By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Gold has been produced from numerous mines scattered throughout Inyo County, but, unfortunately, details of the geology and production of individual districts are incomplete.
From 1880 through 1959, a total of 496,000 ounces of gold was mined in the county. Most of this was lode production, but a considerable quantity was a byproduct from lead-silver, tungsten, and copper ores.
Mining began as early as 1861 (Knopf, 1918, p. 105) in the Russ district in the Inyo Range, but production data for these early years are incomplete.
The lode deposits are scattered throughout numerous mountain ranges in the county. The most important gold-producing districts are the Ballarat and Wild Rose in the Panamint Range, the Chloride Cliff in the Funeral Range, the Resting Springs in the Nopah Range, the Sherman in the Argus Range, the Union in the Inyo Range, and the Willshire-Bishop Creek, an important tungsten district on the east slope of the Sierras.
In the early days, gold placers were worked on a small scale in Mazourka and Marble Canyons, on the west and east slopes of the Inyo Range.
The Ballarat (South Park) district, at about lat 36°00' N. and long 117°10' W., is in the Panamint Range in south-central Inyo County.
The Ratcliff mine, the chief mine in this district, was located in 1897 and in the next 6 years it produced gold valued between $300,000 and $1 million (Norman and Stewart, 1951, p. 47-48). After an indefinite period of inactivity, the mine produced $250,000 in gold from 1927 to 1942 (Norman and Stewart, 1951, p. 48). A much more conservative estimate of $500,000 as the total production from the entire district was given by Nolan (1936b, p. 39). The district was active on a small scale in 1959.
The Ratcliff ore body is in a north-trending vein in country rock that has been described variously as a biotite schist, sericite schist, metaquartzite, or conglomerate schist (Norman and Stewart, 1951, p. 48). The vein consists of quartz lenses and masses containing gold associated with pyrrhotite, pyrite, and chalcopyrite.
CHLORIDE CLIFF DISTRICT
The Chloride Cliff district, at lat 36°40' N. and long 116°55' W., is on the slope of the Funeral Range.
The district, discovered about 1903, had a total gold production of about 60,000 ounces through 1959, mostly from Keane Wonder mine. Most of the activity in the district occurred before 1916 (Nolan, 1936b, p. 36), and since then there has been only sporadic small production.
Only brief accounts of the geology of the district were found in the literature. Nolan (1936b, p. 36) reported that the deposits consisted of gold-bearing quartz veins in Paleozoic sedimentary rocks. Norman and Stewart (1951, p. 38) stated that lenticular quartz ore bodies are enclosed in schist at the Keane Wonder mine.
RESTING SPRINGS DISTRICT
Gold is a byproduct from lead-silver ores in the Resting Springs district, which is '5 to 10 miles east of Tecopa, in the southeast corner of Inyo County.
Discovered in 1865, the district produced very little before 1910 (Nolan, 1936b, p. 39). The period 1912-28 was one of fairly large scale activity and about $3 million in lead and silver was produced from the Shoshone group of mines (Norman and Stewart, 1951, p. 80). The amount of gold produced in this interval is not given. From 1939 to 1959 the district produced 15,005 ounces of gold.
Only brief accounts of the geology of this district appear in the published literature. Nolan (1936b, p. 39) described the deposits as lenticular bodies of oxidized lead-silver ore along fissures in Paleozoic sedimentary rocks. Norman and Stewart (1951, p. 80) stated that the country rock is Noonday Dolomite, of Early Cambrian age, and that the ore deposits are fissure fillings in a fault zone that strikes northwest and dips moderately to the northeast.
The ore is localized at the intersections of the main fault zone with nearly vertical north-trending cross fractures. The predominant ore minerals are argentiferous galena in the primary ore and cerus-site and anglesite in the oxidized ore.
The Sherman district is 10 to 15 miles southwest of Ballarat, in T. 23 S., Rs. 42 and 43 E., in the Argus Range.
The chief gold producers have been the Arondo and the Ruth gold mines; other mines in the district worked for lead and silver have also yielded gold as a byproduct.
There was some activity in the district from the 1890's through World War I (Norman and Stewart, 1951, p. 38). From 1939 through 1941, the district produced 14,184 ounces of lode gold. No production was reported from 1942 to 1959 and data before 1932 have not been found.
