Eureka County Nevada Gold Production
The Eureka district is located at the town of Eureka, in southeastern Eureka County.
The first locations were made in 1864, but little was produced until 1869, when large ore bodies were found on Ruby Hill (Hague, 1892, p. 6). The period of greatest production was 1871-88. Hague (1892, p. 6-7) estimated that $20 million in gold was produced from 1869 to 1883. During this period two mines emerged as the major producers—the Eureka Consolidated and the Richmond. After 1888 the major ore bodies were exhausted, the smelters were shut down, and the district entered a period of inactivity broken only by sporadic small-scale mining by lessees. In 1905 the Richmond and Eureka properties were consolidated, and, after the old workings were rehabilitated, shipments of low-grade ore were made. But the low-grade ores could not be profitably mined under constantly increasing costs, and the workings were again closed except for small-scale leasing operations. Several unsuccessful exploratory ventures took place in 1919 and 1923. In 1937, however, the Eureka Corp., Ltd., discovered a new ore body. The Fad shaft was sunk to exploit this ore, but in 1949 work was halted at a depth of 2,500 feet because of the large flows of water that were encountered. Other more recent exploration in the Adams Hill area was more successful; considerable ore was mined from the T. L. shaft. There has also been a renewal of activity in the Diamond mine, about 4 miles south of Eureka (Nolan, 1962, p. 2-3).
The production of the Eureka district is difficult to ascertain, but annual production has been tabulated by Nolan (1962, p. 56-59) from what he considered to be reliable sources.
Using Hague's (1892, p. 6-7) estimate of $20 million (967,585 ounces) in gold from 1869 to 1883 and Nolan's (1962, p. 58-59) data from 1884 through 1959, we arrive at an approximate total gold production of 1,230,748 ounces, which, in view of the generalized nature of Hague's estimate, should be rounded off to 1,230,000 ounces.
The rocks of the Eureka district consist of a thick section of Paleozoic sedimentary rocks, a Cretaceous sedimentary formation, and Cretaceous and Cenozoic igneous rocks.
The Cambrian formations, which in total are about 9,000 feet thick, are, in ascending order, the Prospect Mountain Quartzite, Pioche Shale, Eldorado Dolomite, Geddes Limestone, Secret Canyon Shale, Hamburg Dolomite, Dunderberg Shale, and the Windfall Formation (Nolan, 1962, p. 5-9). Rocks of Ordovician age are about 2,200 feet thick and consist of the Pogonip Group, Eureka Quartzite, and Hanson Creek Formation. The Devils Gate Formation of Devonian age, the Chainman Shale and Diamond Peak Formation of Mississippian age, and the Carbon Ridge Formation of Permian age complete the Paleozoic sequence. Scattered outcrops of the Newark Canyon Formation of Early Cretaceous age unconformably overlie the older rocks (Nolan, 1962, p. 9-13). Igneous rocks of Cretaceous age consist of a plug of quartz diorite and a sill-like mass of quartz porphyry. Other igneous rocks range in age from Oligocene to late Tertiary or Quaternary and include hornblende andesite, rhyolite, rhyolite tuff, andesite, and basalt (Nolan, 1962, p. 13-17).