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Mountain Pass Mine (Mountain Pass deposit; Bastnaesite deposit; Bastnäsite deposit; Mountain Pass carbonatite), Mountain Pass, Clark Mountain Sub-District, Clark Mts (Clark Mountain Range), Ivanpah District (Copper World District), San Bernardino Co., California, USA

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A REE deposit/mine located in secs. 12 & 13, T16N, R13E, SBM, at Mountain Pass, immediately N of Interstate highway 15, and about 15 miles W of the Nevada state line. NOTE: The mine ceased active mining in 2002 due to environmental concerns, however the owners, Molycorp Inc., have indicated they plan to return to full production in 2011. Start-up mining activities began in August 2012. In June 2015, however, Molycorp filed for bankruptcy.
Collecting is not allowed.

Mineralization involves vein baryte deposits with rare-earth minerals in metamorphic and igneous rocks of Precambrian age. One of the worlds largest lanthanide deposits. There are strong environmental concerns as this mine is situated next to the Mojave National Preserve.

Carbonatite complex (1.4 BP intrusion) intruded in Precambrian biotite-garnet-sillimanite-hornblende gneisses, biotite granitic gneisses, augen granitic gneisses and schists. The carbonatite complex is composed of eight 100 to 2000 meter-long plugs of alkaline intrusive rocks (from shonkinites and syenites to carbonatites) and about 200 dikes of carbonatite in NW-trending rows.

Alteration: fenitization and hematization.

Analysis of the bastnäsite-(Ce) by Hoffman et al. (1971) have confirmed the presence of plutonium-244 isotope. However, Sakamoto (1974) has suggested, that the source of this exotic isotope may be extraterrestrial.

Mineral List

Mineral list contains entries from the region specified including sub-localities

62 entries listed. 44 valid minerals. 1 (TL) - type locality of valid minerals.

Localities in this Region

  • California
    • San Bernardino Co.
      • Ivanpah District (Copper World District)
        • Clark Mts (Clark Mountain Range)

The above list 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.


Anonymous (1950), Rare earth deposits found in California: California Division of Mines, Mineral Information Service: 3(1): 1.

Anonymous (1950), New products: Mineral Notes & News No. 158: 1-18.

Chesterman, C.W. (1950b), Uranium, thorium and rare-earth elements: California Division Mines Bulletin 156: 361-363.

Olson, Jerry Chipman & William N. Sharp (1951), Geologic setting of the Mountain Pass bastnaesite deposits, San Bernardino County, California: abstract): Geological Society of America Bulletin: 62: 1467.

Pray, Lloyd Charles & William N. Sharp (1951), Bastnaesite discovered near Mountain Pass, California: (abstract): Geological Society of America Bulletin: 62: 1519.

Olson, Jerry Chipman (1952), Preliminary report to accompany the geologic map of the Mountain Pass district, San Bernardino County, California: USGS open file report.

Zadra, J.B., et al (1952), Concentration of bastnaesite and other cerium ores: US Bureau of Mines Report of Investigation 4919.

Donnay, Gabrielle & J.D.H. Donnay (1953), The crystallography of bastnaesite, parasite, roetgenite and synchosite: American Mineralogist: 38: 932-965.

Jaffe, H.W., et al (1953), Sahamalite, a new rare earth carbonate mineral, American Mineralogist: 38: 721-754.

Wright, L.A., et al (1953), Mines and mineral resources of San Bernardino County, California: California Journal of Mines and Geology, California Division of Mines (Report 49): 49(1-2): 125.

Olson, Jerry Chipman & Lloyd Charles Pray (1954), The Mountain Pass rare earth deposit: California Division Mines & Geology Bulletin 170, chap. VIII: 23-30.

Olson, Jerry Chipman, Shawe, D.R., Pray, L.C., Sharpe, W.N., and Hewlett, D.F. (1954), Geology of the rare-earth deposits of the Mountain Pass district, San Bernardino County California, USGS 261 pp.: 33, 34, 36, 37, 38.

