By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
The mining districts of Clark County are scattered through the many north-trending mountain ranges characteristic of this part of the State.
Although there is some indication of early small-scale mining by Indians and Spanish explorers, it was not until 1855, when the Mormon settlers began operating the Potosi mine in the Goodsprings district, that large-scale lode mining began. The Potosi is the oldest lode mine in the State (Vanderburg, 1937a, p. 9). Gold-silver deposits were discovered in the Eldorado district in 1857, and some time later, in the Goodsprings and Searchlight districts. These three districts produced most of the metals in the county.
Total recorded county production from 1908 through 1959 was 291,770 ounces. Of this total only 200 ounces was from placers; the remainder was from lode mines or a byproduct of silver, copper, and base-metal ores.
The Eldorado district is 6 miles wide and 12 miles long in the northern Opal Mountains in southeastern Clark County, about 25 miles south of Boulder City.
Mining began in this district in 1857, but it never received the publicity given many other areas, possibly because it was overshadowed by concurrent greater booms at the Comstock Lode, Eureka, and Ely (Ransome, 1907, p. 64). The major mines of the district were the Techatticup, Eldorado Rand, Crown Queen, Wall Street, Mocking Bird, Rambler, Rover, and Flagstaff.
The early production of the Eldorado district was estimated (Ransome, 1907, p. 65) at between $2 and $5 million, mostly in gold. From 1907 through 1959 the production was 101,729 ounces of lode and byproduct gold and 168 ounces of placer gold.
Gneiss and schist, possibly Precambrian in age, have been intruded by a mass of quartz monzonite and are flanked locally by patches of Tertiary volcanic rocks (Ransome, 1907, p. 65-68). Ores occur in fissures in the gneiss and schist and in the quartz monzonite. Most of the veins are small, but very persistent. The minerals present are pyrite, galena, and sphalerite in a gangue of quartz and some cal-cite. The gold and silver probably are associated with the sulfides; native gold has not been seen (Ransome, 1907, p. 76-79).
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