Majuba Hill Mine (Majuba Mine; Mylar Mine; Tin Mine; Nevada Bureau of Mines and Geology sample sites 2844 & 2846), Antelope District, Pershing Co., Nevada, USA
|Latitude & Longitude (WGS84):||40° 40' 9'' North , 118° 28' 12'' West|
|Latitude & Longitude (decimal):||40.66917,-118.47000|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
A former Cu-As-Au-Pb-Mo-Ag-Sn-U mine located in sec. 2, T32N, R31E, MDM, 0.6 km (0.3 mile) S of Majuba Mountain (coordinates of record), about 50 miles NNW of Lovelock, on private land. Operated by the Greenan-Kerr Tin Co. Owned by the Jumbo Mining Co., Seabrook, Texas. MRDS database stated accuracy for this location is 100 meters.
Mineralization is essentially a Cu-Sn-As deposit (Deposit Model code: 50; USGS model code 16; deposit model name: Climax Mo). The ore body is tabular, strikes N30W and dips 54-84SW, at a thickness of 3.05 meters. Controls for ore emplacement included fault zones.
The Cu ore bodies were formed by the enrichment in Cu of a relatively narrow zone beneath the oxidized zone, localized along the Majuba Fault. Cassiterite occurs widely and unevenly in many rock types in the mine, but is economically concentrated in some rubbly, vuggy breccia (about 20 x 20 x 10 feet), near the Majuba Fault, in the zone of supergene enrichment of Cu. It is suggested (by Smith and Gianella 1942) that the Sn & Cu deposits were formed either during two separate periods of mineralization, or during two distinct phases of a single period of mineralization. The U deposit (metazeunerite) occurs in a 3 foot wide Cu- & Sn-bearing vein in the southern portion of the Cu stope. Trites and Thurston (1958) believe the metazeunerite was derived from the oxidation of a primary U mineral, either uraninite or coffinite, deposited with the primary sulfide minerals and subsequently moved downward to combine with the Cu to form the secondary U mineral in the zone of supergene enrichment. The wallrocks are tourmalinized and cut by chalcopyrite-bearing tourmaline stockwork veinlets. The main Cu stope contains chalcocite-rich pods 1 to 10 inches (2.5 to 25 cm), with centers of pyrite, chalcopyrite and minor enargite, surrounded by digenite and chalcocite. The Nure report on the Lovelock Quadrangle reported an U occurrence on the second level adit on the S face of Majuba Hill, about 600 to 800 feet from the mouth of the second level adit. They also reported a 3-foot wide zone of 0.30% U3O8 in a Cu chute area, which was mined out earlier with the Cu. Two of their samples from the second level adit ran 1-65 and 179 ppm U3O8, respectively (samples MEX 073 & MEX 074.).
Local alteration includes tourmalinization, sericitization and argillization. Local rocks include Pliocene Rhyolitic intrusive rocks and Shale, mudstone, siltstone, sandstone, and carbonate rock; sparse volcanic rock.
Local geologic structures include the Majuba Fault.
Workings include underground openings with a length of 621.79 meters and an overall depth of 106.68 meters, and comprised of 3 tunnels.
The mine was not operating when examined in 1984, although it appeared to be in fair condition. Cassiterite float was discovered in 1907, but Sn was not found underground until 1914.
Production data are found in: MacKenzie and Bookstrom (1976); Johnson, M.G. (1977).
The Majuba Hill Mine was operated by Mason Valley Mines Co., shipped 4,000 tons of 12% Cu ore between 1916-1919. In 1943 the Majuba Mine was reactivated by the Greenan-Kerr Tin Mine Co. which mined 350 tons of ore with 2-4% Sn. Between 1943 and 1945, the mine produced Cu & Sn containing Au, Ag & Pb valued at more than $275,000 (period values). Only a small quantity of Cu has been mined since then.
Reserve-Resource data are found in: Johnson, M.G. (1977).
Only a very small reserves of known Cu & Sn ore remain. Recent exploratory drilling indicates possible additional reserves.
Mineral ListMineral list contains entries from the region specified including sub-localities
102 valid minerals. 2 (TL) - type locality of valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Miocene - Middle Eocene|
5.333 - 47.8 Ma
|Rhyolitic intrusive rocks with aphanitic groundmass|
Age: Cenozoic (5.333 - 47.8 Ma)
Description: Tertiary rhyolitic intrusive rocks also are present in every county of Nevada. They include many rocks mapped as rhyolite or rhyolite porphyry, rhyolite intrusive rocks, rhyolite plugs or flows, microgranite dikes, and many other undifferentiated intrusive rocks.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.