 ft. struck the altered green- stone. At the 500-ft. level it required a crosscut 75 ft. long to the vein, and below there was in very hard greenstone.
Levels were run but details of these are lacking except for the one at 500 ft. Here, after the crosscut was run, drifts were extended north and south a total length of 700 ft. An ore-shoot 114 ft. long was claimed by the promoters on that level, but on account of a heavy flow of water encountered there, the level was closed by bulklieading and the shaft was continued to a depth of 770 ft., where work appears to have stopped, without any record of production.
Argonaut Mine History
Originally known as the Pioneer, this mine was first worked in 1850, but received little attention for many years; in 1876 the depth reached was only 150 ft. and there was no mill, although the adjoining Kennedy workings had been brought up to the property line, where the Pioneer ore-shoot was known to be 18 ft. wide. Most of the early work on the Pioneer was through an adit on the northern end of the claim. Argonaut Mining Company was incorporated in 1893. Oper- ation has been continuous since except for interruptions caused by fires. In the sping of 1919, one started which was not brought under complete control until the lower workings of the Kennedy and Argo- naut had been flooded. This caused a loss of a year's time. Again, on August 27, 1922, a fire from some unexplained cause began near the 3350-ft. level and caused the loss of 47 lives on the 4650- and 4800-ft. levels. Milling of ore was interrupted again for about a year at that time.
Production
The total production reported by Argonaut Mining Company has been about $19,000,000. The tonnage of ore handled yearly since 1910 (except for 1920, 1921 and 1923) has been from 62,000 to 91,000 tons.
MOTHER LODE GOLD BELT 63
The best section of the mine was between the 3400-ft. and 4800-ft. levels, where mining between 1914 and 1920 yielded ore which averaged from $10 to $13 a ton. The average value both before and since that period has been lower; a total of 914,466 tons of ore yielded $7,702,705 between 1913 and 1926. The production until 1932 has been entirely from the Pioneer claim. Dividends paid have exceeded $3,000,000.
Geology
The geology of the upper one-third of the mine has been described in past publications of both the State Mining Bureau and U. S. Geo- logical Survey, which both stated that the vein occupied a fissure apparently opened by a reverse fault in which the hanging wall had been thrust up about 125 feet as indicated by displacement of the Mariposa slate in the raise from the 470-ft. level to the old Pioneer adit. Here should be mentioned the argument of Kennedy Extension Mining Company in their suit with the Argonaut Mining Company. About 1200 ft. in depth on the Argonaut fissure, a vein branched into the hanging wall. The former company contended that this was the older vein, which had been displaced about 700 ft. by normal faulting as measured along the Argonaut fissure. The plaintiffs lost this suit.
The upper part of the vein to a depth of 290 ft. is in altered green- stone, which has been classified variously as diabase, meta-andesite and augite-melaphyre tuffs and breccias. Near the vein the greenstone has been rendered schistose, and is locally termed amphibolite schist, a term sanctioned not only by local usage but by geologists. Knopf prefers to accent the changes in the greenstone due to hydrothermal alteration, and points out that it is merely a facies of the greenstone. He found much ankerite in it. From 290 ft. to about the 470-ft. level, the vein traversed a narrow belt of Mariposa slate, and from there to 2500 ft. deep was on or near the contact with Mariposa slate footwall and the schistose altered-greenstone hanging wall. From there downward for the most part the footwall country rock is hard gray schist, but with a casing of black slate between it and the vein, and the hanging wall is Mariposa slate. Where seen on the 4800-ft. level the slate casing on the footwall was 10 ft. thick but in places is from 20 ft. to 40 ft. thick, varying with the weaving courses of the footwall contact and the strike of the vein. On the 4350-ft. level the vein strikes N. 18° W. and dips 63° northeast, with slips in both the walls about parallel to the strike of the vein, but those in the hanging-wall slate dipping about 80° northeast. On the 4500-ft. level the footwall con- tact strikes N. 20° W. and dips northeast 60° to 63°. On the 4800-ft. level the shaft crosscut to the vein crosses a pronounced slip with hard, blocky gray schist on the hanging-wall side and slate on the footwall. This slip is 125 ft. east of the true footwall, strikes N. 30° W. and dips 75° northeast. The vein, close to the footwall, has the normal strike of about N, 18° W. and dips 60° northeast. To properly correlate the geology of the Argonaut and the neighboring Kennedy on the north, it should be remembered that the Argonaut has the main footwall vein only, while in the Kennedy the breaking away of an immense horse of rock led to the formation of a hanging-wall vein also. Sills of greenstone, now standing nearly vertical, and entirely altered to schist,
64
AMADOR COUNTY
MOTHER LODE GOLD BELT 65
occur within the Mariposa slate and on certain levels, as a result, the immediate hanging wall is greenstone and the footwall slate, as on the 3700-ft. level.
On that level the fissure was seven to ten feet wide and was one- half filled with gouge and half with quartz. Between the 3600- and 4200-ft. levels, because of its north pitch, the north ore-shoot was in the Kennedy, then returned to the Argonaut. On the 4200-ft. level the vein was 20 feet wide ; on the 4350-ft. level it was 30 feet wide, and continued wide in the south drifts in the deeper levels. Though most of the earth movements have resulted in crushing the slate, the footwall schist is in places shattered, and traversed by numerous quartz veinlets and occa- sional slips about parallel to the main vein, the schist being reduced nearly to gouge along these slips. The complete tracing out of the faults in this or any of the other large mines on the lode would require careful study at frequent periods over a number of years as the development work went on. Besides the pre-mineral strike fault of the lode, and the accompanying slips, there have been important oblique faults in the Argonaut property, and post-mineral faulting within the vein. The 4500-ft. north drift 150 ft. south of the Kennedy line showed the vein 15 ft. wide with a width of six ft. next the hanging wall dragged down. On the south on many levels the ore had been considered as bounded by an oblique fault. This strikes northwest and its trace on the plane of the vein dips 70° to 75° northeast, judging from the positions where it was encountered on many levels. On the 4500-ft. level, about 200 ft. south of the shaft crosscut, there was a length of about 200 ft. of broken and crushed ground as a result of this fault. On the 4650-ft. level, the vein was stoped 480 ft. in length when the crushed ground was encountered. This extended for 75 ft., and ore was found south of it, showing, when visited, 25 ft. of quartz of which the hanging-wall part was solid white quartz, with the best ore consisting of a few feet of ribbon rock on the footwall side. On the 4800-ft. level the vein widened rapidly south of the region where the fault had been found on the levels above. From a width of a few feet on the north, the vein increased in width to 60 ft. on the south, and there was stoped 30 to 60 ft. wide. The stope length on this level was over 1000 ft. On the 4950- and 5100-ft. levels the vein is reported much narrower, and the ore-shoot has apparently shortened and become flatter, approaching the shaft, which is in the hanging wall of the vein. The manager reported also a lower average grade of ore and ground increasingly hard to hold open, resulting in an operating loss in 1926. The ore conditions did not improve materially again until the 5550-ft. level. Here a junction of two veins gave a large, low-grade quartz body on the north. Some ore was found on the south, however, this being the top of a new ore- body. On the 5700-ft. level, the north drift showed ore from 6 to 17 ft. wide for a length of 200 ft. up to the Kennedy line. In the south drift on this level, three ore-shoots, 158 ft., 235 ft., and 170 ft. long respec- tively, varying from 5 ft. to 12 ft. in width and from $3 to $12 a ton in value, were found, the last still showing in the face. At the time of \dsit in 1932 the 5800-ft. level had been opened for 1100 ft. and the ore being mined from day to day from both drifts showed many vari- ations, but held up well in value on the north shoot.
^~"*^^^ PHYSICAL SCIENCES LIBRARY
UNIVERSITY OF CALIFORNIA DAVIS, CAUFORNIA 95616
66 AMADOR COUNTY
The recent work in the Argonaut has given such encouraging results that at the middle of 1934 the operators were optimistic about the future and were planning prospecting work to determine the pos- sibility that hitherto unsuspected ore reserves might exist in the unde- veloped section above the present bottom.
The winze from the 5500-ft. level, 300 ft. south of the shaft, has been deepened and levels have been opened at 5500, 5700, 5800 and 6000 ft. inclined depth. Late in June, the 6000-ft. level had been drifted 950 ft. and the 5800-ft. level 600 ft.
The upper ore-shoot, which had been the mainstay of the mine for so long, split into two branches near the 5400-ft. level, and these were worked separately below there. The southerly limit of this ore on the 5700-ft. level was 500 ft. south of the winze. From there the south drift was advanced on the footwall side, and at 250 ft. a crosscut was run toward the vein, entering a section of faulted ground carrying some good ore in the drag. The fault conditions at that time were not understood. Later work brought out the fact that this crosscut was in what is now called No. 3 fault, the southernmost of three such so far discovered. No. 1 fault had been known since the early history of the mine, and had generally been regarded as a boundary for ore. This fault had a horizontal throw at the most of 80 ft. on the 2880- and 3000-ft. levels, and has persisted with depth. No. 2 fault, south of No. 1, was found to have a horizontal throw of 50 ft., or 80 ft. on the drag on the 5700-ft. level, and No. 3, which is 200 ft. south of No. 2, has about the same horizontal throw of 50 ft. Each of these faults have moved the vein segments east, looking south. In June the company reported 200 ft. in length of ore between No. 2 and No. 3 faults, and 200 ft. between No. 3 fault and the south face, where the vein was 9 ft. wide. In this drift the vein was reported from 9 to 16 ft. wide. The grade of ore in this shoot so far is reported about the minimum that could have been worked at the old price of gold, i.e., $6 to $7 a ton.
On the 6000-ft. level, the assays in the region of the old ore-shoot are low-grade, but in a raise which was 40 ft. above this level in June, 1934, some very good ore was being found. This was 9 ft. wide and shows strands of heavy sulphide (pyrite and galena chiefly), suffi- cient to raise the sulphide content far above average. Ore recently has been coming from levels between 5500 and 6000 ft.
A crew of 225 men in all was employed in 1934 up to the time of the strike, October 2. About 180 of these were working underground. The mill has been crushing 8000 tons a month. There does not appear to be much change in the character of ore at this depth except as noted on the 6000-ft. level. About 150 tons of sulphide concentrate is pro- duced monthly. Both walls in the bottom are still reported to be Mari- posa slate.
A storage battery locomotive, hauling six 1-ton cars, has been put in use lately on the 5500-ft. level between the winze and main shaft. An Eimco mucking machine (the first used in a Mother Lode quartz mine) has also been installed and has been operated chiefly in drifting on the 6000-ft. level.
MOTHER LODE GOLD BELT 67
Ore
The ore is generally best within a few feet of the footwall where it is of a ribboned structure which indicates repeated reopening move- ments and filling along that wall. Specimen rock is found at times. Some of the ore in the south shoot which had the appearance of massive, barren quartz gave surprisingly high assays. The ore has of course considerable admixed black slate as it goes to the niill, but due to the width of the quartz vein in this mine the proportion is less than in many cases where stringer leads are mined. Ore has remained free milling to the great depth reached, in the sense that most of the gold is released by proper crushing and can be saved by amalgamation. In 1931, when 61% of ore came from the 5700-ft. level and 32% from the 5550-ft. level, the concentrate formed 2.4% of ore milled, and yielded 22% of the gold saved and 28% of silver. The gold content of concentrates has ranged from 2.6 oz. to 5 oz. per ton, varying with the grade of ore. As the grade of ore decreases the amount of silver in the concentrate, never important, appears to increase to about 1 oz. per ton, possibly due to a little higher proportion of silver in the sulphides of the wall rock, of which more is likely to be milled when the vein narrows. Pyrite is by far the most plentiful sulphide. Galena is always favorably regarded, as is also arsenopyrite, Pyr- rhotite, chalcopyrite and tetrahedrite also occur sparingly. Three periods of sulphide mineralization are noted; 'paint' sulphide, which is worthless, another with a glossy look, is low grade. Over a long period, there is no such thing as an average grade ore in these Mother Lode mines. The paper average of $8.42 a ton for the Argonaut between 1913 and 1926 on a total of nearly a million tons conceals variations of several dollars a ton. As noted, ante, under Production, the best ore found in large quantity, was between the 3400-ft. and 4800-ft. levels and averaged $10 to $13 a ton.
Mining Conditions and Methods
The inclined shaft of the Argonaut has three compartments, one for manway, pipes, etc., and two for hoisting, each being 4 ft. 1 in. by 5 ft. 9 in. in the clear. Dip of the shaft is 63° to the 1650-ft. level. The vein was flat for the first few hundred feet from the surface and there lies under the shaft which crosses it at the 290-ft. level. From the 470-ft. level downward, however, the vein steepened so that the shaft crossed it again at 1650 ft. and below there is in the hanging wall. From 1650 ft. to 4050 ft. the shaft has an inclination of 57°, then steepens again to 63°, so that it remains at about a constant dis- tance from vein in the deeper levels; the crosscuts from shaft to vein are 215 ft. long on the 4950-ft. and 5250-ft. levels. The nature of formations required heavy shaft timbering and 'Oregon pine' (fir) 20 by 20 inches was used for most of it, but lately somewhat smaller sizes have been thought sufficient, where the ground is not hea^^ or broken. This shaft is 5700 ft. inclined depth. On the 5550-ft. level, 225 ft. south of the main shaft and in the footwall, a station was cut, another hoist installed and sinking was resumed, with the 6200-ft. level as an early objective, although the hoist will permit going much deeper if desired. Levels are 150 ft. aparL
68 AMADOR COUNTY
The ground is heavy, particularly along the vein, so that very little space can be left open while stoping. Parts of shaft crosscuts in hard schist are the only exceptions to the heavy timbering which forms one of the principal items of mining expense. Drifts to prospect the vein and prepare for stoping are usually run one set wide along the foot- wall with a pillar left along the hanging wall, which is later taken from the next lower level. Posts of drift sets are of local round pine, from 12 to 24 inches in diameter and caps are 12 in. by 12 in. Posts are spread to withstand side pressure. In lagging, space is left to permit gouge and fine rock to squeeze out and relieve pressure. Modified square-setting with waste filling was standard practice until 1925- 1927 when a form of vertical slicing was tried. This had to be abandoned and the old method resumed. In these square sets round posts 14 in. to 18 in. in diameter, caps 12 in. by 12 in. and girts from 8 in. to 12 in. are used. Waste filling taken from chambers in the walls is kept up to within one set of the stoping work. Even with this, the ground will soon begin to squeeze. The heavy ground discourages much advance development, and induces as rapid stoping as possible, once a block is opened. These ore blocks are generally worked in sections about 100 ft. in length above the drift at a time, with ore chutes 25 ft. apart.
Ore is drilled with 1-inch stopers, blasted with 30% gelatin dyna- mite, and hand trammed to shaft ore-pockets in 1-ton cars. Skips running in the main shaft are operated in balance so far as possible, by a geared hoist having drums 8 ft. by 47 inches using wire rope 1^ in. in diameter, and made of 6 strands of 19 wires each of crucible steel with a hemp center. Power is furnished by a 500 h.p. 60-cycle, 8-phase induction motor, operating at 440 volts, with a master switch and liquid rheostat. Though the hoist is of 72 cubic feet capacity, the average load of ore hoisted in 1931 was 7464 pounds.
Milling Methods, Recovery
Ore generally, because of its friable nature and the blasting practice, reaches the surface grizzley rather fine ; oversize plus 2^-inch, is broken in a jaw crusher in the headframe, is weighed and taken to the mill bins by a tramway. These bins hold 2200 tons. Ore is fed by Challenge feeders to the 60 stamps, weighing 1285 lb. each newly shod. Battery screens are of No. 30 brass wire with openings of 0.0277 inch. Stamps drop 8 inches 96 times a minute, and discharge averages 7 inches high. These stamps were made in 1916 by Knight & Com- pany of Sutter Creek. An 85 h.p., 60-cycle, 440-volt induction motor is used for each 20 stamps.
Some years ago (1922-1928) this company installed Dorr classi- fiers, Deister and Wilfley concentrators, cones and tube mills for regrinding. Lately they have taken all this equipment out of use and have returned to the simpler flow sheet. After inside and outside amalgamation, pulp passes to spitzlutte, one for each 5 stamps, and each of these deliver different sized products to each of two improved iron-frame Allis Chalmers vanners. Overflow from spitzlutte goes to a Callow cone from which underflow passes to a third vanner ; three vanners thus handling the product of each 5 stamps. Vanner tailing
MOTHER LODE GOLD BELT 69
and overflow from cones pass through a pipe to the cyanide plant of Amador Metals Reduction Company. Vanners require about 1 h.p. each. Concentrate is shipped for smelting. In the long run over a period of many years, the mill extraction under the method described does not appear to have varied materially from the more elaborate one using tube mills, late model concentrators, etc. Recovery in the mill has ranged from below 84% to 91%. Both of these extremes were had when using the tube mills. When using vanners, the average extraction was from over 85% to 89%. Metallurgists are prone to account for this condition by assuming that foremen and millmen accustomed to nothing but vanners cannot or will not get maximum results with machinery which requires more attention and greater skill. But the difficulty is also largely due to the association of most of the gold lost with carbonaceous slimes. In the cyanide plant of Amador Metals Reduction Company the sand and slime are first separated in a Dorr classifier, and are separately cyanided, as described in more detail in the chapter on Metallurgy.
Costs for 1931 Mining cost, per ton mined (operating costs) :
Item Amoutit
Mining $1,913
Development 1.033
Hoisting .511
Surface .448
Repairs, maintenance .859
Total $4,764
Distribution of mining costs (operating) :
Atnount, per ton Account mined
Labor $3,307
Timber .353
Power and water .336
Explosives .139
Hardware and supplies .437
Insurance .015
Accidents .111
Freight, etc. .066
Total $4,764
70 AMADOR COUNTY
Distribution of milling costs :
Amount, per ton Account milled
Power, water, lights $0,196
Labor .266
Treatment of concentrate .349
Hauling .024
Hardware and supplies .081
Insurance .015
All other expense .026
Total $0,957
Recapitulation :
Mining cost, operating $4,764
Milling cost, operating .957
General .488
Total $6,209
Ballard Mine (Ballard and Martin). Mrs. Maria Ballard, owner. Leased to John F. Ratto with option to purchase. Comprises E^ of AV^ of Sec. 14, T. 8 N., R. 10 E., containing 160 acres under agricul- tural patent.
Although considerable work was done in early days here, including the sinking of several shafts and some stoping there is no available record of results. In 1928, Lopez Mining Company put a 10-stamp mill at the main shaft and reopened that shaft and the 200-ft. level, extending the latter south. They failed and the property lay idle until late in 1932, except for some shallow work by lessees. Early in February, 1933, about 10 men were employed. The south drift on the 200-ft. level was then 175 ft. long and being extended ; on the north, an old drift had been reopened on the same level for 80 ft.
The west vein is reached by a crosscut 430 ft. long from the shaft on the 200-ft. level. The workings are in Mariposa slate. An ore shoot about 50 ft. long is claimed in the south drift, near the crosscut. It has not been explored except on this level, so far as known. Farther south, the drift was turned away from the apparent course of the vein, as indicated by holes lately put in the west side of the drift. The quartz so revealed is to be prospected. The Spanish shaft is 70 ft. deep and is about 150 ft. ahead of the south face ; and some large out- crops of quartz could be prospected at depth by running this level 350 ft. south. On the north, 500 ft. from the shaft crosscut, an old adit cut a vein 16 ft. wide which is said to offer inducements to carry the north drift ahead on the 200-ft. level to prospect it.