The deposit at the Arondo mine consists of finely divided free gold in quartz fragments and stringers mixed with talcose and clay gangue, and siderite and hematite in a shear zone in granitic country rock (Norman and Stewart, 1951, p. 38, 49). At the Ruth mine, the ore consists of free gold associated with pyrite in iron-stained quartz stringers in a fissure in quartz monzonite country rock.
The Union (Inyo Range) district is between lat 36°35' and 36°45' N. and long 118°00' and 118°10' W., in the Inyo Range in north-central Inyo County.
Gold deposits were discovered in the 1860's by Mexicans (Knopf, 1918, p. 118). Both veins and placers were worked, but the placers were soon exhausted. Many veins in the district have been worked, but the chief producers were the Reward and Brown Monster veins which produced $200,000 in gold before 1884 (Knopf, 1918, p. 121).
In more recent years operations in the district have been desultory. Total gold production for the district could not be determined, but was estimated to be between 10,000 and 50,000 ounces. The geology of the area was described by Knopf (1918, p. 121-122, pi. 2). The country rock consists of Carboniferous shale, limestone, and conglomerate, and Triassic shales, tuffs, and volcanic breccias. These rocks were intruded by masses of granite and quartz monzonite and the veins are distributed near the contacts between the intruded and intrusive rocks.
The near-surface ore is highly oxidized and consists mainly of quartz and minor amounts of limonite, calamine, chrysocolla, and wulfenite. Unoxidized ore consists of quartz with small amounts of pyrite, galena, sphalerite, and chalcopyrite.
WILD ROSE DISTRICT
The Wild Rose district is at about lat 36°25' N. and long 117°07' W., in the Panamint Range.
Deposits were discovered in this area about 1906, and the peak production period was 1908-17, when about $11/2 million, chiefly in gold, was produced from the Skidoo mine (Nolan, 1936b, p. 39). Since then various lessees have worked the property for short periods, but production is not known (Norman and Stewart, 1951, p. 51). Minimum total gold production for this district through 1959 was about 73,000 ounces.
Descriptions of the geology of this area are sketchy. Nolan (1936b, p. 39) reported that the deposits are gold-quartz veins in granitic gneiss. Norman and Stewart (1951, p. 51) stated that there are two systems of veins in a body of quartz monzonite and that both have been explored by more than a mile of underground workings.
WILLSHIRE-BISHOP CREEK DISTRICT
The Willshire-Bishop Creek district, 7 to 17 miles west of Bishop, is on the east slope of the Sierra Nevada and in the Tungsten Hills.
This is predominantly a tungsten district, but some gold has been produced as a byproduct. Activity began about 1916 and continued through 1959. The Pine Creek mine, the largest domestic tungsten producer, was the principal source of gold mined in the district, and through the 1950's was the chief source of gold in Inyo County.
The Cardinal Gold Mining Co. deposit was mined for gold alone, but it has been closed since 1938 (Bateman, 1956, p. 80). The gold production of this district through 1959 was between 75,000 and 100,000 ounces.
In the mineralized parts of the district the predominant country rock consists of a complex of granitic to dioritic intrusive bodies and roof pendants and discontinuous septa of metavolcanic and metasedimentary rocks of varied lithologic types. The metamorphic rocks are of Paleozoic and Mesozoic age; the igneous intrusives are of later Mesozoic age (Bateman, 1956, p. 9).
At the Pine Creek mine, a folded pendant almost 7 miles long that consists of marble, biotite-quartz, hornfels, and metavolcanic rocks is bounded by granite, quartz monzonite, and hornblende gabbro. The tungsten ore bodies are in masses of tactite in the marble along its contact with quartz monzonite.
Scheelite and powellite are disseminated in pyroxene and garnet tactite. Molybdenum ore shoots are in silicified zones in tactite bodies containing the ore minerals molybdenite, chalcopyrite, and bornite. Gold is recovered from these sulfides during smelting (Bateman, 1956, p. 22-34).
The deposit at the Cardinal mine is in a shear zone in quartzite in a quartzite and schist septum bordered by quartz monzonite and granodiorite. The ore minerals, which are finely disseminated in the sheared quartzite, consist dominantly of pyrrhotite with lesser amounts of arsenopyrite, sphalerite, chalcopyrite, pyrite, and molybdenite. Most of the gold is in the sulfides, but some of it is free (Bateman, 1956, p. 80, 81).