McDermitt Mine [including older Cordero mine complex], Opalite District, Humboldt Co., Nevada, USA
|Latitude & Longitude (WGS84):||41° 55' 9'' North , 117° 48' 44'' West|
|Latitude & Longitude (decimal):||41.91943,-117.81225|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
The Cordero mines and McDermitt mine are located in the Opalite mercury mining district in the United States of America. The Opalite mercury mining district encompasses locations that are both in the state of northern Nevada and in the state of southern Oregon. The deposits are all related to a large volcanic center (caldera complex) called the McDermitt caldera complex. Mines in the Opalite district include those listed below.
Bretz Mine, Malheur Co., OR, USA
Cordero Mine, Humboldt Co., NV
Corderito Mine, Humboldt Co., NV
Crofoot Project, Humboldt Co., NV
Disaster Peak Property, Humboldt Co., NV
Lenway Mine, Humboldt Co., NV
McDermitt Mine, Humboldt Co., NV
Opalite Mine, Malheur Co., OR
Ruja Mine, Humboldt Co., NV
The Cordero mine was the first discovery of mercury in the district, quickly followed by the Bretz and Opalite mines to the north. These were both underground and open cut operations. In the 1970s, mercury was discovered in tuffaceous lake sediments adjacent to and just north of the Cordero mine. This deposit was exploited exclusively by open cut mining. It was named the McDermitt mine, and operated by Placer Amex until acquired by Barrick Gold Corporation. The McDermitt mine was the last operating primary mercury production mine in the USA when it ceased operations in 1990. The patented mining claims of the McDermitt mine were still owned by Barrick Gold as of March 2016, but the mine is closed and there is no mining activity in the district.
The following summary prepared by Michael Cox is drawn from the extensive body of references and more than five weeks of detailed field examination of the pit during the period of late-2014 to early-2017.
The McDermitt open pit mine was excavated in lacustrine and/or fluvial tuff under a thin mantle of recent (Pleistocene) alluvial gravel. According to Giraud (1986) and McCormack (1986) the tuff was only locally reworked by water prior to consolidation. Fragments are nearly always angular, suggesting the source material was unconsolidated pyroclastic debris rather than eroded consolidated rock layers. The parent rock is pyroclastic, with angular fragments of peralkaline rhyolite that contains alkali feldspar phenocrysts, sometimes several centimeters long or larger. During violent gaseous eruptions, the parent magma was fragmented at the vent, blown upward, and deposited on the surface, including into and over lakes and streams. The resulting pyroclastic ash and debris was laid down on the surface of the land existing at the time and later consolidated into rock. The volcanic rocks vary with depth and age, but the main ash deposit is broadly called McDermitt Tuff by Henry et al. (2016), and according to them, the main eruption of tuff occurred at 16.35±0.03 Ma. After the main tuff eruption, the volcanic source chamber collapsed to form an oval surface depression called a caldera. The McDermitt caldera measures 25 miles (40 km) north-south by 14 miles (22 km) to 19 miles (30 km) east-west. Hydrothermal fluids then deposited the antimony and mercury mineralization and silicified the parent tuff. This occurred at about 15.7±0.4 Ma based on Noble et al. (1988) dating adularia from the open pit ore. Sometimes the silica and ore replacement is so thorough the parent rock textures and grains can no longer be recognized, even in thin sections under the microscope.
38 valid minerals. 3 (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
|Pleistocene - Pliocene|
0.0117 - 5.333 Ma
|Older alluvium and alluvial fan deposits|
Age: Cenozoic (0.0117 - 5.333 Ma)
Description: Unit consists mostly of older alluvium and alluvial fans. It also includes various stream deposits, gravel, fanglomerates, and older gravels. It is not very consistent in description from county to county. This is used in all counties except Clark.
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. 
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Bailey, E.H., Hildebrand, F.A., Christ, C.L. and Fayhe, J.J. (1959) Schuetteite, a new supergene mercury mineral. American Mineralogist, 44, 1026-1038.
Brooks, H.C. (1959) Quicksilver in Oregon. Oregon Department of Geology and Mineral Industries. Presented at the geology session of the 1959 Pacific Northwest Regional Conference, AIME.
Curry, D.L. (1960) The geology of the Cordero quicksilver mine area, Humboldt County, Nevada. M.S. thesis, University of Oregon, Eugene, Oregon.
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Carlson, E.H. (1967) The growth of HgS and Hg3S2Cl2 single crystals by a vapor phase method. Journal of Crystal Growth, 1, 271-277.