A light 5-stamp mill with one concentrator was being completed at time of visit, on a hillside 600 ft. south of the main shaft, and above it. This will permit mill tests of quartz from nearby outcrops and from old shafts sunk years ago. At main shaft there is a portable compressor, two 4-cylinder gasoline engines and a single drum hoist.
Early in 1934, a decision in favor of Ratto was rendered in a quiet title action against H. L. Berkej' and Ballard-Plymouth Gold Mines Co.
MOTHER LODE GOLD BELT 71
Bay State Mine, four miles north of Plymouth, was opened in the early 1890 's, the shaft having been 300 ft. deep in 1892. Water was struck in such quantity that the drifts on the 300-ft. level were closed with concrete bulkheads in 1893, and shaft-sinking was continued. A 10-stamp mill was erected and early in 1895 was running steadily on ore stoped between the 600-ft. and 500-ft. levels. Late that year ore was being mined from four places on those levels and was said to be pajang a little more than expenses. This ore was stoped from the 600-ft. to 400-ft. level by Bay State Mining Company. The total reported production from 1892 to 1897, inclusive, was about $34,000. This company quit work at 750 ft. in depth about July, 1897. Work was resumed in 1899 but no more production was made until 1900 when Globe Mining and Milling Company took control. From then until 1905 production was small and irregular, amounting to about $24,000 in all. The main shaft reached a depth of 1065 ft. on an incline of 81°. and was 44^ ft. bv 9 ft. in the clear. Levels were run at 300, 400, 500, 600, 750," 830 and 1030 ft. The last production was in 1909 but the exact amount is unknown as it was worked in connection with the Rhetta.
The shaft was sunk between the West and Middle veins, and the principal work was on the latter, also called the Bay State vein. The Kretcher or West vein was reported to have been reached by a crosscut 350 ft. long from the 300-ft. level, and by longer crosscuts on the 750-ft. and 1030-ft. levels. The Bay State vein was opened for a length of about 300 ft. on each side of the shaft on the 1030-ft. level, and Kretcher vein was prospected for a length of 200 ft. in each direc- tion on 750-ft. level, also 250 ft. north and 300 ft. south on 1030-ft. level. If any ore was stoped from the latter, there is no separate record of it at hand. It is stated that a raise was run from the 1030-ft. to 700-ft. level on this vein. The veins are said to average 4 ft. thick but in places reach 12 ft. in thickness. It has been stated that work in 1899 on the C. Kretcher property south of the Bay State indi- cated that these two veins join there. The strike of main vein is N. 15° W. and dip'76° E.
There is also stated to be an east vein, called the Vaughn, which was struck in a crosscut from the bottom level, but water caused trouble at this face also. Definite details are lacking, but considerable low- grade rock is claimed to exist in the mine.
There is no equipment on the property. It is on an agricultural patent.
Late in 1934, this mine was being unwatered by AVest American Consolidated Gold Mines.
Bellwether Mine, one-half mile north of Jackson on an agricultural patent 600 feet by 3200 feet on the East (or Zeila) vein, was developed by Bellwether Mining Company between 1895 and 1900. Previously it had been prospected by several shallow shafts, the deepest 180 feet deep. The later work included an inclined shaft 320 feet deep with crosscuts and drifts to prospect the wide vein, which is the east or hanging-wall branch of the Mother Lode, carrying ore similar to the Zeila Mine, on the south. On the 282-ft. level, a crosscut was run east 130 feet, and it was claimed the lode was found to be 85 feet wide and was reported to show fairly good assays for a width of 40 feet. Noth-
72 AMADOR COUNTY
ing more is known of the claim, which later w'as bought by the Ken- nedy Mining and Milling Company.
Bunker Hill Mine {South Mayflower) History and Production
Originally called the Ranchoree or Rancheria Mine, under which name work started in 1853, the Bunker Hill claim was first worked by open cut, then opened through the south shaft, 350 ft. from the Little Amador line. In 1863, Bunker Hill Quartz Mining Company was organized and the south shaft was sunk to 450 ft. on the incline in the next few years. Later the north shaft was started 360 ft. from the first and both were in use many years. Soon after the beginning of work a 12-stamp mill had been built. The ore in the upper workings was often rich, as between the 170-ft. and 270-ft. levels, where it is said to have yielded $50 to $75 a ton. Most of the ore came from the vein in slate, although a drift on the hanging-wall vein in greenstone is said to have yielded in one place "$2,000 in gold for every barrel full." At 350 ft. the vein was reported 6 ft. wide and yielded $10 a ton with a working cost of $7 a ton. A 40-stamp mill and a chlorina- tion plant were built in 1880, and the next 10 years were devoted to working out the ore in the Mariposa slate. By 1888, the north shaft reached a depth of 800 ft. on the incline (680 ft. vertical). The mill was crushing an average of 99 tons a day. Mining cost $3.35 a ton, milling 60 cents and chlorination treatment of sulphides (then 2% of ore) $14.61 a ton. Knopfs quotes Elisha Hampton, former Super- intendent, as saying the mine produced $1,272,000 prior to 1891. In that year only $7,386 was taken out.
By 1893, the mine had been idle long enough to permit the main shaft to cave and the plant to deteriorate. It was re-named the South Mayflower and a reopening was begun, the Mayflower and Nevada, claims being consolidated with it about this time. In 1894 the group produced $30,000 and in 1895 a claim on the hanging-wall greenstone known as the East Mayflower yielded $5,000. In 1899, Bunker Hill Consolidated Mining Company was organized and worked steadily until late in 1922.
At 800 ft. in depth, the principal channel of mineralization entered the greenstone and the larger part of ore thereafter was 'grey ore,' entirely different from and much lower in average gold content than the slate-quartz ore mined above. During this period, 887,585 tons of ore yielded $3,834,550. The last production amounted to $5,446 in 1925. This gives a grand total of $5,154,382. During 11 years prior to Sep- tember, 1916, this mine paid 123 dividends, said to have amounted to about $1,000,000 or about 5 times the amount of the capital stock ($200,000 par value). Assessments were levied after 1916 but their amount is unknown. Profit stopped with ore at $4 a ton.
Mine "Workings and Geology
The most profitable operations at this mine, as at most of those on the lode, were on orebodies in the black Mariposa slate at the metande- site contact, known here as the hanging-wall vein or Bunker Hill Vein.
lU. S. Geol. Survey, P. P. 157, p. 55.
MOTHER LODE GOLD BELT 73
The footwall of this vein was usually the soft, swelling slate, and hang- ing-wall greenstone (meta-andesite) although the wall rocks were in places both slate, or the footwall greenstone, due to the vein crossing interlayered bands of slate and greenstone. The work between the 1950-ft. and 2800-ft. levels is on the hanging-wall vein, and this same vein was being prospected in the winze workings below 2800 ft., where the hanging wall is hard meta-andesite, in places altered to schist. The ore in this vein is a black gouge ore with quartz stringers. This vein Avas stoped above the 2400-ft. level, where the orebody was of a max- imum length of 800 ft. and a maximum width of 10 ft., averaging five to six feet. There is still considerable low-grade ore left above the 2800-ft. level.
The upper slate orebody, as noted above, had been worked out by 1891 down to the 800-ft. level. The 'grey ore' body was first found on the 1400-ft. level and was worked for a length of 420 ft. there, extending 280 ft. south of shaft. Where first found it was 40 ft. west of and about parallel to the Bunker Hill vein. The ore lenses occupied a wedge-shaped section, entering the hanging-wall vein on the north. It had a maximum length of 850 ft. and average width of 30 ft. but was in places 125 ft. wide. It was worked down to the 1950-ft. level. This 'grey ore' was formed by the hydrotliermal alteration of the greenstone. It contained up to 4% of sulphides principally pyrite. It furnished the bulk of profitable tonnage during the last company's operations.
Most of the later work was north of the shaft, and below the 1950-ft. level on the hanging-wall vein. . This vein here is a crushed gouge of slate and quartz stringers with some large bodies of low-grade massive quartz. In the 2200-ft. level north drift there was a width of 30 ft. of barren quartz on the hanging wall, with 4 ft. of ore on the footwall, the two sections being separated bv a gouge seam. From the 1950-ft. level to 2800-ft. level, lengths of from 1450 ft. to 1778 ft. (by co-ordinates) were drifted northward on the hanging- wall vein, all the later operations having been devoted to a search for more high- grade ore in it. At the time of last visit the 3200-ft. level had been run 100 ft. each way and the 3400-ft. level 350 ft. north and 100 ft. south on the same vein. It was found to vary from a few inches to over 30 ft. in width. Near the shaft this gouge of slate and quartz occupies what may be a spur in the footwall of the main Bunker Hill or hanging-wall vein, the junction of the two being 860 ft. north of the shaft. The large 'grey ore' body occupied the wedge between them. The hanging-wall vein .showed a length of 800 ft. and an average width of 5 to 6 ft. of material where opened on the 2400 ft. level, but the assays generally on this vein between the 800-ft. and 2800-ft. levels were too low to make ore, and much of it was left unstoped.
Ore and Concentrate
About two-thirds of the gold saved from ore and "near ore" mined in later years, was from concentrate. Over a period of several years the concentrate averaged 3.14% of ore and yielded an average of $77 a ton. The recovery was 80% to 82% before a ball mill was added to regrind sand tailing. This was used only about 2 years. For some years a cyanide plant was operated on tailing, but the saving with this went as low as 25 cents a ton.
74 AMADOR COUNTY
Mining and Milling
On the Bunker Hill vein square-set timbering was used with filling. Timbering cost 30 cents a ton. On the 'grey ore bodies' the shrink- age system of mining was followed, using some stulls and butt caps. The average production of ore per man-shift for underground workers was 1| tons and for the entire crew about 1^ tons during years of full operation. The total operating cost then was $3.34 a ton, of which $1.66 was for mining, 25 cents for treatment and 45 cents for development.
There was a 150-gallon electrically driven pump on the 800-ft. level, one of 50 gallons capacity on the 2100-ft. level and an air driven pump on the 2400-ft. level. About 50 skips of water a week was hoisted from the bottom of the shaft (2800 ft.) and about 10 skips a day from the winze (3440 ft.).
Ore was hoisted in 2|-ton skips by a double-drum hoist with 300-h.p. motor. The reduction plant had a simple flow sheet, equip- ment having been as follows : Knight crusher, forty 1050-lb. stamps, 24 vanners, 5 other concentrators, and 5 ft. by 6 ft. Hendy ball mill. Milling practice when at full capacity in 1915-1916 included stamping and amalgamation, followed by concentration on Deister tables after which the sands were ground in the Hendy mill and the entire pulp was concentrated on the Frue vanners.
Centennial claim is in W^ of SWi Sec. 13, T. 7 N., R. 10 E., a little east of the Dry Creek claim of Detert Group. The vein is in the altered greenstone of the hanging wall of the Mother Lode. An inclined shaft was sunk in 1900 to a depth of 630 ft. It passed into the footwall and crosscuts were run to the vein on the 150-, 250-, 350- and 630-ft. levels. Width of the vein is reported from 2 to 18 ft. There is no record of production.
Central Eureka Mine History and Production
Originally located as the Summit Mine in 1855, the claim yielded a 'chimney' of ore at a depth of 165 ft. which produced $30,000. Two shafts were carried down to depths of 550 and 700 ft. respectively, without any more production, and work had been stopped by 1875.
The mine lay idle thereafter until 1896 when Central Eureka Min- ing Company began operations. The later history has been highly interesting. The south shaft, which was 700 ft. deep when this com- pany started, was sunk to a depth of 2500 ft. by 1907. A 10-stamp mill was built in May, 1900, but production had started before this, some ore having been crushed at the Zeila mill. During this period, ended in 1907, the operations were on the hanging-wall vein between 1000-ft. and 2500-ft. levels, but a little ore was taken from the inter- mediate vein. Very good profit was realized from this section of the mine, but the best ore had been mined by 1907.
After closing down in that year, the mine was reopened in July, 1908, but for the next ten years results were discouraging. The extrac- tion dropped to an average below $4 a ton and many assessments were levied. The retiring directors in April, 1916, concluded the mine was exhausted, and wanted to quit. Conditions at the time appeared to
MOTHER LODE GOLD BELT 75
warrant this. The shaft had been sunk an additional 1000 ft. and for several years the ore-shoots had been shortening and of low grade. The plant was getting old and the shaft was in dangerous condition, with the skip still being run on strap iron. Due to the convergence of the end-lines in the direction of the dip, the length of the holdings along the contact vein was shortening on each successive level. All 3 veins had been mined and had proved disappointing. But although the 48th assessment had been levied, it was fortunate for all concerned that the new directors determined to continue.
Early in 1919, the 3500-ft. level was reached. The shaft crosscut on this level showed signs of ore. On the north, also, a good shoot was found and was stoped to the 3425-ft. level. In a winze below the 3500-ft. level a sub-level was turned and was run both ways in fine ore. Then followed a period of 11 fortunate years during which the shaft was carried to a depth of 4965 ft. on the incline and every year wit- nessed the payment of dividends. During this period the adjoining Old Eureka mine comprising the Amador, Maxwell, Alpha and Rail- road claims and 136 acres of adjoining land was bought and paid for ; a new steel head-frame was erected and many other replacements and improvements were made.
Below the 4500-ft. level the ground was found to be badly broken, and shaft and drift maintenance and other underground repairs cost more than breaking ore. These conditions, together with a lowering of gold content in the ore, led to a substantial operating loss during the calendar year of 1930. The lower workings of the Central Eureka were therefore abandoned and all pipe, rails, pumps, etc., were removed from the deeper levels and the track in the shaft below the 3900-ft. was taken up. This closed, at least for the time being, the productive history of the Central Eureka or Summit claim. Since then attention has been turned to the development of the Old Eureka section, sep- arately described under that name.
The production of the Central Eureka claim has been about as follows, including the year 1930:
From 1869-1871 $30,000 (ore $16 to $32 a ton)
From 1896-April, 1901 223,470 (tonnage not known)
April, 1901-1907 1,945,000 from 287,175 tons
July, 1908-April, 1918 923,455 from 269,056 tons
April, 1918-end of 1930— 5,200,000 from @ 607,000 tons
Total— $8,321,925
Dividends paid up to April 25, 1929, amounted to $3.21 a share or a total of $1,263,973. Total assessments levied up to 1929 amounted to $500,000.
Since 1930, the production has been coming from the Old Eureka section of the property.
Mine Workings
The Central Eureka shaft is 4965 ft. long on an average dip of 70°. It struck the hanging-wall or east vein at 500 ft. and followed it to about 2000 ft. in depth, where it passed into the slate in the foot- wall of that vein. It cut the intermediate vein below 2700 ft. and
76
AMADOR COUNTY
25 ft. below the 3425-ft. level entered the altered andesite, but below 4000 ft. again entered the slate. The footwall is black Mariposa slate nearly all the way. This shaft, like many other old ones on the Mother Lode which were sunk to follow the vein, has been expensive to keep open. The swelling footwall shoves shaft timbers out of line. Below
the 4500-ft. level, espe- cially difficult conditions were found, with frac- tured and moving ground. From the 4500- ft. level down, the shaft sets are of spruce logs 2 ft. in diameter with jacket S3ts behind them. These jacketed sets were tightly lagged to keep the ground from run- ning. The shaft has three compartments each 3 ft. 9 in. by 5 ft. in the clear. Two are skip- ways and one a man- way. Skips of 3 tons capacity operate on 52- Ib. rails laid 27 inches apart on the footwall plates of the shaft. The hoist in use was first installed at the Gwin Mine in Calaveras County in 1900 and was brought to the Central Eureka in 1920 and re- built. It is operated by a 300-h.p. motor.
Central Eureka shaft has been aban- doned below the 3350- ft. level. If experience with the nearby Old Eureka shaft is any guide it will be only a matter of time when the lower part of the aban- doned section and the lower levels collapse be- cause of hea^^ ground pressure, if this has not already occurred. Levels were turned at inter- vals of about 100 ft. to 200 ft. depending on conditions. The deepest level was at 4855 ft. (on 70° incline). From 1919 to 1930 the mine was deepened from 3500 ft. to the bottom with levels at 3500, 3600, 3760, 3900, 4100, 4250, 4400, 4550, 4700 and 4855 ft. During this
Headframe, Central Eureka Mine, showing skip runway In the form of a bridge truss.
Photo by C. A. Logan.
MOTHER LODE GOLD BELT 77
time the South Eureka ground was under option and was prospected on the 3350-, 3900- and 4100-ft. levels. The 3900-ft. level was run south 1180 ft. from the shaft, extending some distance into the South Eureka, and a crosscut was run 740 ft. east in the slate from this level through several vein formations and gouge seams, without finding ore. The 4100-ft. level was also extended into South Eureka ground. Due to shortening of the Central Eureka claim on the contact vein with increasing depth, an account of the converging end-lines, the purchase of the Old Eureka was important. The 4450-ft level was the most important in the mine, but on this level and on the 4400-ft. on the south end of the mine the ground became badly broken and had much gouge. Yery heavj^ timbering was required in drifts as well as in the shaft. Booms and lagging had to be used in places. On the 4855- ft. level a crosscut was run 240 ft. east and this struck a large body of 'gray ore' on which considerable prospecting was done, besides which the footwall drift was carried north 800 ft.
Geology and Ore Shoots
The Mother Lode belt at the Central Eureka is about 1600 ft. wide and composed mostly of Mariposa (Jurassic) black clay slate, in which occur in the westerly or footwall section, several beds of andesite or andesite porphyry. It is in that section that ore so far has been found. This series of rocks dips east at a steeper angle than elsewhere on the lode. The principal vein worked in the earlier operations was the so-called hanging- wall or east vein, which had an andesite bed for its immediate hanging wall. The ore shoot on this vein extended from near the 1000-ft. level to 2540-ft. level, was from one to 12 ft. thick and had its greatest stope length about the 1500-ft. level. The exact tonnage from this shoot is unknown but was probably about 300,000 tons which was worked with results noted (ante) between 1896 and 1907, averaging $7.16 a ton up to 1905.
Between the 2540-ft. and 3425-ft. levels, the mine showed most of those aspects which conservative engineers use as criteria of a worked out property. The most of rock milled did not pay expenses, and if ore were encountered it soon gave out. Contact, footwall and inter- mediate veins were all explored and mined with similar discouraging results. The average yield between 1908 and 1919 was only $3 to $4 a ton. The size of bodies of even this grade kept decreasing. The east vein was mined down to the 3350-ft. level with unsatisfactory results. The intermediate vein also fell off in grade and the stope length short- ened below 3000 ft. A crosscut was run 774 ft. east on the 700-ft. level without finding ore ; and on the 1800-ft. level, a footwall crosscut 717 ft. long gave no encouragement.
