Black Rock Mine (Black Rock Tungsten deposit), Black Rock Canyon, Banner Ridge, Chidago District, Benton Range, Mono Co., California, USA
|Latitude & Longitude (WGS84):||37° 40' 60'' North , 118° 31' 0'' West|
|Latitude & Longitude (decimal):||37.68333,-118.51667|
A former W-Cu-Mo mine located in secs. 14 & 23, T3S, R31E, MDM, in Black Rock Canyon, 5.5 km (3.4 miles) ESE of Banner Ridge (coordinates of record) and about 7½ miles S of Benton, on National Forest land. Discovered in 1917 by A.E. Beauregard. First produced in 1928. Owned by the Union Carbide Nuclear Corp. Operated by Wah Chang Mining Corp. MRDS database stated accuracy for this location is 10 meters.
Mineralization is Late Cretaceous in age and hosted in marble and hornfels. Scheelite-bearing tactite occurs over an extensive area in the crest and gently-dipping West limb of an anticlinal sequence of calcareous rocks overlain by sericite hornfels. The ores of this mine also carry some Mo. The ore body is irregular in shape, strikes N and dips W with a depth-to-bottom of 182.88 meters, a width of 365.76 meters and a length of 731.52 meters. Controls for ore emplacement included an asymmetrical anticline that plunges N; contact with pluton. Local alteration involved the formation of tactite and bleaching. Rhyolite is an associated rock. Local rocks include Paleozoic marine rocks, undivided, unit 3 (Eastern Sierra Nevada) and/or Plio-Pleistocene and Pliocene loosely consolidated deposits.
Tectonic structures include the Sierra Nevada Batholith.
Workings include surface and underground openings comprised of 5 open pits and more than a mile of level workings, raises, winzes, and stopes. several open cuts, the largest of which was planned to be 450 feet by 300 feet.
Production information: 272,591 tons total production from 1928 to 1954 averaged a grade of approximately 0.5% WO3.
Reserve resource information: There are large, unexplored areas. Exploration through facility of DMEA 1951-1954 discovered substantial tonnage of ore.
Must use high-cost underground mining methods. Low grade deposit.
14 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
|Pleistocene - Miocene|
0.0117 - 23.03 Ma
|Plio-Pleistocene and Pliocene loosely consolidated deposits|
Age: Cenozoic (0.0117 - 23.03 Ma)
Stratigraphic Name: Arroyo Seco Gravel; Cache Formation; Carlotta Formation; China Hat Gravel; China Ranch Beds; Coso Formation; Funeral Fanglomerate (part); Furnace Creek Formation; Glen Ellen Formation; Irvington Gravels; Kern River Formation; Laguna Formation; Livermore Gravel; McKittrick Formation; North Merced Gravel; Nova Formation; Packwood Gravels; Paso Robles Formation; Red Bluff Formation; Ricardo Formation; San Benito Gravels; Santa Clara Formation; Saugus Formation; Tehachapi Formation; Tulare Formation; Turlock Lake Formation; Alturas Formation; Anaverde Formation; Canebrake Conglomerate; Chanac Formation; Crowder Formation; Duarte Conglomerate; Esmeralda Formation; Etchegoin Formation; Green Valley Formation; Hathaway Formation; Horned Toad Formation; Hungry Valley Formation; Lockwood Clay; Mecca Formation; Meeke Mine Formation; Mehrten Formation; Morales Formation; Mount Eden Formation; Mulholland Formation; Neroly Formation; Orinda Formation; Oro Loma Formation; Painted Hill Formation; Palm Spring Formation; Panorama Hills Formation; Peace Valley Formation; Petaluma Formation; Potato Sandstone; Purisima Formation; Quatal Formation; Ricardo Formation (part); Ridge Route Formation; Santa Ana Sandstone; San Timoteo Formation; Siesta Formation; Tassajero Formation; Tehama Formation; Tropico Group; Wolfskill Formation
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. 
Sampson, Reid J. (1940), Mineral resources of Mono County: California Mining Bureau. Report 36(2): 147-149.
Lemmon, Dwight Moulton (1941b), Tungsten deposits of the Benton Range, Mono County, California: USGS Bulletin 922-S: 587-591.
Partridge, John F., Jr. (1941), Tungsten resources of California: California Journal of Mines and Geology, California Division of Mines (Report 37): 37(2): 314-315.
U. S. Bureau of Mines (1941), Direxpl.
Dupuy, L.W. (1948) Black Rock tungsten deposit, Mono County, California. US Bureau Mines Report of Investigation 4210, 6 pp.: 4, 8.
Rinehart, Charles Dean & Donald C. Ross (1953), Geological Map, Report, maps.
Rinehart, Charles Dean & Donald C. Ross (1956), Economic geology of the Casa Diablo Mountain quadrangle, California: California Division Mines Special Report: 48, 17 pp.: 11-16, Pl. 1.
California Division of Mines and Geology (1957), Bulletin 176: 659-661.
Johnson, A.C. and Fillip, N.M. (1960) Mining methods and costs, Black Rock tungsten mine, Wah Ching Mining Corp., Mono County, California. U.S. Bureau of Mines Information Circular 7945, 19 pp.: 61 (sic).
Lemmon, Dwight Moulton and Tweto, O.L. (1962) Tungsten in the United States, exclusive of Alaska and Hawaii. USGS Mineral Investigative Resources Map MR-25.
Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 176, 280, 331.
Elliott, J.E. (1971), The Mineralogy and Geochemistry of the Tungsten Deposits of the Black Rock Mine, Mono County, California, Stanford University, unpublished PhD Thesis, 131p.
U.S. Bureau of Mines Open-File Report MLA 83-82 (1982), Table 2: 13.
Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 80, 336, 339, 483.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10008717, 10164583 & 10109270.
U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0060510172.
Lemmon, D.M., Tungsten deposits in the US; Vol. I, unpublished data.
Defense Minerals Exploration Administration (DMEA) Reports Index California-Nevada, DMA No. 1377: 5.