By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
In 1910 this county was created from what was formerly the north part of Esmeralda County. Typical of the Great Basin, Mineral County contains narrow, elongate mountain ranges separated by valleys having interior drainage. Most of the mountain ranges are mineralized; the principal ranges are the Wassuk, Gabbs Valley, Gillis, Pilot, and Excelsior. A great variety of mineral products has been mined in this county; gold has been the most valuable product, but considerable amounts of silver, lead, zinc, copper, tungsten, and mercury have been mined.
Production data for the county go back only to 1910, when the county was founded. Vanderburg (1937b, p. 10) listed 219,435 ounces of lode gold and 1,963 ounces of placer gold for 1910-34. From 1935 through 1959 production was 43,986 ounces of lode gold and 738 ounces of placer gold. Total gold production for Mineral County from 1910 through 1959 was 266,122 ounces.
The Aurora district is in western Mineral County, 3 miles east of the Nevada-California State line and 30 miles southwest of Hawthorne.
Gold-silver veins were discovered here in 1860. Almost immediately a town named Esmeralda was built, but less than a year later it was abandoned in favor of a site XXX miles north that is the present location of the town of Aurora, which by 1864 had a population of about 10,000 (Hill, 1915, p. 141). Despite litigation over claims and uncertainty about the location of the California-Nevada boundary, the district prospered until the mid-1880's when the high-grade ore was depleted. In the 1930's there was only small-scale mining by lessees, and the town of Aurora, though substantially built, was almost in ruins (Vanderburg, 1937b, p. 14).
Data for production in the early days are incomplete. Hill (1915, p. 142) estimated at least $27 million in gold and silver from 1861 to 1869. For the same period, Vanderburg (1937b, p. 14, 15) estimated at least $30 million in precious metals. From 1910 to 1920 the district produced $1,882,861 (about 91,400 ounces) in gold; the total through 1959 was about 93,600 ounces.
The following account of the geology is condensed from Hill (1915, p. 143-150). Nearly all the rocks exposed in the area are of volcanic origin and consist, from oldest to youngest, of biotite-quartz latite, andesite, rhyolite, and basalt. After each of the periods of extrusion of andesite, rhyolite, and basalt were periods of erosion. The oldest flow was extruded on a granitic basement rock.
The ore deposits are in veins that cut the biotite-quartz latite and andesite. Most of the veins strike about N. 45° E. and dip moderately southeast. Most of the veins are 2 to 4 feet thick, but some are as much as 80 feet thick. The veins send off numerous branches which become, in many places, an interlacing network of veinlets. Fine-grained quartz that is usually banded makes up the bulk of the veins; small cavities lined with tiny quartz crystals are common.
The ore consists of quartz, adularia, argentiferous tetrahedrite, pyrite, chalcopyrite, and a soft blue-gray material containing gold and possibly silver with selenium. Free gold is present in the richest ores. The occurrence of selenium without tellurium in these ores is unusual and has been noted in only a few mining camps.
The Bell (Cedar Mountain) district is in the Cedar Mountain Range in eastern Mineral County near the Nye County border.
The silver-lead deposit at the Simon mine was discovered in 1879, but the gold deposits in this area were not found until later. Gold was discovered at the Copper Contact mine in 1902 and at the Olympic (or Omco) mine in 1915 (Vanderburg, 1937b, p.19).
Before 1919 the Olympic mine yielded $700,000 (about 32,000 ounces of gold) in ore that contained gold with a fineness of 500 (Knopf, 1921a, p. 381). Total gold production of the district through 1959 was about 34,000 ounces.
The gold deposits are associated with Tertiary volcanic rocks - rhyolites and andesites - that underlie lake beds of the Esmeralda Formation (Knopf, 1921a, p. 377-380). At the Olympic mine, the vein is in the upper of two rhyolite flows that have a trachyte flow between them. The vein consists of white sugary quartz containing gold that is not readily visible and is faulted in several places. At the Golden Mile and Clay Peters mines, gold-bearing quartz veins occur in the Luning Formation of Triassic age (Ross, 1961, table 6.1).
Silver veins were discovered in the Candelaria district, which is 22 miles south of Mina in the Candelaria Mountains, in 1863 by a party of Spaniards. The town of Columbus was founded, but the district developed slowly because of the complex mineralogy of the oxidized ores. In the 1870's, the Northern Belle mine was successfully developed. The town of Candelaria was soon constructed near the mine, rail connections were made, and the district became one of the leading silver camps in the State.