The first indication of better times was the occurrence of small lenses of good ore in the footwall gouge on the 3350-ft. level. Good ore two ft. wide was found on the 3425-ft. level. On the 3500-ft. level in 1919 a contact between slate and 'greenstone' (altered andesite) was struck 28 ft. southwest of the shaft. This contact was followed 215 ft. south by drifting and revealed from 2 ft. to 5 ft. of rock and ore assaying $2 to $7 a ton. A crosscut run 30 ft. west from, this drift revealed 3 ft. of fine ore. The main crosscut westward from the shaft was in crushed slate and quartz stringers. In this crosscut,
78 AMADOR COUNTY
33 ft. west of the greenstone contact, quartz was cut on the north side and on being followed it proved to be a good ore-shoot. From this north drift, a crosscut northeast to the 'greenstone' contact failed to show ore ; but 30 ft. farther north, another hanging-wall crosscut struck a small ore-shoot. In the floor of this north drift on the 3500-ft. level, a winze was started and at a depth of 85 ft. drifts were turned. The first 50 ft. on the north had an average width of 14 ft. and assayed $20 a ton ; for 80 ft. on the south it was even better. This ore was ribbon rock carrying a good deal of pyrophyllite. Thus what appeared to be two ore-shoots, separated by 160 ft. of low-grade vein filling, were found. In depth, however, the south shoot pitched north and they joined at the 3760-ft. level. On the 3760-ft. and 3900-ft. levels this footwall ore-shoot (which is difficult to correlate with previous ore bodies because of inaccessible workings, but is not believed by Albion S. Howe to be in the same vein mined above the 2540-ft. level) was 340 ft. long and averaged 9 ft. to 10 ft. wide, consisting of ribbon rock and gouge on both walls.
The most important and productive level in the mine was at 4550 ft. inclined depth on this ore-shoot. The shaft crosscut (running north- west) crosses a width of 60 ft. on that level that should probably be considered vein matter. North of this, the main vein (footwall vein so-called) was a stringer lead of crushed quartz and slate striking N. 40° W. and dipping 71° E., and the orebody had an average pitch of 45° NW. in the plane of the vein. On the east side, a spur vein striking N. 25° W. makes into the vein at this ore-shoot. This spur vein itself formed stoping ground for a length of 165 ft. from its junction with the main ore vein, which it entered about the center of the main ore shoot, here having a length of 425 ft. In cross section, west to east, the writer observed the following sequence in the stope above the drift : high-grade quartz ore in black graphitic schist, perhaps a phase of an altered dike; next, 8 ft. of quartz ore, on the hanging wall of which appeared the point of a 'greenstone' dike, 18 inches wide, separated from the ore by a small slaty gouge. This had on the east more of the graphitic schist. Here we have a fine example of the occurrence of an important orebody at a junction. Here the ore vein (footwall vein) and the contact vein meet or are linked by veins like this spur. Schistose altered greenstone appears close by in the footwall, and on the hanging wall are layers of slate interbedded with greenstone dikes or sills. A very rich streak of high-grade quartz, so finely crushed that it could be rubbed to powder in the fingers, traversed the spur vein diagonally to its junction with the main shoot. On the north and separated from the main ore body by 130 ft. of low grade, a quartz orebody 80 to 100 ft. long was found. This level yielded over 100,000 tons of ore, carrying $10 to $14 a ton. A width of 25 ft. was stoped in places.
The broken, heavy and moving ground encountered first in the south workings about 4400 ft. deep, passed downward through the 4700 ft. level station and the bins there were in it. It faulted the ore- body farther north with greater depth. The increasing cost of work when this cross fault entered the ore zone already crushed by subsidence or tension Assuring from the hanging wall, and the lower grade of ore, ended profits from this shoot on the 4855-ft. level. This vein gave out on this level 800 ft. north of the shaft, according to Albion S. Howe.
MOTHER LODE GOLD BELT
79
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80 AMADOR COUNTY
Crosscuts were run to the hanging wall 'greenstone' on the 4855-ft. level and one that penetrated it showed it to be crushed and badly shattered. Next to the slate hanging wall this greenstone is well min- eralized, and carries bunches and stringers of quartz. On the north end of this level, 600 ft. to 700 ft. north of the shaft the 'gray ore' formed in this greenstone is reported by James Spiers, superintendent, to be 60 ft. wide. While it was prospected only at intervals, there were indications of a large body of it which gave great variations in assay returns. This body appeared to have its apex along the 4700-ft. level and a little above it.
Milling, and Ore Characteristics
The 40-stamp mill has a capacity varying from 146 to 160 tons in 24 hours, depending on the condition of feed. The stamps weigh 1280 lbs. each fully shod, drop 96 times a minute and crush ore through 24-mesh screen. Concentrate is saved on Frue vanners. Kecovery has varied from 89.37% to 94.31% of mill-heads since 1920. The latter figure was obtained when mill heads averaged $13,148 a ton for a year, and was probably due to the greater proportion of coarse free gold, as compared to gold in sulphides. This proportion has varied considerably from year to year, having been nearly 6 to 1 from 1920 to 1925, 4 to 1 in 1926 and less than 3 to 1 in 1930. Crushed ore, unavoidably diluted by gouge and wall rock, lowered ore grades, and also recovery due to loss of fine sulphides. The percentage and value of concentrate ranged from 1.69% worth $107 a ton on the 3700-ft. level, to 2.8% worth $68 a ton at the 4700-ft. level. Tailing has varied in value from 64 cents to $1.12 a ton.
Information Circular 6512 of the U. S. Bureau of Mines, written in 1931 by James Spiers, superintendent of the mine, gives an excellent account of mining methods and costs at this mine.
Chicago, Conville, Giant and Reeves (Bartlett, Accident, A & B) claims are on the hanging wall side of the wide Mariposa slate belt a little southeast of Plymouth. There is little available concerning the results of work on them. The Chicago claim has a shaft reported to be 400 ft. or more in depth. Some of these claims have been pocket producers. The principal vein on the contact, with slate footwall and amphibolite hanging wall, does not appear to have been productive.
A & B claim had a shaft 175 ft. deep, two crosscut adits and an open cut 200 ft. long, run in search of pockets.
Creek Ledge prospect, a mile north of Plymouth on an agricultural patent, has a shaft 100 ft. deep sunk on the vein between the slate footwall and greenstone hanging wall. Vein varies from 4 ft. to 10 ft. wide. Only about 50 ft. of drifting was done on the 100 ft. level. No work has been done for over 20 years.
Detert Estate Group comprises 17 quartz claims in Sees. 11, 13, 14, 23 and 24, T. 7 N., R. 10 E., between Plymouth and Amador City, belonging in whole or in part to the estate of the late W. F. Detert. These claims, on which no work has been done in late years, were gradually accumulated over a long period by the late owner, who has left no record of the past operations, and apparently the only informa- tion concerning them is that appearing in past State Mining Bureau
MOTHER LODE GOLD BELT 81
reports and the notes gathered for the present paper. Names of the claims and acreages are :
Atlantic Q. M., 15.46 acres. California Q. M., 10.81 acres. Chili Jim Q. M., 4.56 acres (f interest). Cosmopolitan Q. M., 15.90 acres. Dry Creek Q. M., 5.5 acres. Eureka No. 2 Q. M. @ 10 acres. Gov- ernor Bradford Q. M., 12.091 acres (| interest). Henry Clay Q. M., 6.49 acres. Hercules Q. M., 15.59 acres. Joe Davis Q. M., 8.27 acres. New London Q. M., @ 18 acres (^ interest). North California (Web- ster) Q. M., 6.99 acres. North Eureka No. 2 Q. M., @ 5 acres. North Henry Clay Q. M., 11.89 acres. Pocahontas Q. M., 10.25 acres (f inter- est). Providence Q. M., 16.33 acres. South Cosmopolitan (Worley) Q. M., 14.29 acres.
The California, also called the Potosi, was the earliest of these mentioned. In 1867 it was said to have been worked since 1852 and had a vein 4 ft. wide. It was equipped with a 16-stamp mill. In 1876 it was idle, the shaft having reached a depth of 200 ft. It is reported locally that this claim produced $82,000 near the surface, but there is no definite record to substantiate this. In 1880, a new company repaired the mill, and the claim was said to have good ore. In 1884, nine miners took the mine "on a lay" under which they were to be paid wages if the company took the property back within a certain time. They made three 'crushings' of ore which averaged according to report $3.50 a ton. This came from an adit.
The California was also partly prospected from the Pocahontas shaft which was sunk vertically on the latter claim near the common side-line (See Pocahontas).
Cosmopoliian Group, before its purchase by Detert, included the Cosmopolitan, Dry Creek, South Cosmopolitan, Henry Clay, Provi- dence, and 142 acres of agricultural land. Between 1850 and 1890 considerable work was done on these claims. Cosmopolitan shaft was sunk 750 ft. on 67° incline with levels about 100 ft. apart from 200 ft. to 700 ft., inclusive. On the 200-ft. level, a drift was run north 185 ft. and on 400-ft. level, south 500 ft. On the 200-ft. level, a crosscut was run 107 ft. in the footwall and one 45 ft. west. Below this level, the greenstone of the hanging wall was reached only on the 400-ft. level. The vein is reported to have had an average width of 5 ft. with a slate footwall. The shaft was sunk in a faulted or crushed zone and struck the slate at about the 200-ft. level. Mo.st of the work is said to have been done in this disturbed area. There was a stamp mill on the claims in the 1890 's, but there is no record of production, though some mill tests were made.
Henry Clay claim has an old shaft 200 ft. deep, in which it is reported a vein 6 ft. wide was cut, with 4 ft. of gouge.
South Cosmopolitan claim has an adit 200 ft. long.
Pocahontas claim was prospected by a vertical shaft 620 ft. deep with levels at 74, 145. 310. 400 and 585 ft. in depth. This shaft was near the California claim's side line and the latter claim was partly prospected by the longer crosscuts, of which the following were run :
On 74-ft. level, west 178 ft.
On 145-ft. level, west 330 ft. to footwall vein, and east 120 ft.
6—4156
82 AMADOR COUNTY
On 310-ft. level, 561 ft. east cutting hanging-wall vein 150 ft. east of shaft.
On 400-ft. level, 200 ft. east.
On 585-ft. level, a drift was run south on the vein 230 ft. from a point 252 ft. west of the shaft.
In 1898, a lO-stamp mill was erected and the first bullion was shipped in February, 1899. There was also a small production in 1900, after which year there is no further record of activity.
So far as can be learned, most of the work done on these claims showed broken or disturbed conditions. Details of geological conditions underground are lacking, although current claims made during the progress of work indicated some good assays. In the work done through the Pocahontas shaft the country was explored from the massive diabase hanging wall to the Mariposa slate footwall.
El Dorado {May on) claim is on a narrow lens of slate lying in the hanging-wall greenstone immediately east of the Keystone claims, this slate being the north extension of the east belt of slate separated from the main slate by a large interlayered mass of greenstone, as mentioned under the Lincoln.
This claim was prospected by a shaft 300 ft. deep, on 45° incline with levels 100 ft. apart, and a length of 400 ft. was drifted. Vein is reported to have an average width of 5 ft. There is no record of production.
Fremont and Gover Mines cover 4200 feet along the strike of the Mother Lode, including Fremont, Gover, Loyal Lode Mine and mill site. North Gover, Bona Esperanza Quartz Mine and mill site, one-half interest in Bona Fortuna Quartz Mine and mill site and several parcels of non-mineral land.
History and Production
The Loyal Lode had a 20-stamp mill before 1867 and at an earlier date the quartz on the surface had been worked in arrastres; but by 1876 a depth of only 100 ft. had been reached and the claim was idle. Work was resumed in the 1880 's and in 1886 it was producing ore that yielded $7 to $8 a ton in free gold. In 1888, two ore-shoots were reported, one 200 ft. and one 80 ft. long between 'diorite' walls. Fourteen men were working and the 10-stamp mill was crushing 15 tons a day. The 200-ft. ore-shoot had been opened its full length and was reported 20 ft. wide. The work was done through 3 adits, the deepest 600 ft. long and 120 ft. deep at the face. There are no later records, and no details of the output.
The Fremont and Gover were consolidated at an early date and the company formed in 1872 worked principally in the Gover claim. The north or principal shaft finally reached an inclined depth of 1500 ft. (1050 ft. vertical). The only figures available indicate an annual output of from $50,000 to $70,000 in the late 1880 's and early 1890 's, with the last reported production in 1894. In 1888, ore yielded $9 to $13 a ton.
The Fremont shaft was started in 1900 and a new mill was built in 1903, containing forty 1000-lb. stamps and 16 Frue vanners. Fre- mont Consolidated Mining Company worked to a depth of 2950 ft. on
MOTHER LODE GOLD BELT S3
51° incline. They quit in December, 1918. Late in 1920, Metals Exploration Company began unwatering the property, and prospected it from 1921 to 1923. In the latter year, 20 stamps were put in oper- ation, but work was stopped in August. A new company, Fremont- Gover Mines Company, was incorporated at once by former employees, but they were unable to finance work long, and quit in 1925. Shortly after. Black Hills Fremont Mines Company did a little work in a shal- low adit and a winze 100 ft. deep on North Gover claim 600 ft. north of Gover shaft. This venture also was short-lived.
The only public record of the production of these mines previous to 1900 is for the period 1888-1894 during which Gover Improvement Company produced $259,389. Between 1900 and 1925, there was a reported output of about 930,000 tons which is said to have averaged about $4 a ton recovered ; in the later years of work by Fremont Consolidated Mines Company the mill-heads averaged between $5 and $6 a ton. There has never been much publicity about the earnings of the property, but in later years at least the margin of profit was small. Dividends are said to have amounted to $316,000. A total of $200,000 stock was issued.
Mine "Workings and Geology
The Fremont shaft was 2950 ft. long on an incline of 51°, with levels about 200 ft. apart. Drifting was extensive and aggregated several miles, the vein having been followed for 2500 ft. north from this shaft. The deeper of the Gover shafts, 1500 ft. long on the incline, is 1430 ft. north of Fremont shaft. Most of the work at this property had been done before the owning company quit in 1918. They had hoisting plants at both the above shafts, which were connected. The sinking of Fremont shaft to 2950 ft. was finished in 1918. The geology of the Gover mine and Loyal Lode was covered in Reports VIII, X, XI and XII of the State Mineralogist. As the Fremont is described in detail in U. S. Geological Survey P. P. 157 only a short summary is given here.
The Loyal Lode has already been mentioned. It is a claim over 2000 ft. long on the hanging wall of the main mine, and within the greenstone. In the Gover, two veins were developed which were sep- arated by a reef of black slate, sometimes only a gouge but elsewhere 90 ft. or more wide, and having greenstone as its hanging wall. The contact vein, next to the greenstone, produced the best ore, which often occurred in pockets as stringers extending into the greenstone, and contained arsenopyrite. The other vein was of slate-quartz ore. The contact ore shoot was over 300 ft. long. The slate-quartz shoot (having slate for both walls) was 280 ft. long. On the 500-, 600-, and 700-ft. levels, the veins were 15 ft. to 60 ft. wide. The contact vein pinched at 775 ft. and according to the Twelfth Report of the State Mineralogist it was not until the ninth level was reached that the shaft left the slate- greenstone contact, entering the greenstone. This point of departure (placed at a depth of 600 ft. by Knopf) marked the beginning of the principal 'gray ore' or schist orebodies, associated with the East vein after it passed into the greenstone. Here the low-grade orebody was reported to be 300 ft. long with an average width of 30 ft. The lode was explored for 1100 ft. south and 400 ft. north of the Gover
84 AMADOR COUNTY
shaft. At a distance of about 1000 ft. south of Gover shaft on the fourth level, the hanging-wall vein passed into the hanging-wall green- stone. A little south of this, the vein and wall rocks were faulted west.
The 1500-ft. level of the Gover, running south, connected with the 1350-ft. Fremont north drift, both being on the 'gray ore' zone, con- taining wide bodies of low-grade white quartz and lenses of 'gray ore,' which is hydrothermally altered greenstone containing from 3% to 5% of auriferous sulphide, mostly pyrite, which carried three-fourths to live-sixths of the gold. The largest 'gray ore' body extended do-wai to the 2300-ft. level, had a width up to 70 ft. and was in the angle between the slate-quartz vein and hanging- wall vein. Other lenses of 'gray ore' also were mined between the 800-ft. and 2500-ft. levels, among these being the 19 No. 2 South Shoot, 700 ft. south of shaft, and the 19 North Shoot under the shaft. These varied in width, their wider sections being 10 ft. to 25 ft. thick, with stope lengths up to 160 ft. The average value of m,ill-heads concealed wide variations. The upper levels of the Fremont shaft had developed the quartz-slate and pocket veins.
The mill operated by the Fremont Consolidated Mining Company handled about 200 tons daily and produced about 200 tons a month of concentrate which was worth $65 to $100 a ton. Concentrate was saved on Frue Vanners, and as mentioned before, carried from three-fourths to five-sixths of the gold. This mill saved 85% of assay value. Cali- fornia Slimes Concentrating Company worked the tailings on royalty, recovering about one-third of remaining gold by regrinding, concen- tration and cyanidation.
By way of contrast, it may be noted that in the early operations on the slate-quartz ore (Mother Lode vein) in the Gover, the concen- trate formed 2% of ore and was worth from $115 to $200 a ton.
Mining was partly done by square setting and partly with stulls, all stopes being filled. Toward the end of the owning company's operations, a total of 140 men were employed.
Good Hope Mine is on the west side of Jackson townsite, adjoining the Anita. It was held by one owner 34 years, during which time little was done. In 1896 a 10-stamp mill was built by Good Hope Mining Company and a shaft 130 feet deep on 80° incline was sunk by 1897, with a level at 70 feet from which drifts had been run 136 feet south and 40 feet north. The vein in the shaft is said to show 10 inches or more of auriferous quartz and four or five feet of slate with quartz stringers. In the drifts, the width of ore was reported to be seven feet or more, assaying well enough to pay, had it been in sufficient quantity. A second level was turned at a depth of 115 feet. The claim has been idle a long time, and there is no record of further work, if any was done.
Hardenherg Mine was worked through a shaft 500 ft. deep in early days, but details of the results are not available. It was reopened in 1890 and equipped with 10 stamps. In 1892, $23,500 was produced between the 300-ft. and 600-ft. levels, and in 1894, when work had reached the 800-ft. level $12,002 more was taken out. Work stopped in 1895 at a depth of 1000 ft. The last ore milled in 1895 averaged $4.19 a ton.
In April, 1911, the stockholders of the South Eureka Mining Com- pany began reopening and sank a vertical shaft 1100 ft. deep and in
MOTHER LODE GOLD BELT 85
1913 and 1914 reported production of 26,478 tons which yielded $65,970 or $2.49 a ton, principal!}^ from the 850-ft. and 1000-ft. levels. In both of the above operations the ground was found to be heavy, badly shattered and with a wide gouge on the black slate foot wall. At 800 ft. in the earlier workings the fissure was 15 ft. to 20 ft. wide and filled with slate, gouge and some quartz, and in the later work the heavy hanging wall and the gouge prevented mining clean ore.
In spite of these experiences a third reopening was begun late in 1916. About one year was spent in underground prospecting during which time the shaft was deepened to 1500 ft. and a level turned near the bottom. There is no record of production during that period. In March, 1918, the property was sold for the benefit of creditors and has been idle since. A 20-stamp mill put up for the use of the mine was found to be on ground outside the holdings.
Italian Claim is a patent of about two acres between the Seaton (Peerless) and Loyal Lead Claims. As originally located, it contained 302 ft. along the strike. The vein lies between slate footwall and green- stone hanging wall. In the early 1860 's it had a 6 stamp mill, and some 2000 tons of quartz from surface workings was crushed. About 1890 work was begun again and a crosscut was open giving a reported depth of 150 feet. From this a small quantity of rock had been crushed in the Seaton mill, with results now unknown. In 1932 the present owners started work through an adit level with its portal about 50 ft. south of the north line of the claim. This enters the footwall side of the wide vein. From it a crosscut was run 125 ft. to the greenstone of the hanging wall. Good assays have been obtained for a width of 10 to 15 ft. near the footwall ; also in a short drift started 45 ft. from the footwall in a southeasterly direction. Work was being continued late in 1933 with encouraging results.