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Greene, R.C. (1976) Volcanic rocks of the McDermitt caldera, Nevada-Oregon: U.S. Geological Survey Open-File Report 76-753, 80 pp.
McKee, E.H. (1976) Origin of the McDermitt caldera in Nevada and Oregon and related mercury deposits. Trans. AIME 260, 196-199.
Roper, M.W. (1976) Hot springs mercury deposition at McDermitt mine, Humboldt County, Nevada. Trans. AIME 260, 192-195.
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Speer, W.E. (1977) Geology of the McDermitt mine area, Humboldt County, Nevada. M. S. thesis, University of Arizona, Tucson, Arizona, 65 pp., 2 plates.
Rytuba, J.J. and Glanzman, R.K. (1978) Relation of mercury, uranium, and lithium deposits to the McDermitt caldera complex. U.S. Geological Survey Open File Report 78-926, 31 p. Nevada Bureau of Mines and Geology Report 33, 109-117.
Bennet, R.E. (1979, Sept. 6) United States Department of the Interior, Bureau of Land Management, Serial N-20319, Mineral Report, Mineral Patent Application of Placer Amex, Inc. and Sterling Mineral Venture, 24 pp.
Glanzman, R.K. and Rytuba, J.J. (1979) Zeolite-clay mineral zonation of volcaniclastic sediments within the McDermitt caldera complex of Nevada and Oregon. U.S. Geological Survey Open File Report, 79-1668.
Rytuba, J.J., Conrad, W.K. and Glanzman, R.K. (1979) Uranium, thorium, and mercury distribution through the evolution of the McDermitt caldera complex. U. S. Geological Survey Open File Report 79-541.
Rytuba, J.J., Glanzman, R.K. (1979) Relation of mercury, uranium, and lithium deposits to the McDermitt caldera complex, Nevada-Oregon. Nevada Bureau of Mines and Geology, Rept. 33, 109–117.
Wallace, A.B., Drexler, J.W., Grant, N.K., Noble, D.C. (1980) Icelandite and aenigmatite-bearing pantellerite from the McDermitt caldera complex, Nevada-Oregon: Geology, v. 8, 380–384.
Jenkins, R.E. (1981) Minerals of Nevada (Draft # 6). Unpublished manuscript, 280 pp.
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Wallace, A.B. and Roper, M.W. (1981) Geology and uranium deposits along the northeastern margin, McDermitt caldera complex, Oregon: AAPG Studies in Geology No. 13, 73–79.
Castor, S.B., Mitchell, T.P., and Quade, J.G. (1982) National Uranium Resource Evaluation, Vya quadrangle, Nevada, California and Oregon: U.S. Department of Energy Open-File Report PGJ/F135(82).
Hetherington, J.J. (1983) The Geology and Mineralization at the McDermitt Mercury Mine, Nevada. M.S. thesis, University of Washington, Seattle, Washington.
Rytuba, J.J., Bateson, J.T., Curtis, D.L., and Cox, G.A. (1983) Geologic map of the Little Whitehorse Creek quadrangle, Harney and Malheur Counties, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map 1472, scale 1:24,000.
Rytuba, J.J., and McKee, E.H. (1984) Peralkaline ash flow tuffs and calderas of the McDermitt volcanic field, southeastern Oregon and north central Nevada: Journal of Geophysical Research, v. 89, 8616–8628.
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Dayvault, R.D., Castor, S.B. and Berry, M.R. (1985) Uranium associated with volcanic rocks of the McDermitt Caldera, Nevada and Oregon, in Uranium deposits in volcanic rocks: Proceedings of a technical committee meeting: Panel Proceedings Series-International Atomic Energy Agency, STI/PUB/690, 379-409.
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Giraud, R.E. (1986) Stratigraphy of Volcanic Sediments in the McDermitt mine, Humboldt County, Nevada. M.S. thesis, University of Idaho Graduate School, Moscow, Idaho, 87 pp., 11 plates.
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Starkel, W.A. (2014) Mapping, geologic evolution and petrogenesis of the McDermitt volcanic center, northern Nevada and southern Oregon, USA. Ph.D. thesis, Washington State University, School of the Environment, 407p.
Henry, Christopher D., Castor, Steven B., Starkel, William A., Ellis, Ben S., Wolff, John A., McIntosh, William C., and Heizler, Matthew T. (2016) Preliminary geologic map of the McDermitt caldera, Humboldt County, Nevada and Harney and Malheur counties, Oregon, Nevada Bureau of Mines and Geology, Open File Report 16-1, 1 plate, 8 p.
Placer Amex, Inc., McDermitt Mine (Date Ukn.), a corporate brochure, 8 p.