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McDermitt Mine [including older Cordero mine complex], Opalite District, Humboldt Co., Nevada, USA

This page kindly sponsored by Michael Cox
Latitude & Longitude (WGS84): 41° 55' 9'' North , 117° 48' 44'' West
Latitude & Longitude (decimal): 41.91943,-117.81225
Area:2.0 km2
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[1][2][3].

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[4] (1986) and McCormack[5] (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.[6] (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.[7] (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.

Mineral List

38 valid minerals. 3 (TL) - type locality of valid minerals.

Regional Geology

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

Pleistocene - Pliocene
0.0117 - 5.333 Ma

ID: 2777353
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.

Lithology: Major:{coarse alluvium,fine alluvium}

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. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Yates, R.G. (1942) Quicksilver deposits of the Opalite district, Malheur County, Oregon and Humboldt County, Nevada. U. S. Geological Survey Bulletin 931-N, 319-348.

Bailey, E.H. and Phoenix, D.A. (1944) Quicksilver deposits in Nevada. University Nevada Bulletin 38, 206 pp.

Frondel, C. (1956) Mineral composition of gummite. American Mineralogist, 41, 539-568.

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.

Puff, H. and Kohlschmidt, R. (1962) Quecksilberchalkogenid-halogenide. Naturwissenschaften, 49, 299.

Brooks, H.C. (1963) Quicksilver in Oregon. Oregon Department of Geology and Mineral Industries Bulletin B-055. 223 pp.

U.S. Bureau of Mines Staff (1965) Mercury potential of the United States. USBM IC 8252, Part 2 of 2, 224-225.

Carlson, E.H. (1967) The growth of HgS and Hg3S2Cl2 single crystals by a vapor phase method. Journal of Crystal Growth, 1, 271-277.

Fisk, E.L. (1968) Cordero mine, Opalite mining district. In, J. D. Ridge, Ed., Ore Deposits of the United States, 1933-1967, vol. 2, p. 1573-1591. AIME Publ.

Frueh, A.J. and Gray, N. (1968) Confirmation and refinement of the structure of Hg3S2Cl2. Acta Crystallographica, B24,156-157.

Greene, R.C. (1972) Preliminary geologic map of the Jordan Meadow quadrangle, Nevada-Oregon. U.S. Geological Survey Misc. Field Studies Map MF-341.

Foord, E.E., Berendsen, P., and Storey, L.O. (1974) Corderoite, first natural occurrence of α-Hg3S2Cl2, from the Cordero mercury deposit, Humboldt County, Nevada. American Mineralogist, 59, 652-655.

McKee, E.H., Greene, R.C., and Foord, E.E. (1975) Chronology of volcanism, tectonism, and mineralization of the McDermitt caldera, Nevada-Oregon (abs.) Geol. Soc. America, Abs. with Programs, 1, No. 5, 629-630.

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.

Rytuba, J.J. (1976) Geology and ore deposits of the McDermitt caldera, Nevada-Oregon. U. S. Geological Survey Open File Report 76-535.

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.

Roper, M.W. and Wallace, A.B. (1981) Geology of the Aurora uranium prospect, Malheur County, Oregon, in Goodell, P.C., Waters, A.C., editors, Uranium in Volcanic and Volcaniclastic Rocks: AAPG Studies in Geology, v. 13, 81–88.

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.

Farmer, J.R. (1984, December) Review of National Emission Standards for Mercury, U.S. EPA Office of Air Quality, Report number EPA-450/3-84-014, 72 pp.

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.

Hetherington, J.J. and Cheney, E.S. (1985) Origin of the opalite breccia at the McDermitt mercury mine, Nevada. Economic Geology, 80, 1981-1987.

Mining Annual Review (1985) Mining Journal, 120.

Storey, L.O. (1985) History of the discovery of the McDermitt mine, McDermitt, Nevada. Trans. AIME 260.

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.