Kennedy Mine holdings embrace, besides the original Kennedy claim located in 1856, the Bellwether, Clyde, North Clyde, North Clyde Placer, and Silva quartz claims and other land, 156 acres in all. The Zeila Mine, including the Coney and Bigelow, Blue Jacket claims and several agricultural tracts, 260 acres in all now belong to the same owners.
History and Production
Until 1871, the Kennedy was worked in only a small way, with a whim for hoisting. In 1871 the first hoist and a 20-stamp mill were erected. From then until November, 1873, the production was $183,427 from ore of an estimated average yield of $16.67 a ton. In 1873, two ore-shoots were being worked. On the north end, the Kennedy ore shoot was 150 ft. long and 2 to 12 ft. wide and had been worked to 400 ft. in depth. The Pioneer (Argonaut) ore-shoot was on the south end-line and at that time had been opened for a stope length of 170 ft. in the Kennedy. It was 18 ft. wide at the Pioneer line. Only four miners were employed in stoping to produce 20 tons of ore a day, the capacity of the mill. ]\Iining cost $4 a ton and milling $2.46 a ton. The mine produced $300,000 to a depth of 600 ft. up to the latter part of 1874. Soon after, the workings must have struck a lean zone as ore is said to have given out in the south shaft, with the raking of the
86
AMADOR COUNTY
ore shoot into the Pioneer claim. No ore was milled in 1875, when the deeper shaft was down 850 ft.
Evidently little was done thereafter until late in 1885, when the present owners, Kennedy Mining and Milling Company, took the mine. Unwatering began in January, 1886, and by October of that year a new 40-stamp mill with 16 Frue vanners had been erected, and 32 stamps were in operation. In an article published locally in July, 1886, it was stated there were large bodies of ore in the mine, "that could not be made pay under the expensive mlethod of working 15 years ago. ' ' It was also stated that an examination of the books "shows that the last 2000 tons of ore crushed yielded an average of over $6 a ton in
Headframe, Kennedy Mine.
Photo by Walter W. Bradley.
free gold. As the property was then fixed, running mill and mine by steam, and using 12 or 13 cords of wood per day, and crushing with 20 stamps of 400 lb. each not more than 20 tons per day, it cost about $16 per ton to mine and mill the rock, representing a loss of $10 on every ton crushed."
The new mill and hoist were designed to run by water power, and it was believed a profit could be made on the ore. The shaft was a little over 900 ft. deep, but the 900-ft. level had not yet been turned.
That the expectations of the company were realized, was shown by a statement published early in 1897, that in the past ten years the Kennedy had produced $3,580,000, of which $2,000,000 was claimed to have been paid in dividends. Approximately 36,000 tons of ore is
MOTHER LODE GOLD BELT 87
said to have been milled annually during this time (the mill having been erected under a guarantee to crush 100 tons a day). An interest- ing sidelight was throAvn on the grade of some of the ore mined during this period by evidence in two suits of Argonaut Mining Company versus Kennedy Mining and Milling Company, the first started August 11, 1894, and the second August 5, 1897, with a decision dated March 13, 1899. Testimony was given that 2604 tons of ore mined from ground south of the Kennedy south line on the 1450-, 1550-, 1650- and 1750-ft. levels had yielded ^$62,218.45 or $23.89 a ton. A cost of $6,119.40 or $2.35 a ton was allowed for mining and milling this.
The company has maintained a policy of secrecy and few authentic data have been published in 30 years about the results of mining. Storms in 1900 estimated the total cost (not including depreciation and depletion) to be $4.50 to $5 a ton. Work had then reached a vertical depth of 2300 ft. About that year the new vertical shaft was started 1950 ft. east of the north shaft. This eventually struck the two veins and has been the main working entry since 1904. In that year, a new 60-stamp mill was in full operation at this (east) shaft, as well as the old mill of 40 stamps at the north shaft. Ore was coming from levels between 1800 and 2550 ft. deep and 250 men were employed. From then on the mine was the deepest and largest producer on the Mother Lode for many years until the Argonaut began to vie with it. The' larger mill was increased to 100 stamps and for 12 years up to 1916, from 140,000 to about 170,000 tons of ore was crushed annually. This was taken mainly from the section between 2250 and 3450 ft. deep. The veins ranged from 5 to 30 ft. wide, the usual width being from 5 to 12 ft. Sometimes high-grade quartz was struck, but yearly average mill returns were reported to be $4 to $5 a ton.
With increasing depth (4050 ft. vertically in 1920 and over 5000 ft. by 1932) and increasing cost, it has in late years been necessary to mine more selectively, with a resultant decrease in tonnage milled, and an increase in gold content of ore to one-third or two-fifths of an ounce per ton. The workings have reached a depth of about a mile vertically. Since the last report (in 1927) the mine suffered a disastrous surface fire September 7, 1928, which destroyed all surface plant except the mill and main office, and resulted in damage underground. The plant was replaced and work in the mine resumed by the middle of 1929. In 1931 as a result of successful experiments, the flotation process was installed to handle plate tailing. Since 1929 work has been done in the lowest levels through a 65° 3-compartment inclined winze sunk from the 4650-ft. level with the last level at 5250 ft. This last level has not so far proved as productive as might be wished, and output has been curtailed lately.
Figures given in a report by Waldemar Lindgren (Mineral Deposits, 1919) for the production of the Kennedy Mine to the close of 1915, and quoted by the present writer in a previous report appear to be erroneous. The mine had produced over $14,500,000 up to that time, and its total output to the close of 1933 has been approximately $25,000,000. As the stock has been closely held, the amounts of divi- dends and assessments have never been published. Dividends of about $5,000,000 have been reported from reliable sources. Between 1918 and 1924 due to the expense and loss of time incident to unwatering
88 AMADOR COUNTY
the mine after the Argonaut fire, the operations are alleged to have resulted in heavy assessments. Thereafter, some profit was possible for several years. The company was started with a capitalization of only $100,000 which was never increased.
Recently, a cyanide plant has been built to treat the large accumu- lation of tailings.
Geology and Mine Workings
The Twelfth Report of the State Mineralogist (1894), gives a good account of the geologic conditions found to an inclined depth of 2000 ft. A cross-section at the south shaft, beginning with the footwall green- stone and going east, shows : Vein 4 ft. wide, black slate 80 ft. ; green- stone 200 ft. ; black slate 250 ft. ; greenstone 30 ft. ; black slate 35 ft. ; greenstone 300 ft. and so on, slate and interlayered bands of greenstone alternating. The slate and greenstone were contemporaneous in the narrow bands and the gradation from one to the other so gradual as to make a classification arbitrary. The quartz of the vein continued in the west greenstone-slate contact to a depth of about 300 ft. near the north shaft and 750 ft. at south shaft. Below this, in crossing the slate, the fissure is said to have shown only crushed and foliated black .slate, with quartz in small seams and broken fragments. It struck the contact of the next easterly band of greenstone and began to make quartz again at 950 ft. near the south shaft and at the 1450-ft. level opposite the north shaft, forming from these depths another ore zone to about 2000 ft. in depth where another strip of slate was encountered, with poor returns in it.
The Kennedy vein continued in this manner, crossing the various layers, as its eastward dip is at a smaller angle than that of the rock layers through which it passes. Due to the breaking away of an immense 'horse' or lens of country rock from the hanging wall an east vein was formed, starting between 1700 and 2200 ft. in depth and separated from the west or footwall vein by a maximum thickness of about 150 ft. of the 'horse.' Both north of the deep vertical shaft on the 3900-ft. level and south of it on the 4300-ft. level, these veins began to merge, and in the adjoining Argonaut workings on the south there is only one main or footwall vein through this entire depth. Another important factor was the irregular downward course of the Pioneer (Argonaut) north orebody which occurred near the end-line separating the two mines. In places it was partly in each mine ; elsewhere, it raked north or south far enough to carry it entirely into one property, as between the 3600-ft. and 4200-ft. levels of the Argonaut, where its north pitch carried it into the Kennedy ; below there it returned to the Argonaut, furnishing a large tonnage of ore in the deeper levels of that mine.
The veins swelled abruptly into lenses which furnished ore. Both branches furnished orebodies near and at their north junction to form the main vein but the footwall vein was more important. In later years a length of from 1400 to 1600 ft. along the strike was explored on some levels. In the middle levels, now closed, the ore was reported in lenses over a length of 800 ft. ; with from 7 to 11 ft. of ore on one vein and 6 ft. on the other, the lenses of ore lying en echelon. On the 3900-ft. level, where the two veins joined 140 ft. north of the shaft, a
MOTHER LODE GOLD BELT
89
large orebody was formed and was followed northward several hundred feet. On the 4350-ft level south of the shaft they were separated by 33 ft. of filling, and on the 4500-ft. level they were separated by only a few feet of slate. Here the footwall ore body lengthened to 700 ft. and gave fine assays. The grade of ore had begun to improve in 1924 and probably more selective mining from then on had improved mill heads. Ore from the 4350-ft. level in 1926 averaged $10 a ton and since that time the average grade of mill heads has continued higher than previousl5^
The average thickness of ore mined has ranged from 8 to 15 ft. In places 30 to 40 ft. in thickness was worked and Knopf mentions a
Kraut 6-cell flotation unit in mill of Kennedy Mine, Jackson, Amador County.
Photo by Walter W. Bradley.
maximum stope width of 112 ft. The lenses of ore pinch and swell abruptly both on the strike and dip. The superintendent distinguished the ore from the hanging-wall vein as more slaty and with more sulphide than that in the footwall vein which showed more free gold and pyrophyllite (hydrous silicate of aluminum) possibly the same mineral called by Knopf damourite (hydrous silicate of aluminum and potassium). Generally the best ore was the banded or ribbon rock, of hard white quartz with numerous ribbons of finely ground slate and often ribbons of fine-grained pyrite and galena, showing building up of the vein by repeated opening. Wliere coarse free gold occurred it was generally associated with the light green pyrophyllite ( ? ) .
1)0 AMADOR COUNTY
Carlton D. Hulin in 1930^ published the results of a study of some specimens of high-grade ore mined in 1925 from the 3900-ft. level. He found the principal gangue mineral in these was fluor-apatite. The minerals which he classified in the specimens and the order in which he decided they had been deposited were : quartz, apatite, strengite, pyrite, sphalerite, sericite, carbonates, galena, chalcopyrite and gold. He concluded the apatite was here the common host for gold because apatite has well-developed cleavages and tends to fracture easily, and quartz was the least favorable of these minerals for gold deposition because it lacks cleavage and is tougher than the others. Galena and chalcopyrite were favorable, and often showed gold.
The recovery of concentrate in late years (up to the time the flotation plant was installed) was less than 1% of ore milled. The flotation tests (described under Metallurgy herein) emphasized that the ores from different parts of the m;ine varied and that the apparently low sulphide content was due at least in part to ore not being crushed fine enough to release all gold and sulphide. The concentrate has been high grade for a Mother Lode mine, carrying six to seven ounces of gold a ton, which might indicate loss due partly to table adjustment in the effort to make a very clean product.
In late years milling was done with 100 stamps and later with 60, followed by 40 Frue vanners for rough concentrate and two Frues for cleaning concentrate, with tailing from these last two vanners returned to the stamps. Up to about 1915 or later a canvas plant was used to treat tailing, with Gates concentrators and bumping tables ; a chlorina- tion plant was also in use many years. The stamps crushed 4^ to 5 tons each daily through 24-mesh screen and though definite figures are not available, recovery was probably 83% to 90%. Tucker gave the lower figure in 1914
The vertical shaft, started about 1900 at a distance of 1950 ft. east of the vein and old north shaft, has been the main working entry. It has three compartments each 4 ft. by 5 ft. in the clear. It cut the east vein at a depth of 3680 ft. ; and west vein at about 4000 ft. It is 4764 ft. deep, being the deepest vertical shaft in the State, and has vindicated the judgment of the operators, giving very little trouble. Hoisting in this shaft was done by steam, using oil for fuel from 1906 to 1926. A total of 1800 h.p. was available but normally 1200 h.p. was used, with a maximum hoisting speed of 2200 ft. per minute with 4-ton skips. In 1927, electricity was substituted for steam, using 800 h.p. and reducing the hosting speed to 1500 ft. per minute. A new surface plant except mill and office had to be installed after the 1928 fire, including a new steel head-frame. Three compressors at this shaft are each operated by a 225-li.p. motor.
The recent work underground has been through a 3-compartment inclined winze sunk on an angle of 65° from the 4650-ft. level 200 ft. from the vein. The deepest level late in 1933 was at 5250 ft. Mining has been done with square-set timbering, filling with waste from cross- cuts and chambers.
About 80,000 gallons of water daily has been hoisted with 1100- gallon water skips from the sump and from tanks on the 500-, 1000-
lEconomic Geology. Vol. XXV, No. 4, June, 1930.
MOTHER LODE GOLD BELT 91
and 1900-ft. levels. Though generally dry in the lower levels, a pocket of water may occasionally be struck in watercourses on either wall.
Tailing has been stored for 20 years behind a concrete multiple- arch dam 455 ft. long by 43.8 ft high as originally built, but planned to be raised to 50 ft. To reach this about 2000 ft. of flume was built and 4 tailing-elevator wheels were used. These are 68 ft. in diameter, with 176 buckets each and each was run by a 15 h.p. motor. In 1933, a new earth-fill dam was built.
Keystone Mines Corporation now owns the Keystone, Spring Hill, Geneva, Niagara and East Keystone comt)rising the Keystone group ; and Medean, Talisman and South Spring Hill, formerly called South Spring Hill Mine. These claims cover over a mile in length on the Mother Lode at and near Amador City, and contain 280 acres.
History and Production
Spring Kill Mine was the second group of quartz locations made on the Mother Lode in the county, and was locally called the Ministers' Mine, from its locators, who were preachers. It failed to realize the extravagant hopes of its finders. They lost it in 1854, and the new owners in 1855 produced 2221 tons of ore which yielded $21 a ton at an operating cost of $10.50 a ton. Although the shaft was 350 ft. deep and 50,000 tons of ore had been crushed in the 30-stamp mill by 1867, it was said it had paid little, if anything, above expenses. The Talis- man (Herlertville) claim likewise, with a 600-ft. shaft and a 30-stamp mill before 1860, had not done so well. It remained a separate mine until the late 1890 's and between 1890 and 1892 produced $48,316. The Medean claim also was listed as a separate producer in 1894 and 1895, with an output of $26,600.
South Spring Hill Mine, like all those in the holdings, was located in 1851, but apparently did not become an important producer until the late 1880 's. In 1887 it had been opened to a depth of 800 ft. and the 30-stamp mill was crushing 70 tons of ore daily. From 1888 to 1902, inclusive, a production of $1,092,472 was reported. There are no figures of tonnage available, but the ore was stated in 1887 to vary in gold content from $3 to $40 a ton and in width from 1 ft. to 50 ft. This is one of the mines about which very little has ever been pub- lished, and over 30 years have elapsed since the last work was done. In 1897, previous to which year most of the production was made, it was locally reported that about $250,000 had been paid in dividends. The South Spring Hill shaft was sunk 1200 ft. on 60° incline with 11 levels 100 ft. apart, and over 14,000 ft. of drifts were run.
Talisman and South Spring Hill shafts are about 2300 ft. apart and connected underground. Both have the Mariposa slates on the w^est and greenstone on the east. The principal ore shoot is reported to have had a stope length of 500 ft. and an average width of 5 ft. The South Spring Hill group became important to its neighbor, the Keystone, when it was found tlie Keystone orebodies were trending in depth toward the South Spring Hill. This was given as one of the reasons for closing the Keystone in 1920. Thereafter, the group was sold to the Keystone.
92 AMADOR COUNTY
Keystone Mine grew up about the mining locations of the Granite State and Pleasant Ridge Companies, themselves formed from several claims located in 1851. The Granite State claims were the third group of locations made on that section of the lode, and there were six original locators forming the company, each claim being 60 ft. wide by 120 ft. long. One claim showed particularly rich outcrops, and four arrastres were built to crush selected ore which paid $100 a ton for a few months. A one-half interest was then given in the claims for a 12-stamp mill, but within two years the project failed, and the claims were purchased at sheriff's sale by A. H. Rose of the Pleasant Ridge Company and the Keystone Mine thus came into existence in 1853.
In 1854 a total crew of 18 men produced 2204 tons of ore which yielded $21 a ton, or a gross of $46,284. The total operating cost was nearly $15 a ton, and monthly dividends of $200 a share were declared. By 1867, a total of 44,000 tons had been worked, giving an average yield of $16 a ton or $700,000 in all. The mine had been sold to Gash- wiler and McDonald for $102,000 and like so many other of the California gold mines remained practically a one-man or family affair for many years, with only a partial record of results of operation pub- lished. Some of these were :
From December 8, 1865, to December 21, 1866, production $135,- 333.30, dividends $51,300. Average recovery, $16 a ton.
For the year ended July 31, 1868, production $154,354.87 from about 12,000 tons of ore, average yield $12.86 a ton ; dividends $75,000.
For the fiscal year of 1870, estimated $25,000 gross and $15,000 net production monthly.
For the fiscal year of 1871, estimated gross output $300,000 ; divi- dends during calendar year of 1871, $20,000.
For 1872, from $35,000 to $40,000 gross a month during the greater part of the year was estimated, but the record of dividends on the San Francisco Exchange showed only one of $5,000.
For 1873, dividends of $185,000.
In 1874, 25,146 tons of ore yielded $452,507 or $18 a ton at a cost of $7.16 a ton for mining and milling.
In 1875 it was said that since 1870 the production of the Keystone had averaged $1,000 for each working day. As the mill then in use contained forty 750-lb. stamps and had a capacity of 90 tons a day, this average, if correct, would indicate a yield of over $11 a ton for the period. The mine had then been opened to a depth of 750 ft. and for a length of 900 ft. The details of output from 1875 to 1888 are not at hand. However, the good grade of ore for which the mine had been noted gave out about 900 ft. in depth when the vein entered the green- stone. From 1888 to 1919, inclusive, the production was about $4,400,- 000. Keystone IMining Company were the last operators and ran the property from 1911 until October, 1919. They worked ore which yielded as little as $2.40 a ton.
Mine "Workings and Geology
The first official mention of the geology of the Keystone was by Dr. J. B. Trask, first State Geologist of California, in 1854. He reported the vein 3 ft. wide at a depth of 9 fathoms from the surface
MOTHER LODE GOLD BELT 93
in an adit 100 ft. long. At the end of this adit a shaft had been sunk through the lode 7 fathoms. There was a level 94 ft. long at the bottom of the shaft "with a power in the lode of five feet." The same writer in 1855 stated that "The lode at the depth of twenty-one fathoms has a power of nine feet for one hundred feet in length" and also that "At the depth of seventeen fathoms the ores lose the character of porosity which in the superficial ores was a striking characteristic, the cavities containing free gold. ' ' The Keystone vein in the upper levels had an average width of 10 ft. and the Geneva vein, 280 ft. east of the Keystone, was from 3 to 7 ft. wide. In 1867 a depth of 375 ft. had been reached and a length of 450 ft. on the strike had been drifted, all in ore. Professor Ashburner, in an early report on the Keystone vein, stated "The ground in many places is loose and the vein seems to have been subjected to great pressure, crushing the quartz to powder." The contact vein, with black slate footwall and altered greenstone hanging wall was a massive vein 12 to 200 ft. wide, but generally low grade. The pay occurred where side stringers made into the main vein from the footwall slate. These dipped 47° east. This massive barren vein occurs on the hanging-wall side of an important fault that has been traced 2000 ft. and dips east 35° to 65°. The vein is composed of frag- ments of greenstone and slate. The appearance of the mine in 1875 when it was known as the leading mine of the Mother Lode, is graph- ically described by Raymond :
•'* * * The ore bodies in the slate which form the principal source of the company's revenue are of variable extent, sometimes expanding- to a width of 20 ft. and again contracting to a mere seam. It has been noticed that the expansion generally occurs when the vein flattens, and contracts where it approaches a vertical dip. In consequence of this marked peculiarity in the west veins, the ground is prospected by vertical winzes which answer the purposes of horizontal crosscuts in more regular veins. By this means the mine always presents large bodies of reserves which would almost invariably have remained undiscovered by the usual system of prospecting. The Keystone has been explored to a depth of 750 ft. and a length of 900 ft. The longest crosscut is about 300 ft. On the east is found a well-defined wall of greenstone, carrying with it a vein of low-grade quartz. There is properly no footwall but a well marked line of fracture is found presenting the peculiar feature known as slickensides about 300 ft. west of the greenstone. Beyond this, exploration has failed to disclose bodies of quartz although a crosscut has been run 120 ft. beyond the line of fracture. The yield of quartz in this miine varies from 110 to $20 a ton."
