By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Churchill County, in the northern Great Basin, is characterized by many elongate, narrow mountain ranges separated by flat, relatively narrow valleys. Dry or seasonal lakes, the larger of which are in Humboldt and Carson sinks, occupy some of these valleys.
Churchill County, created in 1861, was one of the nine original counties in the State. In later years, parts of the county were used to form Lander, Lyon, and Nye Counties.
Settlers, drawn west by the lure of California gold, crossed Nevada by two main routes, both of which passed through Churchill County. The hot, dry areas occupied by Humboldt and Carson sinks were not inviting; consequently, few people lingered, and the mineral deposits of the county remained undiscovered for some time.
In the early 1860's discoveries were made at Silver Hill, Mountain Well, and Clan Alpine (Browne and Taylor, 1867, p. 128), but it is doubtful that any significant production was achieved.
The discovery at Tonopah, in Nye and Esmeralda Counties in 1900, generated considerable activity, and prospectors overflowed into Churchill County. Discoveries were made at Fairview and Wonder in the early 1900's, and these soon became the most productive gold- and silver-producing areas in the county.
Records of production before 1904 are incomplete, but the value of gold mined from 1890 to 1903 was estimated at $32,300 (about 1,600 ounces). From 1904 to 1937, a total of 12 ounces of placer gold and 123,537 ounces of lode gold was mined in the county (Vanderburg, 1940, p. 10-13). Total gold production through 1959 was 164,605 ounces.
The Fairview district is in southeast Churchill County, 42 miles southeast of Fallon on the west slope of Fairview Peak.
The district was founded in 1906 and became a boom camp immediately. Activity leveled off after a few years, and the Nevada Hills mine emerged as the sustaining producing property until 1917, when it closed. After that time only sporadic small-scale activity was carried on in the district (Vanderburg, 1940, p. 23, 24). Production from 1906 through 1959 was about 53,100 ounces of gold, which was a byproduct from ores that were rich in silver and contained small amounts of lead and copper.
The rocks of the district consist of pre-Tertiary crystalline schists and limestones, intruded by granite (Greenan, 1914). Overlying these older rocks are dacite tuff, two andesite flows, tuff, and rhyolite, all of Tertiary age. A light-gray rhyolite plug cuts all these formations.
Veins occur in fissures in the earlier of the two andesites. The more prominent veins, the Nevada Hill, the Eagle, and the Dromedary, strike northwest and dip steeply southeast. Ore minerals are argentite, stephanite, horn silver, ruby silver, chalcopyrite, pyrite, tetrahedrite, galena, sphalerite, and gold. Gangue consists of quartz, calcite, and minor rhodochrosite and pyrolusite.
SAND SPRINGS DISTRICT
Although the Sand Springs district, which is 25 to 30 miles southeast of Fallon, was prospected in 1905, its first gold production was not until 1919. To 1937 only $30,000 (about 1,450 ounces) in gold was produced, all of it from the Dan Tucker mine (Vanderburg, 1940, p. 40). From 1937 to 1951 the district yielded 20,875 ounces of gold as a byproduct of silver ores. From 1951 through 1959 no activity was reported.
The ore bodies occur in an east-trending silicified zone that cuts country rock consisting of schist, limestone, and andesite. Free gold and minor silver chloride occur in a gangue of sugary quartz and crushed andesite (Vanderburg, 1940, p. 41).
The Wonder district is on the west slope of the Clan Alpine Range in east Churchill County, 55 miles east of Fallon.
The initial gold discoveries were made in 1906, and a rush began immediately (Vanderburg, 1940, p. 54-57). The Nevada Wonder mine soon became the leading producer, a position it never relinquished. The boom was short lived, and after 1919 operations declined to small-scale activities by lessees.
From 1907 through 1959 the district produced 73,890 ounces of gold which was derived from ores rich in silver. The gold-to-silver ratio was 1 to 94. Minor amounts of copper and lead were also produced.
The following description of the geology is summarized from Burgess (1917). The area is underlain by Tertiary rhyolite, dacite, andesite, and basalt. The oldest of these, the Wonder Rhyolite, contains the ore-bearing veins, grouped near small intrusives in the rhyolite. There are many small veins in the district, but only the Nevada Wonder has been productive. The vein is partly on the contact between the Wonder Rhyolite and an intrusive body of dacite.
Silver occurs in the form of argentite and the halogen salts embolite, iodobromite, and iodyrite. The gold is partly included in argentite and is partly free.