McCormack, J.K. (1986) Paragenesis and origin of sediment-hosted mercury ore at the McDermitt mine, McDermitt, Nevada. M.S. thesis, University of Nevada, Reno, Nevada.

Minor, S.A. (1986) Stratigraphy and structure of the western Trout Creek Mountains and northern Bilk Creek Mountains, Harney County, Oregon, and Humboldt County, Nevada: M.S. thesis, University of Colorado, Boulder, 177 pp.

Leszcykowski, A.M. (1987) Mineral resources of the Disaster Peak study area, Harney and Malheur Counties, Oregon and Humboldt County, Nevada. U. S. Bureau of Mines Mineral Land Assessment/1987 Open File Report 65-87.

Schlottmann, J.D. Jr., (1987) Last Mercury Mine Closes. California Mining Journal, April, 17-20.

Noble, D.C., McCormack, J.K., McKee, E.H., Silberman, M.L., Wallace, A.B. (1988) Time of mineralization in the evolution of the McDermitt caldera complex, Nevada-Oregon, and the relation of middle Miocene mineralization in the northern Great Basin to coeval regional basaltic magmatic activity: Economic Geology, v. 83, 859–863.

McCormack, J.K., Dickson, F.W. and Leshendok, M.P. (1991) Radtkeite, Hg3S2Cl(I), a new mineral from the McDermitt mercury deposit, Humboldt County, Nevada. American Mineralogist, 76, 1715-1721.

Pierce, K.L., and Morgan, L.A. (1992) The track of the Yellowstone hotspot—Volcanism, faulting, and uplift: Geological Society of American Memoir 179, 1–53.

Rytuba, J.J. and Heropoulos, C. (1992) Mercury; an important byproduct in epithermal gold systems, in DeYoung, J.H., Jr. and Hammarstrom, J.M., eds;, Contributions to commodity geology research. U.S. Geological Survey Bulletin 1877, p. D1-D8.

Jensen, M.C., Rota, J.C., and Foord, E.E. (1995) The Gold Quarry mine, Carlin-trend, Eureka County, Nevada. Mineralogical Record, 26, 449-469.

McCormack, J.K. (1996) Large-scale arcuate structures concentric with the McDermitt Caldera Complex. In Geology and Ore Deposits of the American Cordillera (A.R. Coyner and P. L. Fahey, eds.). Proceedings of the Symposium (Reno-Sparks, Nevada, April 1995). Geological Society of Nevada, Reno, Nevada.

McCormack, J.K. (1997) Mercury sulf-halide minerals and crystalline phases, and experimental formation conditions, in the system Hg3S2Cl2-Hg3S2Br2-Hg3S2I2, Ph.D. thesis, University of Nevada, Reno, Nevada, 154 pp.

McCormack, J.K. and Dickson, F.W. (1998) Kenhsuite, ϒ-Hg3S2Cl2, A new mineral species from the McDermitt Mercury deposit, Humboldt County, Nevada. Canadian Mineralogist, 36, 201-206.

Jambor, J.L. and Roberts, A.C. (1999) New Mineral Names, Kenhsuite. American Mineralogist 84:194

Castor, S.B. and Henry, C.D. (2000) Geology, geochemistry, and origin of volcanic rock-hosted uranium deposits in northwestern Nevada and southeastern Oregon, U.S.A.: Ore Geology Reviews, v. 16, p. 1–40

McCormack, J.K. (2000) The darkening of cinnabar in sunlight. Mineralium Deposita 35(8), 796-798.

Tewalt, N.A. and Carrington, R.G. (2001) U.S. gallium exploration report with report on Cordero property for Gold Canyon Resources (unpublished report, 31 p).

Anderson, D. (2003) Environmental cleanup site information (ECSI) database site summary report-details for site ID: 2491, Opalite mine, ID: 2493, Bretz mine. Oregon Department of Environmental Quality, Portland, Oregon 97204.