On the hanging-wall side of the low-grade vein and separated from it by a dike of diabase, a small vein was found in a strip of black slate. This carried arsenopyrite and pockets of gold, the largest of which was found between the 800- and 900-ft. levels and was reported to contain over $100,000. The banded slate ore of the west vein was finally stoped for a maximum length of 800 ft. and an average width of 15 ft. down to the 900-ft. level.
Below 900 ft. in depth the main fissure passed into the greenstone, dipping flatter than the contact and traversing the greenstone to a point estimated to be somewhat below the 2100-ft. level, where, if it main- tains its observed dip, it is presumed it will enter the east slate. This vein varied greatly in width however, being in one place 54 ft. wide, and only a seam on the 1400-ft. level ; so its possibilities and its positive identification below may be uncertain. All workings have been inac- cessible since 1920, and notes below are from the management.
The main or Patton shaft was sunk 2680 ft. on 52° incline, being in greenstone from 1400 ft. to the bottom. On the 1200-ft. level, 800 ft. north of the main crosscut, an ore shoot parallel to main vein was found
94 AMADOR COUNTY
which was reported 130 ft. long by 8 ft. wide, of 'gray ore' assaying $8 or more a ton. On 1400-ft. level, 150 ft. north of main crosscut, the vein branched. A drift was run 650 ft. on the west branch, which was reported to show ore 8 ft. wide at this place. A drift 270 ft. long on the east branch was in low-grade material. The gray orebody pitches south, being 400 ft. or more north of Patton shaft on the 1400-ft. level and 600 ft. south of it on the 2100-ft. level, where the orebody was 100 ft. long and was mined for a width of 18 ft. This 'gray ore' is mineralized greenstone on the hanging- wall side of the main contact vein. Ore was formed by the hydrothermal alteration (ankeritization) of the greenstone, during which gold-bearing sulphides, principally pyrite, were deposited forming a disseminated orebody in which most of the gold is associated with the sulphide.
On the 2100-ft. level, 1700 ft. of crosscuts were run and on the 2650-ft. level crosscuts were driven to both contacts of the greenstone and several hundred feet of drifts were run, but no ore was developed on this level within the Keystone ground. A block of ore remains above the 2100-ft. level on the gray orebody. The owners estimated in 1927 that there was 200,000 tons of proved ore that would yield $3 a ton at the old price of gold. The vein flattened on entering the greenstone to a dip as small as 20°, and this carried it far east of the original contact it had occupied. The crosscut west on the 2650-ft. level was run 690 ft. through greenstone and drifts were run 350 ft. north and 450 ft. south without developing ore. It was supposed that this work was on the downward extension of the so-called west vein so profitable above 900 ft. but this was of course not absolutely certain. Only a gouge-filled fissure was found in the slate. The crosscut was then run 500 ft. farther west, crossing a body of slate 380 ft. wide. In the south drift, 400 ft. south of the crosscut, another crosscut was run 275 ft. in the slate without finding ore. There was also a crosscut on the 900-ft. level 150 ft. east to Spring Hill vein, with a drift north on the vein 800 ft. and south 300 ft. At the 1200-ft. level a crosscut was run 320 ft. to the east vein and considerable work was done upon it, connecting with the old workings. There is an old south shaft 1124 ft. long on an incline of from 42° to 55° which was used for pumping.
The ore, as already noted, varied a great deal in value; the best of it in the deeper section of the west vein workings in the slate in the 1880 's was several hundred feet west of the greenstone, was from 3 ft. to 40 ft. wide and yielded as high as $40 a ton. It carried from 11% to 1|% of sulphides, principally pyrite with some arsenical and antimonial sulphides, which yielded $110 a ton. On the basis of ore averaging $11 a ton this would mean about 15% of the gold in the sulphides. In 1906 at a depth of 1000 ft. with ore that yielded $2.43 a ton there was 2% of concentrate worth $63 a ton and carrying 52% of the gold and silver. In 1917 with ore of nearly identical yield, sulphides formed 4.3% of ore, yielded $53 a ton and contained 95% of the gold and silver. This last was the "gray ore" or ankeritized greenstone.
The last mill (still on the property) contained 40 stamps which, in the later operations, gave a reported capacity of 6 tons a day per stamp for an entire year. There seems to be a reasonable doubt that the mil] gave an average capacity of over 4 tons per stamp per day. This
ACCOMPANYING BULLETIN 108. BY C.A.LOGAN
MOTHER LODE GOLD BELT 95
would give an average recovery of about $3.80 per ton crushed from 1914 to 1919 inclusive. Vanners were used for concentration and no tailing was saved, as their gold content was verv small. Recovery was about 90%.
During the last three vears of operation most of the ore came from the 900-, 1000-, 1200-, 1400-, and 1800-ft. levels, the last three being most important, with little from the 2100-ft. level.
Krueger and Vaughn claims are near the Amador Queen No. 1 on the south. These claims were worked in 1852 using arrastres, and in 1855 some ore was milled, yielding about $7 a ton. Little appears to have been done after the work necessar}- for a patent was complete. These claims are on the east side of the main slate belt two miles south of Jackson.
Lincoln Consolidated Mines include the Lincoln, Belmont or Iowa, Stewart, "Wildman, Mahoney, South Malioney and South Lincoln pat- ented claims, 11 small unpatented claims, mineral rights under town lots in Sutter Creek and other adjacent lands, 380 acres in all and covering about 5900 ft. in length along the Mother Lode. The hold- ings formerly were three separate mines, the Lincoln, Wildman and Mahoney.
History and Production
The Lincoln was located about 1851, and the others about the same time. All three were worked during the 1860 's. The Wildman had a shaft 530 ft. deep and a 12-stanip mill in 1867. It lay idle from then until 1887, when it was reopened by Wildman Gold Mining Company. The Lincoln had two shafts by 1867, one 669 ft. deep and another 270 ft., and was said to have produced 3500 tons of ore annually from 1851^ to 1867, except for two years. There was a 20-stamp mill and some of the ore was worth $15 a ton. The Mahoney had been opened to a depth of 500 ft. by 1873. The vein was 45 ft. wide then. It had been profitable to a depth of 250 ft., but below there was in low-grade material. The early-day production from the Wildman to a depth of 500 ft., the Mahoney to a depth of 300 ft., and from the Hector portion of the Stewart is estimated to have been about $1,500,000. The Mahonev was 900 ft. deep when bought bv the Wildman Company in 1894.
The Wildman and Mahoney were worked by the Wildman Gold Mining Company until 1906, then closed down until 1910, when they were reopened and prospected until 1912, since which year they have been idle. The Wildman shaft reached a depth of 1400 ft. on 72° incline; Mahoney shaft, 1200 ft. deep on 62° incline, and Emerson vertical shaft 616 ft. The Lincoln, after lying idle about 30 years, was reopened in 1898 by Lincoln Gold Mine Development Company. The three groups were taken over by the Lincoln Consolidated Mining Company after 1906. The Lincoln shaft reached a depth of 2000 ft. on an incline of 63°. The Lincoln was not productive below the 500 ft. level, but the Wildman was stoped to about 1400 ft. and the Mahoney to 1200 ft. deep.
1 Browne, J. Ross, Mineral Resources of U. S., West of Rocky Mountains, 18C8.
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MOTHER LODE GOLD BELT 95
would give an average recovery of about $3.80 per ton crushed from 1914 to 1919 inclusive. Vanners were used for concentration and no tailing was saved, as their gold content was very small. Recovery was about 90%.
During the last three vears of operation most of the ore came from the 900-, 1000-, 1200-, 1400-, and 1800-ft. levels, the last three being most important, with little from the 2100-ft. level.
Krueger and Vaughn claims are near the Amador Queen No. 1 on the south. These claims were worked in 1852 using arrastres, and in 1855 some ore was milled, yielding about $7 a ton. Little appears to have been done after the work necessary for a patent was complete. These claims are on the east side of the main slate belt two miles south of Jackson.
Lincoln Consolidated 3Iines include the Lincoln, Belmont or Iowa, Stewart, Wildman, Mahoney, South Mahoney and South Lincoln pat- ented claims, 11 small unpatented claims, mineral rights under town lots in Sutter Creek and other adjacent lands, 380 acres in all and covering about 5900 ft. in length along the Mother Lode. The hold- ings formerly were three separate mines, the Lincoln, Wildman and ]\Iahoney.
History and Production
The Lincoln was located about 1851, and the others about the same time. All three were worked during the 1860 's. The Wildman had a shaft 530 ft. deep and a 12-stamp mill in 1867. It lay idle from then until 1887, when it was reopened by Wildman Gold Mining Company. The Lincoln had two shafts by 1867, one 669 ft. deep and another 270 ft., and was said to have produced 3500 tons of ore annually from 1851^ to 1867, except for two years. There was a 20-stamp mill and some of the ore was worth $15 a ton. The Mahoney had been opened to a depth of 500 ft. by 1873. The vein was 45 ft. wide then. It had been profitable to a depth of 250 ft., but below there was in low-grade material. The early-day production from the Wildman to a depth of 500 ft., the Mahoney to a depth of 300 ft., and from the Hector portion of the Stewart is estimated to have been about $1,500,000. The Mahonev was 900 ft. deep when bought by the Wildman Company in 1894.
The Wildman and Mahoney were worked by the Wildman Gold Mining Company until 1906, then closed down until 1910, when they were reopened and prospected until 1912, since which year they have been idle. The Wildman shaft reached a depth of 1400 ft. on 72° incline; Mahoney shaft, 1200 ft. deep on 62° incline, and Emerson vertical shaft 616 ft. The Lincoln, after lying idle about 30 years, was reopened in 1898 by Lincoln Gold Mine Development Company. The three groups were taken over by the Lincoln Consolidated Mining Company after 1906. The Lincoln shaft reached a depth of 2000 ft. on an incline of 63°. The Lincoln was not productive below the 500 ft. level, but the Wildman was stoped to about 1400 ft. and the Mahoney to 1200 ft. deep.
1 Browne, J. Ross, Mineral Resources of U. S., W^est of Rocky Mountains, 18C8.
96 AMADOR COUNTY
There were three periods of production for these mines, of which the first was the production from the shallow zone to a depth of 500 ft. in the Lincoln, 500 ft. in the "VVildman, and about 250 ft. in the Mahoney. The exact figure for the total output for this period is unknown, but has been estimated at $2,000,000 for the Lincoln (prob- ably excessive), and $1,500,000 for the Wildman and Mahoney, prior to 1887.
In 1898 and 1900 in the course of cleaning out the old workings and prospecting, $22,000 was produced from the second, third and fifth levels of the Lincoln.
The Wildman Gold Mining Company started with a 10-stamp mill, which was enlarged to 20' stamps, then to 30. From 1887 to May 1, 1894, they produced from the AVildman Mine 94,206 tons of ore which yielded a gross output of $417,561, after deducting freight and smelting charges on concentrate, and bullion refining charges.
From 1894 to October 1, 1901, they produced from the Wildman property 234,945 tons of ore of a total gross value of $834,671, or $765,347 after deducting for freight, smelting, etc. In the same period they produced from the Mahoney 269,681 tons which yielded a gross output of $518,037, or $439,471 after deduction of freight and treat- ment. Between 1895 and 1899, inclusive, the total average cost of min- ing- and milling, including development and other improvements except enlarging mill, was $2.59 a ton. During this time, the operations at the Wildman yielded a net profit of $211,712. The operating loss at the Mahoney was $144,040. Each mine was equipped with a 40-stamp mill, containing 750-lb. and 950-lb. stamps. There is no record of any production between 1910 and 1912.
Geology and Mine Workings
The Mariposa slate between the Old Eureka Mine and Amador City is interbedded with several narrow bodies of greenstone and the mines of the company are grouped around the slate-greenstone con- tacts. The andesite has been in part altered to amphibolite schist. Going north from the Wildman the vein increased to 45 ft. in width on the surface, and is said to have supplied much rich ore in the early days. It branched, or was split by a greenstone horse, at the north end of the Mahoney, one branch turning eastward into the Hector portion of the Stewart, with greenstone on the footwall, the other branch passing into the Lincoln with schist, and farther off, greenstone on the hanging wall. There was usually a heavy gouge, with ore at times on both sides of it. The ore in the Wildman and Mahoney was in the contact vein, along the schist-slate contact, in the upper levels. At depths reached in the earlier operations, namely about 500 ft. deep in the Wildman and 250 ft. in the Mahone}^ the mineralization began to pass from the contact into the schist, where large bodies of low- grade altered schist, impregnated with pyrite, were found. The gray schist ore was on the footwall of the solid quartz vein. The wide section of rock on which mineralizing solution acted resulted in dis- persal of the gold to such an extent that it was necessarily lower grade than if it had been confined to a narrow fissure. The schist dike was from 60 to 295 ft. thick. Mining in the contact vein continued to the 1300-f t. level, in the period between 1895 and 1899, the ore coming from
MOTHER LODE GOLD BELT 97
that vein between the 500- and 1300-ft. levels and being of low average grade. In 1899 the development of small ore-shoots found by diamond drilling in the schist dike began. As they had no dump room for waste on the surface, they milled everything that would pay for crushing, and the average grade was far below that needed to make ore, even at the low cost of operation.
After the Lincoln shaft was sunk to 2000 ft. a drift was run south over 2200 ft. passing through the Mahoney claim and to a point under the Wildman 1400-ft. shaft. Long crosscuts were run into the footwall from the 500-, 1200- and 1950-ft. levels of the Lincoln shaft, and on the 1200-ft. level one Avas run into the hanging wall, all apparently without finding ore.
In the Wildman Mine, the north drift on the 1400-ft. level was run 437 ft. and the south drift 666 ft. For a length of 250 ft. on the north, the vein averages 5 ft. wide, but the assay value is not known. In the south drift, according to information furnished from owners' records, ore began to make 193 ft. south of the shaft and increased to 25 ft. in width within 185 ft. A horse of ground had slipped into the fissure here, causing a pinch in the vein for about 75 ft. Beyond this, the vein began to widen again, increasing from 10 ft. just south of the horse to 100 ft. wide at the face. This latter width was sampled in sections of 5 ft. each, and the resulting average of the 20 samples was reported to be $3.62 a ton. The general pitch of the Lincoln-Mahoney- Wildman orebodies appears to be southward, as is true also in the mines nearby on the south.
Little Illinois Mine is on the J. H. Thomas Ranch containing 537 acres, lying to the south of the Pocahontas mine. Some work is reported to have been done here in the 1860 's, but no record remains of it. It was reopened between 1908 and 1914, and a few tons of very good ore was reported crushed. The shaft was 147 ft. deep late in 1914 when last visited, and only 150 ft. of drifting had been done, 100 ft. of it in a shallow tunnel. It was closed down soon after, and has been idle since.
The workings are reported to have shown a vein with an average width of 5 ft., between slate footwall and greenstone hanging wall. Nothing is known regarding the prospects, as the last operator, Little Illinois Mining Company, left no records.
Mammoth Mine is on the 'black metal belt' in Spanish Gulch, adjoining the Valparaiso on the south. Its earliest history is unknown, but in the early 1880 's it produced some rich ore. Between 1885 and 1888, a tunnel 8 bj^ 8 ft. in cross section was run 3500 ft. northerly. For 3300 ft. no ore worth speaking of was found, except some small seams. AVhen a point was reached about under the earlier strike, and 800 ft. below the surface, quartz increasing from small stringers to nearly the width of the tunnel was entered, and this carried some of the typical rich ore of the belt, containing arsenopyrite and gold. In 1886 there was a 10-stamp mill on the mine, but the rich ore was mortared by hand.
Little appears to have been done at this property in late years, the only recent record of production being of a few thousand dollars in
7—4156
98 AMADOR COUNTY
1924. Knopfs states the ore occurs "in horizontal veinlets of quartz that are restricted to the vicinity of the contact of black slate and green- stone. The veinlets follow horizontal joint surfaces, and most of them are but a few inches thick."
Moore Mine. This old mine (on agricultural land a mile and a half south of Jackson) had been idle over 30 years when Moore Mining Company began reopening it under option to purchase in August, 1921. There is no record of the results of the operations in the 1880 's, during which the mine had been opened to 640 feet, on an incline of 52°.
When the shaft was reopened it was found that the fifth level (435 ft. inclined depth) which had been drifted 400 ft. in the heavy, crushed black slate in the main fault, was caved full. It was reopened, but did not carry pay. The black slate there is about 60 ft. wide. In a fissure branching from the main fissure, and striking nearly due east into the greenstone on the hanging-wall side a vein of quartz ribbon rock was found which carried from 4 to 12 ft. of ore. This gave such flattering prospects that a new 20-stamp mill and other buildings were erected in 1922 and the first ore was crushed in October of that year.
Work continued thereafter until June, 1929. It was found that the former operator had stoped down to the 340-ft. level. The shaft was deepened to 2291 ft. and a great deal of prospecting work was done, but resulted in one disappointment after another. Only small lenses or faulted segments of ore were found in the main fault fissure (Moore vein system) which had been relied upon to furnish tonnage of the character mined by Nevills in the old operations. Several other veins were prospected from the Moore shaft without revealing ore.
The total production reported from the Moore from 1922 to 1929. inclusive, was 92,935 tons yielding $564,624.
Geology and Mine Workings
The ground embraced in the Moore options covered on the west a narrow band of Mariposa slate traversing greenstone in a northwest- erly direction, and on the east a complex of Mariposa and Calaveras slates, wider than the first belt of slates mentioned and parallel to it. The shaft is sunk on the easterly strip. The deeper work showed the Moore vein system, in and near the contact, badly broken by the contact fault. Ore was cut off about 750 ft. deep, and below there little ore was developed. Levels were opened at 640, 950, 1100, 1200, 1800, 1950 and 2100 ft. Small amounts of ore were found along the fault on the 1100-ft. north drift near the shaft and 500 ft. north of it. On the 1800-ft. level the Moore vein was found 170 ft. northeast of the station, and a length of 150 ft. gave some good assays, though it was not all of payable grade. This section was cut off on both ends by faults. When opened at 1500 ft. depth this shoot was found to be short. On the 1950-ft. level it was 50 ft. long by 8 ft. wide with an average value of $7 a ton, but was not found on the 2100-ft. level. The northwest drift on 1800-ft. level was run over 1200 ft. in search of further orebodies on the Moore vein, without success. The theories of several geologists as to the direction and amounts of movement of the supposed faulted orebodies on the dip and strike along the main fault were tried out
1 Knopf, Adolph, The Mother Ix>de System of California: U. S. G. S., Prof. Pap. 157, p. 70, 1929.
MOTHER LODE GOLD BELT 99
unsuccessfully. Several other veins which cross the property were given names to identify them with veins in other properties, of which they were presumed by the Moore operators to be extensions. These included the 'South Jackson,' 'Aetna,' 'Zeila' and 'Kennedy- Argonaut,' and prospecting crosscuts and drifts were run to and along all of them. On the 640-ft. level a drift was run on the 'Aetna' vein. On the 1800-ft. level a long crosscut was run westerly to the 'South Jackson' vein from the north drift. On the same level a crosscut was run 1800 ft. to the 'Kennedy- Argonaut' fissure, the latter occupying at the surface the narrow band of Mariposa slate first mentioned hereunder. None of these disclosed ore.
