Inyo County California Gold Production
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.
SHERMAN DISTRICT
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.
UNION DISTRICT
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.