Jones, R., Lapp, T., and Wallce, D. (2003) Locating and Estimating Air Emissions From Sources of Mercury and Mercury Compounds, EPA Office of Air and Radiation, Report 454-R93023, 303 p.

Rytuba, J.J., John, D.A., Foster, A., Ludington, S.D. and Kotlyar, B. (2003) Hydrothermal enrichment of gallium in zones of advanced argillic alteration—examples from the Paradise Peak and McDermitt ore deposits, Nevada. In Contributions to Industrial-Minerals Research, Chapter C, Bulletin 2209-C, Bliss, J. D., Moyle, P. R., and Long, K. R., editors, 16pp.

Dunning, G.E., Hadley, T.A., Magnasco, J., Christy, A.G. and Cooper, J.F., jr. (2005) The Clear Creek mine, San Benito County, California: A unique mercury locality. Mineralogical Record, 36, 337-363.

Roberts, A.C., Gault, R.A., Paar, W.H., Cooper, M.A., Hawthorne, F.C., Burns, P.C., Cisneros, S., and Foord, E.E. (2005) Terlinguacreekite, Hg2+3O2Cl2, a new mineral species from the Perry pit, Mariposa mine, Terlingua mining district, Brewster County, Texas, USA. Canadian Mineralogist, 43,1055-1060.

Childs, J.F. (2007) Cordero gold-silver project technical report, Cordero-43-101_09-04-07-Final.pdf, Opalite Mining District, McDermitt, Nevada. (Report prepared for Silver Predator Corporation, Reno, Nevada).

Vinals, J. and Calvo, M. (2007) Corderoite, kenhsuite and perroudite, mercury sulfohalides from Chovar, Castello, Spain. Revista de Minerales. 3(3): 46-49. Barcelona, Spain.

Carew, Timothy J. (2008) NI 43-101 Technical Report and Resource Estimation for the Cordero Gallium Project, Humboldt County, Nevada, USA, prepared for Gold Canyon Resources, Inc., 35pp.

Cobble, M.A. and Mahood, G.A. (2008) New geologic evidence for additional 16.5-15.5 Ma silicic calderas in northwest Nevada related to initial impingement of the Yellowstone hot spot, IOP Publishing, Inc., Collapse Calderas Workshop, Conference 1 Volume 3, Earth and Environmental Science.

Pierce, K.L., and Morgan, L.A. (2009) Is the track of the Yellowstone hotspot driven by a deep mantle plume?—review of volcanism, faulting, and uplift in light of new data: Journal of Volcanology and Geothermal Research, v. 188, 1–25.

Stetson, S.J., Gray, J.E., Wanty, R.B. and Macalady, D.L. (2009) Isotopic variability of mercury in ore, mine-waste calcine, and leachates of mine-waste calcine from areas mined for mercury. Environmental Science & Technology, 43(19), DOI: 10.1021/es9006993 PMCID: pmc2754665, 7331-7336.

Castor, S.B. and Ferdock, G.C. (2012) Minerals of Nevada. Nevada Bureau of Mines and Geology Special Publication 31, 512 p.

Cobble, M.A. and Mahood, G.A. (2012) Initial impingement of the Yellowstone plume located by widespread silicic volcanism contemporaneous with Columbia River flood basalts, Geology, published online May 01, 2012 as doi:10.1130/G32692.1; 3 figures; Data Repository item 2012188.

Henry, C.D., Castor, S.B., Starkel, W.A., Ellis, B.S., Wolff, J.A., Heizler, M.T., McIntosh, W.C. (2012) Geologic mapping, volcanology, mineralization, and high precision 40Ar / 39Ar dating of early Yellowstone hotspot magmatism: Abstract V33B-2850 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.

Henry, C.D., and John, D.A. (2013) Magmatism, ash-flow tuffs, and calderas of the ignimbrite flareup in the western Nevada volcanic field, Great Basin, USA: Geosphere, v. 9, 951–1008.

Blumefeld, J. (2014) Environmental photo selection of McDermitt and Cordero mine areas.

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.

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