The net result of the venture was a substantial loss to stockholders.
New London {Lucille) Mine, adjoining the Plymouth on the south, had been worked to a depth of 1130 ft. in 1888, and no record is avail- able to show the production, probably because of the o^vners' refusal to give information. It was at that time part of a group covering 12,000 ft. on the Mother Lode. By 1890, the main shaft was 1340 ft. long on %o° incline and another shaft was 300 ft. long. The lower levels were run as follows :
1300-ft. level, 550 ft. south, 150 ft. north. 1200-ft. level, 630 ft. south. 1000-ft. level, 600 ft. south.
The 200-ft. and 300-ft. levels were also opened to work the upper ore-shoot. This shoot was reported 200 ft. long by 7 ft. wide. The lower shoot apexed at an inclined depth of 930 ft. and lay 400 ft. south of the shaft on 1000-ft. level but from what can be learned must have been short, as it seems to have been stoped for a length of only 50 ft. on that level.
After 1890, the property was idle until 1894 when the Lucille Mining Company reopened it and put up a 40-stamp mill, but shut down in a short time.
North Star, Mclntire, Boyson, Occident, Granite State and part of Beatrice claim were iinder option in 1926 and 1927 to California Mclntire Mining Company for which Fletcher Hamilton was agent.
A shaft about 1000 ft. deep on the North Star claim was unwatered to the 600-ft. level and considerable new work was done. The claims are on the Mother Lode north of Sutter Creek. The greenstone lies on the footwall, followed on the east by Mariposa slate containing the usual greenstone dikes or sills. Most of the work was done on the North Star and IMcIntire claims. The old work on the North Star, besides the shaft, included a crosscut southwest on the 600-ft. level and a drift 2500 ft. northwest into adjoining claims on a gouge and scattered quartz seams in the slate in search of a possible continuation of the South Spring Hill orebody, which is said to have occupied the same fissure. No ore was found.
The new work included a crosscut 100 ft. northeast to a contact of greenstone and slate with drifts 400 ft. each way on the contact, which was found to be frozen and barren ; the southwest crosscut was also extended 500 ft. farther, making it 800 ft. long. Here the footwall contact of greenstone and slate was prospected. Two gouge-filled fis- sures, 50 ft. apart, were encountered. Going in a northerly direction
100
AMADOR COUNTY
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\
MOTHER LODE GOLD BELT 101
from this crosscut for a distance of 550 ft., the face reached a point 180 ft. from where the bottom of the 200-ft. Mclntire shaft would have been, had this shaft been deepened. Southwest, these gouge-filled fis- sures were cut at several points, 400 ft. of new work having been done in that direction. The gouge and black slate showed only small scat- tered bunches and seams of quartz, and Roger Beals, who was superin- tendent, stated that assays showed nowhere over a few cents in gold, although it had been claimed that there was a prospect in the Mclntire workings, on the 200-ft. level. This work off the southwest crosscut prospected the Mclntire ground for 950 ft. The work on the hanging wall contact first mentioned prospected that contact on the east side of the North Star claim for 800 ft. Three crosscuts into the greenstone, each about 60 ft. long, developed nothing. The greenstone there is about 300 ft^ tliick. The old drift, 2500 ft. long, prospected the Boyson and South Keystone claims and a crosscut from it is said to have pros- pected part of the South Spring Hill claim.
Two conditions are noticeable in the workings on the 600-ft. level — first, the dryness of the ground, and second, the absence of any cross veins. The slate is plicated in small broken folds in places, and ground to gouge along the fissures with considerable quartz intermixed ; but the very low reported assays indicate that the absence of ore is not due to faulting. The gouge has so completely dammed the fissures that although considerable water enters the shaft from the surface, and a small stream also runs along the lode, the workings are dry away from the shaft.
The company quit work about the middle of March, 1927.
Old Eureka (Amador Consolidated or Eureka) Mine was opened in 1852 and the first mill, of 10 stamps, was erected the same year. The mention made of this mine by Dr. J. B. Trask in his report for 1855 is interesting. This refers to the Eureka claim.
"The whim shaft A has been carried from 7 to 16 fathoms during the past year. The adit enters from the west and is about 100 feet in length. The upper gallery has been carried south of the adit 114 feet, and north 75 feet. The level at the bottom of the 16 fathom shaft is 144 feet in length. The rocks are a graphic slate, very firm and often charged with pyritic crystals.
"The rich thread, which commenced at the surface, and for fifty feet in depth, was highly pyritiferous ; is found at the bottom of the main shaft much more pro- ductive. The pyrites have ceased entirely at this depth, and the hilo is composed of metallic gold, not disseminated, but forming a true vein, at times exceeding three-eighths of an inch in thickness. The vein has been struck in an adjoining mine about 1000 feet to the south. This is the only instance of a true vein of metallic gold having been found in this state."
The adjoining claim on the south was the Badger on which 10 stamps were built in 1854. A new 20-stamp mill was put on the Eureka in 1856 and 20 stamps more in 1857. Alvinza Hayward finally obtained control of both mines in 1859 and consolidated them. In 1867 the north shaft was 1230 ft. deep, middle shaft 960 ft. and the southern one 760 ft. deep. There were 56 stamps dropping in the two mills, crushing 80 tons a day, and ore was also sent to custom mills. Hay- ward, always secretive, refused to give details of production, but local report placed the output at $6,000,000 up to 1867. In 1866 it was said 30,000 tons had yielded $27 a ton at a working cost of $5 a ton. In March, 1868, the mine was sold for $750,000 to the Amador Mining Company. For 13 months ended October, 1868, the total yield Avas $566,945.92 or $21.88 a ton. For the year ended July 1, 1869 (over- lapping the last period) 30,361 tons yielded $617,542 or $20.34 a ton.
102
AMADOR COUNTY
3
H O
MOTHER LODE GOLD BELT 103
In 1870 the yield was $341,701 and in 1871, on account of a labor strike, only $201,357. For 14 months, December, 1872, to January, 1874, a total of 22,465 tons yielded $402,294 or $17.91 a ton. For 14 months ended April 1, 1875, the yield was $239,717 in bullion and $20,254 from concentrate, from 22,098 tons, indicating a marked drop in gold content of ore. In 1874 the 'boulder ledge' on the west of the 'true ledge' was being mined 30 ft. wide and was yielding $10 a ton on the 800 level. In 1875 it was evident from the superintendent's report that the upper shoot on the 'true ledge' was being bottomed at 1700 to 1750 ft. in depth. The shaft was continued as a prospect shaft to 1965 ft. At that time a large reserve of low-grade ore was claimed. Work finally stopped in 1881. A total of $12,000,000 to $13,000,000 seems a fair figure for the production during the 30 years of operation.
In 1916, a well-financed company bought the property and began unwatering it. The shaft was found in very bad shape on account of having been sunk in the Mariposa slate. It was deepened to 3500 ft. and levels were turned at 1700, 2125, 2950 and 3500 ft. and 1200-ft. level was reopened. On each of these except the lowest, from 1450-ft. to 1640 ft. of drifts M^ere run. A crosscut was run west 800 ft. on 3500-ft. level. All of this exploration failed to reveal ore that would pav under conditions then existing, and the work was stopped late in'l920.
In 1924 Central Eureka Mining Company purchased the Old Eureka holdings and have done considerable work in it since, although this was mainly incidental to the working of its principal orebody on the south line of the Old Eureka until 1930, when the lower levels of Central Eureka were abandoned. Since then, Old Eureka has been more actively explored.
Geology
The main vein was found to have had a slate footwall with heavy gouge and greenstone (altered andesite) hanging wall in those workings that had furnished ore. The andesite extends for 800 ft. on the strike, and the ore was stoped for 450 to 500 ft. on the strike and evidently gave out, both on dip and strike, with the thinning out of the andesite, about the 1700-ft. level. The shaft and most of the other workings between 1700 and 3500 ft. in depth were in Mariposa slate, which is soft and swelling ground. The andesite lens thinned out to such an extent that it was no longer a factor in controlling fissuring, and the vein so far as explored was for the most part a mass of barren or low- grade stringers in the slate between these levels. Wide veins of ]ow-grade quartz were coming in at the south faces of the 2950-ft. and 3500-ft. levels. The former level was run to the Central Eureka end- line. A number of crosscuts were run without striking ore, although many think that the possibilities in this exploration of the walls of the main vein had been far from exhausted when work was stopped. The longest crosscut was 800 ft. west on the 3500-ft. level. No ore of milling grade was found except a few small pockets.
The following are the positions of other veins with relation to the main Old Eureka vein.
104 AMADOR COUNTY
Central Eureka lowest ore-shoot is reported about 300 ft. west of Old Eureka vein at the common end-line at 3500 ft. in depth. Due to the direction of this end-line the length of the original Central Eureka claim along the strike shortened rapidly in depth. This vein was reported low grade where crosscut in the Old Eureka. As the later developments in the Central Eureka on this ore-shoot have been prin- cipally below the 3500-ft. level and have extended to date to 4850 ft. in depth, and several hundred feet north of their shaft, this is an example of the uncertainties of mining. The purchase of the Old Eureka prevented possible expensive litigation.
The Kailroad vein is about 500 ft. east of the main Old Eureka vein. It produced $70,000 to a depth of 340 ft., the reported grade of ore being good.
The Wolverine vein is probably a little in the footwall of the Old Eureka.
The Wildman-Mahoney vein and the Lincoln vein are several hundred feet west.
Original Amador Mine is said to comprise the first group of loca- tions made in Amador County on the Mother Lode. It was opened in 1852. At present it contains the Original Amador, East Amador, Amador Wedge, Great Eastern, Eclipse Extension and Last Chance claims, covering 4400 ft. on the Mother Lode. The geology and mine workings were described by James D. Hague in 1872, and his report is outlined in the next two paragraphs.
The underground workings extended 650 ft. northwest from the south boundary. There were three shafts, of which the south shaft was 175 ft. deep, the middle one, 196 ft. northwest from the first, was 356 ft. deep, and the third shaft was just started. The vein, having hanging and footwall seams, varied from one to 20 ft. wide, had a hard, slaty-greenstone hanging wall and black-slate footwall. The hanging-wall vein was usually the larger, was of hard, white quartz, frequently mixed with greenstone and sometimes joined to the green- stone of the hanging wall with no gouge nor well-defined limit between. The footwall vein was narrower, and in the black slate. It showed an abundance of clefts or crevices in which were seams of sulphurets and visible free gold. This vein was always the richer of the two, and was stoped in the old workings (above 356 ft. in depth), while the hanging wall vein was left. The veins at times were together, at times separated. Below the third level the vein pitched east into the greenstone, with 50 ft. of greenstone between the vein and the footwall slate.
A 40-stamp mill was completed in 1872, an English company having purchased the property. About 3600 tons of ore crushed yielded from $4 to $6.50 a ton, and the tailing loss was $2.50 to $3.26 a ton. This company spent considerably more than they took from the mine during the next two years, but no complete record of their work remains.
The later work by Original Amador Consolidated Mines Company began in 1908. The property was one of the smaller producers of the lode until 1918, since which year it has lain idle. The production between 1910 and 1918 was between $90,000 and $130,000 a year. The operations were profitable in spite of the general low gold-content of ore, and permitted the purchase of the claims adjoining the Original
MOTHER LODE GOLD BELT 105
Amador. From 1909 to 1915 a mill of twenty 1000-lb. stamps and 8 Deister concentrators was operated. This had a capacity of 90 tons a day. The ore crushed during this period came largely from, develop- ment work and averaged $3.44 a ton with a reported average operating cost of $2.56 a ton.
In 1915 the capacity of the mill was trebled, with the installation of two 8-ft. by 3-ft. Hardinge mills, classifiers, etc. There was some falling off in average grade of ore thereafter. A large tonnage of low- grade ore was claimed to have been blocked out. About this time some landowners began to complain of alleged damages to their land from tailing and in some cases to demand payment therefor ; and in 1917 the California Debris Commission addressed protests to several mine own- ers about tailing entering streams. Both the Keystone and Original Amador companies were put under bond in June, 1917, in this connec- tion. The latter closed in 1918 after having made a greater production in 1917 than in any previous year. The last full year's output was low grade.
Mine Workings and Geology
The mine is opened by an inclined shaft 1238 ft. long with 9719 ft. of drifts, 7023 ft. of crosscuts and 27,465 ft. of raises. The geology of the upper section has already been mentioned. The main vein left the contact of Mariposa slate and greenstone and entered the greenstone about the 300-ft. level and assumed a much flatter dip below there. The shaft, which had followed the vein to 300 ft., was in the footwall of it below there, and also in the greenstone. The ore on the hanging wall vein below the 300-ft. level was partly from the vein itself and partly altered greenstone lying on the hanging-wall side of the quartz. The vein proper is said to be 15 ft. thick or more, and because of its flat dip showed a width on the level up to 90 ft. according to Knopf. East of this vein, parallel veins of 'gray ore' consisting of quartz stringers and altered greenstone, have yielded ore. According to Tucker, these are from 12 to 20 ft. wide. As the mine was not visited by a representative of this division between 1914, when the shaft was 780 ft. deep, and the time of closing in 1918, the details of geology below there are not at hand.
The footwall vein which was chiefly worked in the earlier oper- ations on the upper levels is reported narrower and better grade than the main vein, which it joins north of the shaft. It is a stringer lead in slate, 6 to 8 ft. wide.
In the main vein shrinkage stoping (top slice and fill) was used because of the firm walls and width of ore, and this, with the moderate depth, permitted low-cost operation.
The mill made a recovery of 90%. Concentrates formed from li% to 2^% of ore. They ranged from $40 to $75 a ton in value and contained usually from one-third to one-half of the gold.
Little stoping was done below the 700-ft. level, the ore milled from below there having come from drifts and raises run in the course of development work. The 700-, 800- and 1200-ft. levels were each run several hundred feet north and south of the shaft, it being claimed that low-grade ore is exposed for a length of 1000 ft. on the 700-ft.
106 AMADOR COUNTY
level. This leA^el corresponds nearly in elevation with the 800-ft. level of the Keystone.
The work of unwatering the Original Amador was started in August, 1934. It is reported that the same company may also take over the Bunker Hill Mine, adjoining on the north.
Pioneer Mine adjoins the New London on the south about one-half mile south of Plymouth, and like the latter lies about midway in a mile-wide area of Mariposa slate. The period of principal activity appears to have been in the middle 1890 's, when the largest recorded annual production was $15,000. The shaft was 550 ft. long on an incline of 60° and five levels were turned, 100 ft. apart.
It contains two veins, the east vein of massive quartz and a west vein of banded quartz which is said to have contained the best ore. The shaft was sunk on the latter. "While some good ore was produced in the upper levels, it is said that in the bottom the quartz was low grade.
Plymouth Mine
The holdings include the Southerland, Oaks and Pacific, Simpson and Aden, Reese, Phoenix East, Plymouth, Phoenix Mill site, Reese and Woolford, fractions of the Indiana, Rising Star, Conville and lode claim 5181, the Beta claim and 22.77 acres of other land, a total of 126.3 acres, all in Sec. 11, T. 7 N., R. 10 E. Most of the ore was produced under the Simpson and Aden and Oaks claims.
History
The claims forming the present Plymouth Mine were originally taken up in 1852. The Southerland, Simpson and Aden claims were known as the Phoenix Mine, which was opened in 1859. Up to 1875, this had been worked steadily and in the latter year had two shafts, 200 ft. apart and each 900 ft. deep. Ore occurred in a ''large body of low-grade quartz" and was worked at a cost of $5.50 a ton. Soon afterward the Phoenix holdings were sold to the Empire Com- pany, and by 1879 the shafts now called the Empire north and south shafts, were'l200 and 1280 ft. long, respectively, or 1020 and 1100 ft. deep vertically, where sinking stopped. Ore averaging $9 a ton was then being mined between the 1000-ft. and 1100-ft. levels, on the main Empire ore-shoot. The North Empire ore-shoot was found in 1881 in a drift run north on the 900-ft. level, and was stoped from the 900-ft. to 1200-ft. level.
The Pacific vertical shaft (which became the main working entry in later years) was started in May, 1880, and was 1000 ft. deep by October, 1880. The southward rake of the main Empire ore-shoot carried it under the Oaks claim of the Pacific Mine, where it was mined by the Empire Company. The resulting lawsuit was won by the Pacific Company, and this led to the consolidation on June 1, 1883, under the name of Plymouth Consolidated Mining Company. The Woolford shaft was sunk 400 ft. deep in 1885.
The production of these mines prior to consolidation was reported about $2,500,000. Soon after they were grouped, the property became the principal producer of the county. As many as 147 stamps were operated by water power. From June 1, 1883, to January 1, 1888,
MOTHER LODE GOLD BELT 107
the company produced $3,804,499 from which 55 dividends totaling $2,200,000 were paid. On January 24, ,1888, a fire was reported on the 1200-ft. level and was not finally reported as being extinguished until the mine was flooded. This fire is alleged by some to have occurred just when good ore appeared to be giving out. The Pacific workings were reopened in 1889, and in the four years following pro- duced $215,518. From the above figures it would appear that the total l)roduction by the old companies up to the complete r>essation of work in 1892, was "^$6,520,017. In a report by Albert Burch in 1911. it was stated, however, that the old companies up to 1891 produced $7,123,- 009.56 from 877,000 tons with a net profit of nearly $3,000,000 and that bullion produced amounted to $6,659,079.11, the balance pre- sumably having come from concentrate and tailing. Between 1898 and 1902, about $44,000 was produced from the old tailing dumps.
The mine lay idle from 1892 to 1911, when the Pacific shaft was reopened and a winze was sunk from below the 1600-ft. level to 2000 ft., developing ore enough to result in the formation of Plymouth Con- solidated Mines Company, Limited, in London, with a capital of 240,000 shares of one pound sterling ; 204,482 pounds sterling was paid for the property. From August 1, 1914, to the end of 1924, a total of 1,037,373 tons of ore was milled and yielded $5,718,889. Dividends paid from these later operations amounted to $758,000. After 1920, however, the cost of operation increased until it equaled or at times exceeded yield. In February, 1925, the mine was forced into receivership to protect a local loan, and was sold to Argonaut Mining Company. The workings had by that time reached an inclined depth of 4300 ft. (the shaft below 1600 ft. having been turned to an incline of 60°.) The principal known orebodies had been worked out to this depth.