In 1884 the Northern Belle mine was involved in litigation and was sold. About this time the Mount Diablo mine became an important producer, and this mine and the Argentum (the consolidated Holmes and Northern Belle) kept the district booming until the bonanza ores were exhausted in the early 1890's (Knopf, 1923, p. 4-5). The camp declined until 1919, when a brief revival took place under the sponsorship of the Candelaria Mines Co. (Vanderburg, 1937b, p. 25). No important activity has been recorded since, although small-scale operations were reported as recently as 1955 (Page, 1959, p. 9).
The Candelaria has been a silver-producing district, and only relatively insignificant quantities of gold have been recovered. The early production data gave no figures on gold. Knopf (1923, p. 5) mentioned a minimum of $20 million worth of silver to about 1920. From 1903 through 1958, a total of 13,024 ounces of gold was produced.
The oldest rock unit of the district is the Palmetto Formation, composed of chert, dolomite, and shale of Ordovician age (Page, 1959, p. 15-44). This is unconformably overlain by sandstone of the Diablo Formation of Permian age. Overlying the Diablo is the Candelaria Formation, which is composed of sandstone, shale, and a few limestone beds and is of Early Triassic age. A large west-trending mass of serpentine containing fragments of Candelaria shale is exposed in the east-central part of the district.
Numerous basic dikes, older than the serpentine and acidic dikes and younger than the serpentine, occur throughout the district. In the vicinity of the Northern Belle mine a rock is exposed which is a complex of sheared and brecciated metasedimentary rocks and metadolerite. All the foregoing rocks are unconformably overlain by Tertiary and Quaternary volcanic rocks, consisting of basalt, dacitic tuffs and flows, rhyolite, and andesitic breccia.
The pre-Tertiary rocks were complexly folded and faulted, perhaps during several episodes, before deposition of the Candelaria Formation. Folding on an east-west axis occurred during post-Triassic, pre-Tertiary time and was accompanied by shearing, faulting, intrusion of peridotite and dikes, and finally by deposition of metalliferous lodes. Additional faulting began in early Pleistocene time and culminated in the fault blocks which characterize the present physiography.
Several types of veins are found in the Candelaria district, but only one type is of economic importance - mineralized fault zones recognizable on the surface by limonite-stained outcrops of fault breccia. Primary ore consists mainly of pyrite and sphalerite and minor galena, chalcopyrite, and arsenopyrite in a gangue of altered country rock, quartz, and dolomite. Oxidized ore, most of which was mined in the early days, is composed predominantly of limonite and manganese oxide with small amounts of bindheimite, anglesite, smithsonite, and cerussite (Page, 1959, p. 47-58).
The Garfield district is 10 miles northwest of Mina and 25 miles southeast of Hawthorne, just north of a line connecting Hawthorne and Mina.
Silver-gold ore was discovered here in 1882, and in the early days several millions of dollars worth of ore was produced from the principal mine, the Garfield. In later years, the Mabel mine has been an important producer.
Early production of the district is estimated at several million dollars in combined metals (Vanderburg, 1937b, p. 33). Production of gold from 1903 through 1957 was 4,933 ounces. Total gold production of the district through 1959 was probably between 10,000 and 50,000 ounces.
The ore deposits are in quartz veins (?) in volcanic rocks of the Excelsior Formation of Triassic and possible Permian ages and limestone of the Luning Formation of Triassic age (Ross, 1961, p. 82).
GOLD RANGE DISTRICT
The Gold Range (Silver Star, Camp Douglas) district is in the Excelsior Mountains in southern Mineral County, about 7 miles northeast of Mina.
In 1893 veins containing gold and silver were discovered and about $500,000 was produced in the first 10 years (Vanderburg, 1937b, p. 71). Small-scale production continued to 1934, when the increased price of gold caused a noticeable spurt in activity. In 1910 tungsten was discovered in the district.
Total gold production for the district through 1959 was about 97,000 ounces. No activity was reported from the district from 1948 through 1959.
The deposits of the Gold Range district are in veins that branch out from two major faults with a horst between them (Ferguson and others, 1954). Veins on the north fault produced only gold and a little scheelite; veins of the south fault, the Silver Dyke system, were rich in silver and carried only small amounts of gold, and scheelite was encountered at depth. The veins are probably of Pliocene age. Most of the veins are in the Excelsior Formation (Triassic) and the Dunlap Formation (Jurassic) ; a few cut some Tertiary rhyolite, The major constituents of the auriferous veins are free gold and pyrite with comb quartz and some adularia.