Jaffe, Howard William (1955) Precambrian monazite and zircon from the Mountain Pass rare-earth district, San Bernardino County, California. Geological Society of America Bulletin: 66: 1247-1256.

Glass, Jewell Jeannette, H.T. Evans, Jr., M.K. Carron & Harry Rose, Jr. (1956), Cerite from Mountain Pass, San Bernardino County, California: American Mineralogist: 41: 665.

Jaffe, Howard William (1956) Application of the rule of Gladstone and Dale to minerals. American Mineralogist: 41: 764.

Walker, G.W., Lovering, T.G., and Stephens, H.G. (1956), Radioactive Deposits in California: Special Report 49 of the California Division of Mines & Geology: 22, 24.

Gay, Peter (1957), The crystallography of cerite: American Mineralogist: 42: 429-432.

Brobst, D.A. (1958), Barite Resources of the United States, USGS Bulletin 1072-B: 108 (Table 10).

Glass, Jewell Jeannette, H.T. Evans, Jr., M.K. Carron & F.A. Hildebrand (1958), Cerite from Mountain Pass, San Bernardino County, California: American Mineralogist: 43: 460-480.

Kreusi, P.R. and Duker, G. (1965) Production of rare-earth chloride from bastnaesite. Journal of Metals: 17: 847-849.

Adams, J.W. (1966), Rare earths, California Division Mines & Geology Bulletin 191: 350-355.

Evans, James R. (1966a) California Mountain Pass mine now producing europium oxide. California Division Mines and Geology Mineral Information Service: 18: 23-32.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 60, 79, 98, 99, 123, 125, 271, 284, 326, 389.

Weber, F.H., Jr. (1966b), Mineral resources of California: Barite. California Division of Mines and Geology Bulletin: 191: 94-98.

Pings, W.B. (1969) The rare earths today. Colorado School of Mines Mineral Industries Bulletin: 12(2) 1-19.

Hoffman, D.C., Lawrence, F.O., Mewherter, J.L., Rourke, F.M. (1971): Detection of Plutonium-244 in Nature. Nature: 234: 132-134.

Davis, Fenelon Francis and J.R. Evans (1973) Mining activity in California, July 1972 through June 1973. California Division Mines and Geology California Geology: 26: 291-305.

Woodmansee, W.C. (1973) The mineral industry of California: Reprint from 1971. U.S. Bureau of Mines Minerals Yearbook, 50 pp.: 40.

Evans, James R. (1974) Relationship of mineralization to major structural features in the Mountain Pass area, San Bernardino County, California. California Division Mines and Geology, California Geology: 27: 149-157.

Sakamoto, K. (1974): Possible cosmic dust origin of terrestrial plutonium-244. Nature: 248(5444): 130-132.

Jones, A.P. and Wyllie, P.J. (1983) Low temperature glass quenched from a synthetic rare earth carbonatite: implications for the origin of the Mountain Pass deposit, California. Economic Geology: 78: 1721-1723.

Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 183, 212, 221, 222, 294, 316-317, 318, 340, 404, 429, 462-463, 479, 486.

De Witt, E., Kwak, L.M., and Zartman, R.E. (1987) U-Th-Pb and 40Ar/39Ar dating of the Mountain Pass carbonatite and alkalic igneous rocks, southeastern California. Geological Society of America, Abstract of Programs: 19: 642.

Haxel, G. (2005) Ultrapotassic rocks, carbonatite and rare earth element deposit, Mountain Pass, southern California. In: Geology and Mineral Resources of the Mojava National Preserve, southern California. USGS Bulletin 2160.

Theodore, Ted G. (2007) Geology and Mineral Resources of the East Mojave National Scenic Area, San Bernardino County, California; USGS Bulletin 2160.

Berger, V.I., Singer, D.A., and Orris, G.J. (2009): Carbonatites of the World. Explored Deposits of Nb and REE - Database and Grade and Tonnage Models. USGS Open-File Report 09-1139.

Mariano, A. N. & Mariano, A., Jr. (2012): Rare earth mining and exploration in North America. Elements: 8: 369-376.

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