Argonaut iMining Company sank the shaft from the 4300-ft. level to the 4450-ft. level and milled some ore which added $515,292 to the production, from 1925 to 1928, inclusive. They decided, however, not to appropriate the sum needed to put the mine in proper shape and sink another 150 ft. The only work done since 1928 has been some prospecting on the upper levels, which stopped in 1931. Taking the larger of the figures quoted for production prior to 1889, the Plymouth holdings have produced $13,357,190 from 2,029,710 tons of ore. From this, if we estimate dividends of $750,000 for the operations prior to June 1, 1883 (when ore of much better grade was handled than later) the total dividends were about $3,700,000 or nearly 28% of total pro- duction.
Geology
The Mariposa slates at Plj^mouth are a mile in widtli and it is entirely within these slates that the paj'able ore has been found. On the east, the Mariposa formation is separated from an outlier of one of the granodiorite domes of the Sierra Nevada batholith by a strip of amphibolite schist only one-fourth mile wide. This schist has been referred to tlie Calaveras formation (Carboniferous), and it is believed to have been originally andesite. The andesite cut in some of the mine workings is believed to have had an important influence on the position of ore. Some sandstone, formed of chert fragments, and some con- glomerate are found in the Mariposa formation, but it is typically a
108
AMADOR COUNTY
3,655' LEVEL
„r.' tf-r(5)t30a Ml»'lQ)i36/iO. ^)»-!>)t (G) 45 60
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ii*-'^ 4'iatl360
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3WTi285
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,0 0 lfe(Q>t380Q lfe'-3!^(Q)tl2(0. 3i^7)^((tltll60 ' 7<^'lS>in20 ,
0-3tf(a'tZ7.60 3lt-6felQ)»600
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Distribution of gold and structural features of typical quartz vein inclosed in slate, Plymouth Mine. Reproduced from U. S. G. S., Prof. Paper 157, p. 28. Geology by Robt. J. Duncan.
MOTHER LODE GOLD BELT 109
black, carbonaceous clay slate with small iutrusious of basic igneous rocks and beds of clastic volcanic material which originally were spread out as mud flows of andesite or similar volcanic ash on the ocean floor at the time the Mariposa beds were being deposited. The present dip of the schistosity of the slate is nearly vertical, but unlike the usual dip in most sections it is to the west. Though tilted and telescoped, and rendered slaty by pressure, the Mariposa beds are other- wise little changed.
The Calaveras formation (Carboniferous) on which the Mariposa beds rest, is another complex of altered rocks, which were in part originally sedimentary and in part igneous. All the members of this formation have been intensely altered and the igneous members have been so completely changed both in physical structure and chemical con- tent that they are now greenstone schists, locall}^ called amphibolite schist. Malcolm Maclaren regards the contact between the Mariposa slate and the amphibolite schist on the east as a fault contact, dipping east at an angle of probably about 60°.
The Veins and Ore-Shoots
Three systems of lodes have been found, comprising main veins and spurs, and called the Empire, Reese and "Woolford and hanging-wall contact veins. The most important, the Empire, is believed to occupy a fissure opened by a reverse fault, on the footwall side of the mine. In the deeper levels it is the tj'pical slate-quartz stringer leads or 'ribbon rock' of the lode. This is the vein opened in the Phoenix workings and followed to a depth of 1200 ft. in their old shafts prior to consolidation. It does not outcrop prominently except on the New London claim. Its strike is generally north and dip 62° east, cutting across the schistosity of the slate at a small angle in dip and strike. The Phoenix or Empire ore-shoot was in this vein, having its apex in the Simpson and Aden claims. It raked at a flat angle, 40° to 50°, to the south, and this carried it into the Oaks claim which was being worked by the Amador Pacific Company through the Pacific shaft. From the surface to about 400 ft. it was of only average grade, and from there to 1000 ft. even lower, so that between 600 ft. and 900 ft. much of it was left unstoped. From 1000 ft. to 1500 ft. it was richer, and in 1886 out of a gross production for nine months of $447,547.13 there was a profit of $254,402.13 above operating expenses, and divi- dends of $225,000 were paid. The ore-shoot was claimed at that time to be 800 ft. long. The 1500-ft. level was just being opened and no ore had been stoped there ; but it is not certain if the 800 ft. in length referred to the Empire shoot alone, or to the combined length of it and the Pacific ore-shoot. The vein was reported averaging 30 ft. wide and containing 1^% of concentrate worth $135 a ton. The average value of this ore was $6 to $8 a ton. In the upper levels this ore-shoot was 450 ft. in horizontal length. It is said to have lain on the footwall down to the 1000 ft. level, and below that on the hanging wall. Pacific vein is considered as a spur of the Empire leaving it a little north of the Empire north shaft and striking a little east of south to near the Indiana shaft, where the Indiana vein has the appearance of a hanging-wall spur. Maclaren connects this vein with the New London. Three ore-shoots were worked in tlie Pacific between the
no Amador county
1600-ft. level and 835-ft. level, above which they are said to have died out. All three were on the south side of the Pacific shaft. Their occurrence is attributed to the junction of the two veins. They rake toward the Empire shoot, and the vein in which they lie dips 80° E., so that the Pacific and Empire shoots merged about the 2000-ft. level. Below there the rake of the ore becomes perpendicular. No details are at hand regarding the Pacific operations, but some interesting items were observed when the shaft was unwatered in 1912.
Main Ore-Shoot in Depth
From the 1140-ft. leve}, ore had been stoped for nearly 200 ft. in length and the back gave an assay of $19.34 over a width of 41 inches. On the 1600-ft. level, a vein 16 ft. wide was exposed in the old work- ing, but it was too low-grade to make ore. This drift was extended south. Finally, ore 5 ft. wide was developed for a length of 255 ft. and with an average value of $6.96 a ton on this level. On the 1850-ft. level, the ore-shoot proved to be 334 ft. long, with an average width of 4^ ft. and average value of $6.32 a ton. There was a heavy post- mineral gouge on the hanging-wall side on this level. Below there, the orebodies decreased in size but held up in value to about the 2450-ft. level. From there to the 3050-ft. level, the main vein was poor or unpayable, and was also disappointing between the 3235- and 3650-ft. levels. From the 3400-ft. level about 380 ft. north of the shaft, a winze was sunk and in 1922 struck ore which developed a stope length of about 100 ft. to 180 ft. and a thickness up to 9 ft. Some 20,000 tons of ore mined from this ore-shoot averaged $10 a ton. In the workings above 3835- and 2925-ft. levels this ore was crushed 'ribbon rock' with gouges on both walls varying from a seam to 1| ft. in thickness. In the 3925-ft. level it showed 9 ft. of ribbon quartz, broken and sugary in texture from faulting, and containing visible gold in places. In spite of the good grade of this ore, the expense of working through the winze was too high to permit a profit. The shaft was eventually sunk, after this ore had been mined.
The Reese and Woolford vein has not contributed payable ore. A shaft was sunk on it to a depth of 400 ft. in the 1880 's. The Chicago or hanging-wall contact vein likewise has no productive history here.
The Indiana vein, hy some regarded as a cross vein cutting off the Pacific vein on its southward strike and by some as a spur from the latter, has a shaft connecting with the 950-ft. level of the Pacific shaft, nearly 1000 ft. south of the latter. Part of the Pacific south ore-shoot was worked through this Indiana shaft which is kept equipped now with a hoist.
The ore in the Empire ore-shoot has always been bounded on the north by a meta-andesite dike entering from the footwall side. This outcrops 2850 ft. north of the Pacific shaft, and had a thickness of about 100 ft. where crosscuts have passed through it. The gouge and ore stop at this dike which persists to the greatest depth yet reached. In the lower levels the andesite turns away from the shaft on a curved course indicating that it may be lens-shaped. On the 4450-ft. level the northern end of the orebody is now 800 ft. north of the main shaft.
Ore-shoots appear to have occurred at and near vein intersections or the junctions of spur veins. Contact zones between the slate and
PHYSICAL SCIENCES LIBRARY UNIVERSITY OF CALIFORNIA DAVIS, CALIFORNIA 95616
WALTER W. BRADLEY, STATE I
Manposd (Jurassic) C/ay S/a^e
■:;:;:;:;:;:;:;:i fmp/re Locfe Ore Shoofs.
>' Afp//7G Ancfesffe Df^e or 5///.
MOTHER LODE GOLD BELT 111
interbedded andesites seem to have been a controlling factor in determining the location of veins, as well as of ore-shoots. The acci- dental occurrence of open spaces in the main fault fissures or adjacent spurs was another factor.
Equipment
Some of the equipment for mining and milling formerly in use has been removed or has deteriorated, but larger items are intact. These include 30 stamps, 4 Hardinge mills, Nordberg hoist with 500 h.p. motor, 3 compressors with motors of 400, 75 and 160 h.p., respectively, steel head-frame, rock breaker, 3 air receivers, 7 transformers, about 20 electric motors, timber framing equipment, drill sharpener, etc. The hoist building and some others are in good shape, but the mill is not. There are 5 dwellings belonging to the company. The method of ore treatment has often been described and is alluded to under Metal- lurgy.
Seaton (Peerless) Mine, a mile east of Drytown and adjoining the Maryland on the south, covers 1260 ft. along the east side of the lode, in the strike of the Loyal Lead. Previous to 1868, the Seaton had been opened to a depth of 500 ft. and it was stated had produced 10,000 tons of ore that yielded $9 a ton. The 40-stamp mill was later burned and the mine lay idle for many years; in two later short periods of activity it was reopened and the shaft was sunk to a depth of 950 ft. on an incline of 65° and a length of 600 ft. was prospected. Another shaft was sunk 500 ft. There is no record of further production, though the total up to 1885 is claimed to have been important. The vein at the surface has a Mariposa slate footwall and greenstone hanging wall. On the 800-ft. level the width was reported two ft.
South EureJia Mining Company owns 401 acres, including practi- cally all mineral rights between the Kennedy and the Central Eureka and covering the Oneida and South Eureka Mines.
History and Production
The Oneida was one of the richest of the early-day producers. The ore on the hanging-wall side was the best, yielding $30 to $40 a ton, according to J. Ross Browne.^ The average yield in 1867 was $22 a ton and in 1868 it was $16 a ton.- In 1871 there were three shafts, 300, 700 and 800 feet deep, respectively. The vein was drifted for a length of 800 ft. on the 700-ft. level, and the ore-shoots were said to have been 700 ft. and 400 ft. long. These old workings finally reached a depth of about 1000 ft., after which the property lay idle until 1896. In that year a new vertical shaft was started and it was expected this would strike the vein at a depth of 1750 ft., but on account of the vein assuming a steeper dip, it was not struck until the 1900-ft. level. This shaft reached a depth of 2280 ft., and an inclined winze was sunk 250 ft. deeper at a point 280 ft. north of the shaft. The mine was worked extensively from the 1200-ft. to the 2200-ft. level. On the 1200-ft. level, the vein was drifted 2700 ft., on the 1500-ft. level 2050 ft., and on the 2000-ft. level about 2300 ft. Ore was stoped from the latter
1 Mineral Resources of the U. S., West of the Rocky Mountains, 1868.
2 Raymond, R. W., Mineral Resources of the U. S., West of the Rocky Moun- tains, 1869.
MOTHER LODE GOLD BELT 111
interbedded andesites seem to have been a controlling factor in determining the location of veins, as well as of ore-shoots. The acci- dental occurrence of open spaces in the main fault fissures or adjacent spurs was another factor.
Equipment
Some of the equipment for mining and milling formerly in use has been removed or has deteriorated, but larger items are intact. These include 30 stamps, 4 Hardinge mills, Nordberg hoist with 500 h.p. motor, 3 compressors with motors of 400, 75 and 160 h.p., respectively, steel head-frame, rock breaker, 3 air receivers, 7 transformers, about 20 electric motors, timber framing equipment, drill sharpener, etc. The hoist building and some others are in good shape, but the mill is not. There are 5 dwellings belonging to the company. The method of ore treatment has often been described and is alluded to under Metal- lurgy.
Seaton (Peerless) Mine, a mile east of Drytown and adjoining the Maryland on the south, covers 1260 ft. along the east side of the lode, in the strike of the Loyal Lead. Previous to 1868, the Seaton had been opened to a depth of 500 ft. and it was stated had produced 10,000 tons of ore that yielded $9 a ton. The 40-stamp mill was later burned and the mine lay idle for many years; in two later short periods of activity it was reopened and the shaft was sunk to a depth of 950 ft. on an incline of 65° and a length of 600 ft. was prospected. Another shaft was sunk 500 ft. There is no record of further production, though the total up to 1885 is claimed to have been important. The vein at tlie surface has a Mariposa slate footwall and greenstone hanging wall. On the 800-ft. level the width was reported two ft.
South Eurelia Mining Company owns 401 acres, including practi- cally all mineral rights between the Kennedy and the Central Eureka and covering the Oneida and South Eureka Mines.
History and Production
The Oneida was one of the richest of the early-day producers. The ore on the hanging-wall side was the best, yielding $30 to $40 a ton, according to J. Ross Browne.^ The average yield in 1867 was $22 a ton and in 1868 it was $16 a ton.^ In 1871 there were three shafts, 300, 700 and 800 feet deep, respectively. The vein was drifted for a l^^ngth of 800 ft. on the 700-ft. level, and the ore-shoots were said to have been 700 ft. and 400 ft. long. These old workings finally reached a depth of about 1000 ft., after which the property lay idle until 1896. In that year a new vertical shaft was started and it was expected this would strike the vein at a depth of 1750 ft., but on account of the vein assuming a steeper dip, it was not struck until the 1900-ft. level. This shaft reached a depth of 2280 ft., and an inclined winze was sunk 250 ft. deeper at a point 280 ft. north of the shaft. The mine was worked extensively from the 1200-ft. to the 2200-ft. level. On the 1200-ft. level, the vein was drifted 2700 ft., on the 1500-ft. level 2050 ft., and on the 2000-ft. level about 2300 ft. Ore was stoped from the latter
1 Mineral Resources of the U. S., West of the Rocky Mountains, 1868.
2 Raymond, R. W., Mineral Resources of the U. S., West of the Rocky Moun- tains, 1869.
112 AMADOR COUNTY
level to the old workings. A GO-stamp mill was used. Operations con- tinued until 1913, since when the mine has lain idle except for some work done through the South Eureka shaft.
Only fragmentary figures are at hand for the earlier production. For eight months prior to June 1, 1867, a yield of $135,000 from 7710 tons of ore was reported, at a cost of $5 a ton. For less than four months in 1868 the output was $60,400 from $16 ore. The mine at that early date had 60 stamps ; 40 weighed only 450 lb. each and 20 were of 650 lb. weight. By 1872 the average yield had dropped to $10 a ton.
For the period from 1898 to 1910, inclusive, the production was about $1,500,000. The yield during this time was from $2 to $3.75 a ton. The total production before sale to the South Eureka Mining Company has been estimated at $2,500,000.
The South Eureka lay undeveloped until 1891, due probably to the fact that most of the surface along the course of the Mother Lode fissure through the property is covered by andesite cobbles. In that ^''ear an inclined shaft was started which finally reached a depth of 2785 ft. To a depth of 900 ft. the fissure was filled principally with crushed slate and gouge, containing only a little quartz. The ground was very heavy and the shaft expensive to keep open on account of having been sunk in this crushed slate. On the 900-ft. level, a crosscut revealed some ore on the east contact (hanging wall) of black slate and green- stone, but for the most part the ore was scattered in bunches in the gouge-filled fissure and did not make a good-sized or profitable ore-shoot. For ten years assessments were levied to continue prospecting. During this period a 20-stamp mill was in use part of the time. After 58 assessments had been levied and the 2740-ft. level had been reached, a crosscut to the footwall encountered an important ore-shoot. This was subsequently developed by crosscuts from the higher levels, and was stoped up to about the 2000-ft. level. The mill was increased to 80 stamps and the property for several years was one of the largest producers of the county, employing from 200 to 250 men. They quit in 1918.
In 1921, the Central Eureka Mining Company took an option on the property and extended several of their deeper levels into the South Eureka. The 3350-ft. level south drift was run to a point 120 ft. north of where the South Eureka shaft would be if continued. A west crosscut was run in greenstone near the north end-line of the South Eureka on this level. On the 3900-ft. level, the drift was extended about the same distance into the South Eureka, and a crosscut was run east in slate 740 ft. This cut several gouge seams and vein formations but no ore was found. The 4100-ft. level was also run into the South Eureka. The result of all this work was disappointing.
Since the South Eureka Mining Company quit, the shaft as far far down as the 2740-ft. level, and the workings connecting the two mines on that level (Central Eureka's 2540-ft. level) and on the 1800-ft. level (Central Eureka's 1600-ft. level) have been kept in repair by the Central Eureka Mining Company. Water from the lower part of the Central Eureka Mine is pumped to their 2540-ft. level and piped thence to the South Eureka pump station which is maintained and operated by the Central Eureka Mining Company. The South Eureka shaft,
MOTHER LODE GOLD BELT 113
over wliich the hoist is kept in running order, also serves as a second exit.
From 1895 to 1908, inclusive, the property was only a moderate producer from the small orebodies of the hanging-wall vein. This ore ranged from $2 to $6 a ton in yield and the total output was about J^l,200.000 for this period, representing the exploitation of the hanging- wall vein from the 900-ft. to 2700-ft. level.
Following the discovery of the footwall vein system in 1908, the mine at once became an important producer. The 20-stamp mill not prov- ing sufficient, at first 10 stamps of the Central Eureka Mill were rented, and then the South Eureka mill was increased to 80 stamps. Dividends began in 1909 or 1910. There was a gross production of about $4,100,- 000 from over 980,000 tons of ore from 1909 to the time of closing in 1917. The total amount of dividends is not known, but if local reports are to be relied upon, must have been about $1,000,000. Operating costs were relatively low. In 1911 mining and milling cost was said to be $2.63 a ton and monthly dividends of $21,000 were reported. In 1915, operating cost per ton milled was $3,275 and dividends for the year were said to be $125,354.
Geology and Mine "Workings
On account of the outcrop of the lode being covered on the South Eureka by the capping of an ancient stream channel, the surface gave little encouragement for quartz prospecting. The sinking of the shaft was therefore a speculative venture, based on the position of the claims between known producers on a well-defined gold-bearing structure. Two lines were surveyed across the property following the direction of strike of the lode as exposed in the Eureka mine on the north and in the 1650-ft. level of the Kennedy on the south. These proved to be about parallel and 100 ft. apart on the surface of the South Eureka. Midway between the lines an inclined shaft was started in the black slate which was soft, crushed and hea^'y. It proved to be expensive to keep open, requiring continuous retimbering and realigning. Cross- cuts were run to the hanging-wall greenstone at 500, 600 and 900 ft. inclined depth. The work to a depth of 900 ft. gave little ore, as previously noted. The crosscut at 900 ft. showed an ore-shoot up to 5 ft. wide at the contact. The greenstone on the hanging-wall side of this had been sufficiently mineralized to become ore, and on the footwall side of the vein there was also a "rich pay streak from 1 inch to 10 inches in width, heavily sulphuretted and high grade." In 1900 the shaft had reached 1800 ft. in length. The vein was reported much disturbed by faults, with rich ore occurring in bunches in the slaty gouge.
The beds of Mariposa slate in which the ^Mother Lode occurs here lie between two belts of greenstone. The shaft cut the hanging wall vein at the 1700-ft. level and followed it to the 2000-ft. level, near which this vein entered the greenstone and the shaft passed into the slate. The slate belt is several hundred feet wide. The so-called footwall vein is one of several worked in the lower levels. It was found by following a spur or link vein from the contact region into the slate where it joins the footwall vein which is about 250 ft. west of the
8 — 4156
114 AMADOR COUNTY
contact. It was followed upward from the 2740-ft. level to above the 2000-ft. level.