The Hawthorne district, near the town of Hawthorne at the south end of Walker Lake, is predominantly a silver district, but it has produced considerable gold as a byproduct.
Mining began at least as early as the 1880's at the Pamlico and LaPanta mines, which are 10 miles east-southeast of the town of Hawthorne but are included in the Hawthorne district. Hill (1915, p. 157) reported an estimated $200,000 worth of production from the LaPanta and about $500,000 from the Pamlico. The amount of gold represented in his production was not given. Vanderburg (1937b, p. 38) reported $300,000 production, mostly in gold, from the LaPanta. In 1906 the Lucky Boy mine was discovered and became the chief producer for a few years, but production from the entire district decreased in recent years.
Vanderburg (1937b, p. 36) listed yearly production from 1904 through 1935â€”a total of 155 ounces of placer gold and 4,700 ounces of byproduct gold was produced. From 1936 through 1959, a total of 5,067 ounces of gold was mined in the district.
Hill (1915, p. 151-155) described the geology in the vicinity of the Lucky Boy mine. Cherty limestones, shales, and sandstones of probable Mesozoic age were faulted and intruded by a granodiorite mass which was later cut by aplitic and basic dikes. Near the intrusion the limestones were metamorphosed, producing a skarn of garnet, tremolite, diopside, quartz, and calcite. The vein at the Lucky Boy is in a fracture that cuts the limestone and granodiorite.
The average width of the vein is 2 to 3.5 feet. Ore consists of fine-grained galena and tetrahedrite and a little pyrite. High-grade ore carries 2,000 to 3,000 ounces of silver per ton, and medium-grade ore carries 50 to 400 ounces of silver to the ton.
MOUNT MONTGOMERY AND ONEOTA DISTRICTS
The Mount Montgomery and Oneota districts are combined here because they adjoin and are geologically similar. They are at the north end of the White Mountain Range, about 4 miles east of Queen, in the southern tip of Mineral County.
The Oneota district was organized in 1862, but no mining was attempted until after 1870 (Vanderburg, 1937b, p. 49). The Indian Queen and the Poorman mines were its major producers. In the Mount Montgomery district, gold, silver, mercury, and fluorspar have been mined. The chief gold mines are the Tip Top and Golden Gate (Vanderburg, 1937b, p. 47, 48).
About $150,000 in gold and silver was produced from the Mount Montgomery district, and about $1 million in gold and silver was produced from the Oneota district up to 1935 (Vanderburg, 1937b, p. 47-49). The amount of gold represented in these totals is not known, but at least 10,000 ounces is assumed. Production of gold from 1935 through 1959 was only 161 ounces; therefore, this combined district is not included in table 10.
Country rock consists of Cretaceous (?) granitic rocks intruded into schists of possible Precambrian age. In the northern part of the district these rocks are overlain by Tertiary felsic volcanic rocks, younger than the Esmeralda Formation. Quartz veins containing gold and silver occur in the volcanic rocks (Ross, 1961, p. 65, 80, pi. 2).
The Rawhide (Regent) district, at the south end of the Sand Springs Range in northeastern Mineral County, is 29 miles east of Schurz and 50 miles southeast of Fallon.
The summary of this district is abstracted from Vanderburg's reports (1936a, p. 120-121; 1937b, p. 58-64).
The initial discoveries were made in 1906. Less than 2 years later the town of Rawhide had been built and was populated by about 4,000 people, but in September 1908 a large part of the town was detroyed by fire. This is predominantly a gold camp, and most production has come from numerous small mines rather than a few large ones. From 1908 through 1935, a total of 1,818 ounces of placer gold and 49,034 ounces of lode gold was produced. Total production from 1908 through 1959 was 2,065 ounces of placer and 50,707 ounces of lode gold.
Although most of the gold came from the lode mines, there was considerable working of placer deposits. The most productive placers were in an area V2 mile wide and 1 mile long on the southeast slope of Hooligan Hill. Vanderburg (1936a, p. 120) reported $250,000 total placer production. This conflicts sharply with the $39,953 total compiled by C. W. Merrill (in Vanderburg, 1937b, p. 60).
The lode deposits are in a network of veinlets that cut the country rocks - rhyolite, dacite, and andesite. Kaolinized rhyolite seems to be most strongly mineralized. Ore minerals are electrum, argentite, and cerargyrite.