In winzes and drifts below the bottom of the shaft it was found the main ore body was only 60 ft. long on the.2900-ft. level. It raked north and crossed the line into the Central Eureka on the latter 's 2700-ft. level, but went only 30 ft. below there.
The mill contained eighty 1,150-lb. stamps, dropping 6^ inches 100 times per minute and crushing five tons each daily through 24-mesh screen. After outside amalgamation, the pulp passed to 48 six-ft. Frue vanners. The saving was from 85% to 91%. Concentrate formed from 1.7% to 2% of the ore, and carried from $60 to $72 a ton in gold and 40 to 65 cents in silver. •
South Jackson Mine, one-half mile south of Jackson, was worked by a company of the same name from 1912 to 1915. It is on an agricul- tural patent (Meek Ranch) covering part of the eastern band of Mother Lode slates. Three stringer leads were prospected. A vertical shaft was sunk 577 ft. with levels at 210, 345 and 500 ft. On the 210-ft. level a crosscut was run 90 ft. west. On the 345-ft. level a west crosscut 280 ft. long cut a vein 80 ft. from the shaft, and this was followed north 312 ft. and south 383 ft. showing 5 ft. of quartz in each face. On the 500-ft. level a crosscut was run 1035 ft. east cutting the middle vein 20 ft. from the shaft ; this vein was drifted on 260 ft. north and 130 ft. south. A vein which they called the Zeila was struck in this crosscut 750 ft. east of the shaft and a drift was run north 100 ft. on it.
In January, 1915, South Jackson Mining Company announced they had spent $104,000 but were disappointed with the results of their work, as the amount of ore found did not justify a plant. After crush- ing less than 200 tons of ore at a custom plant that year, they closed the property which has since been idle.
South Keystone Consolidated Mining Company. This was the company which did considerable work in 1917 and 1918 on the North Star (which see), Boyson and South Keystone claims. They made no production.
Valparaiso Mine is on a narrow strip of Mariposa slate enclosed in the greenstone and extending from the Argonaut Mine to Spanish Gulch where it joins the main slate belt. The mineral zone along this slate and its contacts is locally called the 'black metal belt' because the gold is coated black and possibly because of the rich sulphides, often carrying much more gold than usual on the lode. The Mammoth Mine adjoins on the south. The gold occurrence is pockety.
An adit 1300 ft. long was completed on the Valparaiso claim in January, 1888, and the three men who drove it were each given a one-twelfth interest in the claim for their work. It extended to within 200 ft. of the south line. A Huntington mill was put on the claim the same year. It was thought at the time that a rich and well-defined ledge lay in the hanging wall of this adit. The later production, how- ever, was in the form of small tonnages of fair to high-grade ore. No record is at hand of the first ten years' output after 1888. From 1898 to 1931, inclusive, the Valparaiso is credited with a production of over $100,000. The estimated value per ton of the ore milled ranged from $9 to $500, as much of the gold came out in the form of 'pockets' or
MOTHER LODE GOLD BELT 115
'specimens' and the ore crushed was the residue mined in cleaning up around such bunches. Some winze workings and exploratory cross- cuts were driven in later years. The concentrates from this mine are reported to have carried at times as much as 37 ounces of gold per ton and formed 5% to 6% of ore.
The geology is very similar to that of the Amador Queen No. 2 and Mammoth Mines.
Zeila Mine (originally called the Coney) is at the southeast side of Jackson, and the original mining claims with mineral rights acquired on ranch lands cover a mile along the contact of greenstone and Cala- veras schist.
In the 1860 's it had been worked to a depth of 200 ft. and for 300 ft. on the strike. There was a 16-stamp mill in 1867 and the ore at that time was said to be yielding $13.50 a ton, of which $6 a ton was said to be in free gold. A chlorination plant had already been erected to treat concentrate, which was said to form 5% or more of ore. By 1875, however, after a depth of 600 ft. had been reached, work had been stopped and the mill had been dismantled, because of * ' refractory rock." It was reopened about 1880 and was a producer every year until 1914, since which date it has lain idle and has passed into the possession of the Kennedy Mining and Milling Company.
Few details were ever given out concerning the results of operation and as is natural in such cases the output of the property has been overestimated. Because of the low grade of ore and the size of ore- body, there was a certainty of performance which made for low cost of operation, and if the figures for the Zeila were obtainable, they would probably prove as low as, if not lower than any others for operation at any considerable depth on the Mother Lode. W. F. Detert boasted that although the Zeila was never even a $4 proposition (during his time) it had been a steady dividend payer ever since it was placed under his management. The output was about $5,000,000 for the 34 years ended in 1914, and in the later years at least, the average recovery was between $3 and $4 a ton. The stock was closely held and the amount of dividends was never revealed. A 40-stamp mill was operated most of the time.
Geology and Mine "Workings
No reports on the mine have been printed since about 1900. In 1890, Fairbanks stated (Report X of the State Mineralogist) that
"At the Zeile there are several veins worked. The hanging walls are usually of decomposed dikes. The character of the rock worked Is somewhat similar to that of the Amador Queen — alternations of gray slates, small veins, and a decom- posed crystalline rock. The whole of the rock is filled with stringers of quartz and the greater part of it is milled. The gouge on the footwall of the main vein of the Zeile varies from a few feet to fifty feet. There is no gouge on the lianging wall, and the horse is always from that wall. The best paying portion is the ribbon quartz."
According to Folio 63 of the U. S. Geological Survey,
"The vein is essentially a stringer lead in amphibolite schist and has a general dip of 50° to 60° E. It is separated from the black slates (Calaveras formation) of the footwall by a hea\'y gouge. The width of the vein where sloped is 40 to 50 feet, but the general average is somewhat less. A fine-grained, altered dike, from 4 to 6 feet wide, probably originally a diorite, accompanies the vein. The ore is of low grade — less than $4 per ton. Pyrite is the principal sulphide, but there is sometimes a little molybdenite, and small quantities of galena and zincblende are said to occur and to indicate good ore. Calcite is quite abundant, both as stringers and crystal- lized with the quartz."
116 AMADOR COUNTY
The shaft was sunk 1700 ft. on an incline of 65°. The 1570-ft. level drift was run nortli 3000 ft., and on that end a winze was sunk 458 ft., with levels at 157 and 295 ft., which were also drifted north, the latter 450 ft. At the time of closing it was stated the mine con- tained 360,000 tons of ore averaging less than $4 a ton. It was stoped out from the 1200-ft. level to the surface, north of the shaft, where the ore-shoot was 600 ft. long and averaged 20 ft. wide.
The mill of 40 stamps in the most productive years crushed from 60,000 to 65,000 tons of ore annually with an annual output that only once exceeded $200,000. The concentrate formed from 2% to 2.3% of ore, and yielded from $68 to $93 a ton. This concentrate carried from one-half to over tw®-thirds of the gold, and was treated by chlorination at the property.
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CALAVERAS COUNTY
Geology.
The most productive sections of the Llother Lode in this county are the ones extending from Stanislaus River to the north slope of Carson Hill, and that within the townsite of Angels Camp. In the first, the ores occur in or near altered intrusives occupying contact areas between the amphibolite schist and the Calaveras formation. At Angels Camp the mines were found in profoundly altered and silicified amphibolite schists. (See Utica and Gold Cliff Mines.) The more important mines of Angels Camp were all in a block of country bounded on the north by a fault crossing the course of the lode and dipping southeast. West and northwest of Angels Camp, mineralization occurs over a width of more than two miles, in which many small mines but 5^0 large orebodies have yet been ft)und. Characteristic of this zone are 'stringer leads' of quartz and calcite, with occasional pockets, in amphibolite schist. A few miles northwest of Altaville, there is a group of small mines in the Calaveras slates which show well-defined veins. Among these are the Shotgun, Demarest and Thorne. From Altaville to the vicinity of San Andreas mines and prospects are scattered along a northwestward course in amphibolite schist. It is not until the Gwin Mine is reached, near the northern end of the county, that the lode re-enters the Mariposa clay slate. This mine is on the extreme west side of the slate belt, in a lens of slate about one-quarter of a mile wide, with altered andesite on both sides, and is similar geo- logically to the important mines at Jackson and Sutter Creek.
Mokelumne Hill district, which is at the southeast end of a batho- lith of diorite with an area of about six square miles, is east of the course of the Mother Lode, but has many quartz mines, some of which have been important producers.
Geography, climate, water, power, timber.
Calaveras shares with the counties north and south a gently rolling topography in the Mother Lode section. There are no important streams crossing the lode between the north and south county-lines, which are formed by the Mokelumne and Stanislaus Rivers respectively. Occupying as they do, deep canyons w^hich they have cut transversely across the course of the Sierra Nevada 's western slope, they have neces- sitated expensive installations for water and hydroelectric power sup- ply. Carson Hill, the principal outstanding topographic feature of the lode in this county, rises to an elevation of about 1900 feet, over 1100 feet higher than Stanislaus River which flows by it on the south. This hill and Chaparral Hill owe their heights to the resistant character of the massive 'bull quartz' outcrops so common farther south. Else- where the lode traverses rolling land carrying sparse digger pine, small oaks and some brush.
Angels Camp, elevation 1535 feet, has a rainfall varying from 20 to 54 inches annually, most of this falling as a rule between November first and May first. Orange trees have grown and borne fruit for many
126
CALAVERAS COUNTY
years at Mokelumne Hill, 1550 feet elevation, where the mean minimum temperature over a period of 17 years never dropped below 36.8° F.
Water for mining has been supplied in the Angels Camp district by Utica Mining Company. The same company, and Pacific Gas and Electric Company, supply electric power to the mines, the latter com- pany having a hydroelectric plant near the north county-line.
The lode is below the line where good timber grows, and nearby stands on the foothills have been cut ; but there is plenty of good pine (largely yellow pine) in the higher hills within a short truck-haul to the east.
Transportation.
Sierra Railway of California serves the Carson Hill and Angels Camp districts with a branch line from Tuolumne County. The north- ern end of the lode is served by a branch of the Southern Pacific Rail- road to Valley Spring.
Analysis of Gold Production, Calaveras County, 1914-1933, Inclusive
County's total gold*
Mother Lode mines
Year
Tons ore
Average per ton
Gold per
ton of
concentrates
Mother Lode gold
19)4
$1,336,875
1,391,134
1,356,120
1,471,442
871,263
1,550,574
1,439,745
1,495,758
1,413,465
1,205,784
853,961
652,433
576,889
219,217
162,372
103,843
112,913
152,771
186,378
358.231
358,436 369,569 402,278 393,883 306,510 152,862 126,800 182,015 183,733 172,237 142,078 107,542 92,798
792
1,516
Pockets
576 Pockets Pockets '36,000
$2 22 2 28 2 13 2 04 2 08
8 14
9 13 5 92 5 76 5 76 5 OS
4 96
5 07 17 69
9 87
$23 99 37 92 36 10 13 44 20 20 45 08 57 51 56 77 54 91 52 43 68 22 65 62 77 45 93 36
$797,267
1915
844,610
1916
857,583
1917
805,323
1918 --- ---
638,626
1919
1,244,130
1920
1,157,983
1921... .
1,078,698
1922 --
1,058,920
1923
992,625
1924 ---
722,847
1925
533,803
1926—
470,844
1927
14,017
1928
14,976
1929
5,388
1930
6 63
3,820
1931
5,472
1932
1933
■1 80
'65,000
* All gold values in this report are figured on a value of $20.67 a Troy ounce. ' Estimated, 1933.
MOTHER LODE GOLD BELT
127
Angels Mine at Angels Camp is an interesting example of a small Mother Lode mine which was operated at low cost on varying grades of ore over a lengthy period, because of careful management.
The claim from which the later consolidation took its name was first worked in the late 1850 's and before 1870 had been worked to a depth of 186 feet and for a length of 350 ft. The ore in 1867 was said to yield only $8 a ton though assaying $15 to $20.
Gold and Silver Production of Calaveras County, 1880-1933
Year
Gold, value
Silver, value
Year
Gold, value
Silver, value
1880
1320,865
800,000
670,000
500,000
485,000
527,538
639,457
640,417
580,000
592,243
618,821
738,883
794,531
1,669,192
2,119,365
1,717,916
1,546,398
1,439,861
1,019,023
1,265,564
1,649,126
2,024,685
2,072,939
1,904,125
1,789,184
1,836,816
1,644,234
1,097,974
1643 1,200
1908
1909
$1,378,511
1,440,511
1.147,705
1,112,315
962,145
1,175,208
1,336,875
1,391,134
1,356,120
1,471,442
871,263
1,550,574
1,439,745
1,495,758
1,413,465
1,205,784
853,961
652,433
576,889
219,217
162,372
103,843
112,913
152,771
186,378
442,980
$62,727
1881
71,418
1882
1910.
82,866
1883
1911
1912
67,032
1884.
70,748
1885
1886.
2,558
4,926
1,477
1,500
1,071
2,499
4,860
24,441
122
5,183
77
500
1,745
3,462
9,813
80,762
44,687
46,234
68,280
65,611
78,859
74,099
54,420
1913
1914
1915
1916
1917... ...
61,076 60,442
1887
53,298
1888
83,643
1889 .
87,984
1890
1918
84,150
1891
1892
1919
1920
1921
35,876 16,701
1893
10,232
1894
1922
1923 --
11,648
1895
7,316
1895
1897-
1924 -
1925..-,
1926..
7,463 8,324
1898 -.
6,229
1899
1927
1928
1929---
3,982
1900
1,469
1901
3,444
1902
1930 -
1,555
1903.-
1931
989
1904
1932
763
1905
1933
1,937
1906..
1907
Total values
$56,916,469
$1,482,341
The Doctor Hill claim had also been worked seven years between 1857 and 1867. Although it was said it had yielded $250,000 this was less than had been spent on it. Both these mines were working a vein 15 ft. wide in the schist. By 1884 the Doctor Hill had been opened to a depth of 150 ft. where the vein was reported 13 ft. wide, of which 3 ft. was said to be verv^ rich and the balance worth $10 to $12 a ton.
Billings, Crystal, Oneida, Doctor Hill, McCormick, Beda Blood, and Angels claims were grouped by Angels Quartz Mining Company in 1886 and this company operated continuously until March 1, 1918 since which date no work has been done. The total production of the prop- erty is not known. From 1900 to 1918 inclusive the output was about $2,000,000 from ore averaging from $2 to $10 a ton.
The later work was through the Angels shaft 850 ft. deep, from the lowest level of which a winze was sunk 200 ft. and the vein developed on the 1050-ft. level. The ore found on that level was con- sidered to be too far from the shaft to be worked at a profit. A cross- cut was run east 800 ft. from the 850-ft. level and a rich, narrow vein was mined for a length of 400 ft. It was followed both up and down until it pinched to a seam. Although the ore from this vein did much to 'sweeten' the mill-heads, the bulk of tonnage came from the stringer leads in the amphibolite schist. Two of these, called Mother Lode and East veins, were worked. The former was worked in places
128 CALAVERAS COUNTY
20 ft. wide by shrinkage sloping. The footwall was hard diorite and hanging wall heavy, talcose schist. During the last operations ore was taken from the 200-, 400-, and 500-ft. levels. Stopes were from less than 100 to 200 ft. long. Crystal shaft, 600 ft. deep, on the west vein had been sunk 600 ft. but in the later years was used principally as a second entry.
The so-called talc or 'bull quartz' barren zone was cut in the Angels shaft at a depth of about 400 ft. It dipped east 45° and was cut again in the east crosscut on the 850-ft. level 400 ft. from the shaft.
The ore from this mine was crushed in a mill of forty 850-lb. stamps and Frue vanners were used for concentration. An extraction of 90 per cent was claimed.' Concentrate formed 1^ to 2 per cent of ore and yielded $38 to $70 a ton. The mill handled about 200 tons a day.
This company claimed an operating cost of $2.25 a ton in 1913.
Big Spring (Graham) Claim covers 1200 ft. in length on the Bull Quartz vein IJ miles south of Angels Camp, This vein strikes about N. 20° W. and outcrops continuously throughout the length of the claim. The work has been superficial, in search of pockets, and the greatest depth reached was only 75 to 100 ft. in a shaft long since caved,
Demarest, McCauley, Pioneer, Martinusen, Johnson, Hale and Smyth claims, composing the old Brovm-Smyth-Ryland Consolidated and adjacent ground, was last prospected in 1920-1921 by Angels Camp Deep Mining Company. The claims adjoin the Lindsay claim of Utica Mining Company on the east and northwest. The early-day production of these claims, from shallow workings, is unknown. From 1889 they made some small and irregular output. The Pioneer shaft was 187 ft. deep with 487 ft. of crosscuts and Smyth shaft was 140 ft. deep, with two levels and 692 ft. of crosscuts, before the last company started work. They deepened Pioneer shaft to 500 ft. on an angle of 83° with levels at 300, 400, and 500 ft.
The stringer lead formation was from 5 ft. to 32 ft. wide in different workings. About 1600 ft. of new drifts and crosscuts were run, but the small tonnages of material milled were not on the average of payable grade.
A 20-stamp mill which had been put on the claims in 1921 was sold in 1929 and removed to the Osborne property.
Bruner, St. Lawrence or Bald Hill Mine, two miles south of Angels Camp, comprises eight claims. Apex, Evening Star, De Wet, Spring Gulch, Cold Hill, Eomaggi & Costa, Bald Hill and New Discovery. In 1897, the Bald Hill was worked in a small way by F. Bruner, who hauled ore to the TuUoch mill. Previously, this claim had been pros- pected to a depth of 300 ft. (incline) but there is no record of the results. In 1899, it was taken over by others and named the St, Lawrence. By 1900, ihe shaft had reached a depth of 400 ft. on an incline of 64° with levels at 100 ft. and 400 ft. in depth. There are no records of the results obtained. More work was done in 1913-1914 when mining equipment was installed but no ore was crushed.
The property was worked for placer and gold pockets in early days.
MOTHER LODE GOLD BELT 129
Carson Hill Mines, now being operated by Carson Hill Gold Min- ing Corporation, include Melones, Morgan and Calaveras mines all with separate former histories, extending from the Stanislaus River at Melones to the Bright Star claim of the Chaparral Hill group, including the Morgan, Union, Kentucky, Iron Rock, Relief, Reserve, Enterprise, Irvine, McMillan, Santa Cruz, Calaveras and other claims, covering about a mile and a half on the strike of the lode.
History and Production.
Morgan Mine was discovered in 1850 by Hance who took in six partners, one named Morgan. The claim lies on the northwest side of Carson Hill and was only 550 ft. long, but was so rich that it attracted thousands to the camp. The largest single piece of quartz gold (va^ue $43,534)^ ever reported is claimed to have come from this mine. It is said to have been about five inches in diameter and four to five feet long, and was part of a $300,000 pocket. The ore that was not rich enough to be worked in hand mortars was crushed in arrastres run by Mexicans, who were the only miners there who had had any previous experience in such work. In 1868 - it was stated that the mine was locally credited with a known yield of $2,800,000 between February, 1850, and December, 1851, besides which large sums were supposed to have been stolen by Mexican 'high-graders.' In 1852 a band of several hundred outlaws seized the mine, drove off the owners, and worked it nine months until stopped by injunction. Thereafter, not much mining was done until 1867. This report stated the claim contained two veins which united 100 ft. below the surface. They were the stratified vein (ribbon rock) 6 ft. wide, and the boulder vein ('bull-quartz' vein) 40 ft. wide. The mine in 1867 had been opened only to a depth of 100 ft. where the