Mountain Pass Mine and Mill

The Mountain Pass Mine and Mill is a gold, ree, and cerium mine located in San Bernardino county, California at an elevation of 4,757 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Name: Mountain Pass Mine and Mill  

State:  California

County:  San Bernardino

Elevation: 4,757 Feet (1,450 Meters)

Primary Mineral: Gold, REE, Cerium

Lat, Long: 35.4786, -115.53218

Map: View on Google Maps

Satelite View

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Satelite image of the Mountain Pass Mine and Mill

Mountain Pass Mine and Mill MRDS details

Site Name

Primary: Mountain Pass Mine and Mill
Secondary: Mountain Pass Mine
Secondary: Mountain Pass Bastnasite Mine
Secondary: Birthday
Secondary: Lucky Strike
Secondary: Mineral Hill
Secondary: Sulphide Queen


Primary: Gold
Primary: REE
Primary: Cerium
Secondary: Silver
Tertiary: Lead


State: California
County: San Bernardino
District: Ivanpah District

Land Status

Land ownership: Private
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.


Type: Located Claim
Type: Patented


Type: Surface


Owner Name: Union Oil of California
Percent: 100.0
Info Year: 2010
Years: 1977 -

Owner Name: Molycorp Minerals LLC
Company ID: 402542
Percent: 100.0
Home Office: Englewood, CO
Info Year: 1983

Owner Name: Molycorp, Inc.
Percent: 100.0
Info Year: 2010
Years: 1977 - 2005

Owner Name: Molycorp, Inc.
Percent: 100.0
Home Office: (same company, new name)
Info Year: 2010
Years: 1974 - 1977

Owner Name: Molybdenum Corporation of America (MCA)
Percent: 100.0
Info Year: 2010
Years: 1950 - 1974


Year: 1989
Description: Quantity Of Reo In Bastnaesite Conc. 20334 Mt Reo/Year
Year: 1988
Description: Quantity Of Reo In Bastnaesite Conc. 17000 Mt Reo/Year
Year: 1987
Description: Quantity Of Reo In Bastnaesite Conc. 16710 Mt Reo/Year
Year: 1986
Description: Quantity Of Reo In Bastnaesite Conc. 11094 Mt Reo/Year
Year: 1985
Description: Quantity Of Reo In Bastnaesite Conc. 13428 Mt Reo/Year
Year: 1984
Description: Quantity Of Reo In Bastnaesite Conc. 25311 Mt Reo/Year
Year: 1983
Description: Quantity Of Reo In Bastnaesite Conc. 17083 Mt Reo/Year
Year: 1982
Description: Quantity Of Reo In Bastnaesite Conc. 16780 Mt Reo/Year


Record Type: Site
Operation Category: Past Producer
Operation Type: Surface
Mining Method: Open Pit
Milling Method: Flotation
Year First Production: 1951
Year Last Production: 2002
Discovery Year: 1949
Years of Production:
Significant: Y
Deposit Size: S


General Physiographic Area: Intermontane Plateaus
Physiographic Province: Basin And Range Province
Physiographic Section: Sonoran Desert

Mineral Deposit Model

Model Name: Carbonatite


Not available


Not available


Alteration Type: L
Alteration: hematization

Alteration Type: L
Alteration: fenitization


Name: Gneiss
Role: Host
Age Type: Host Rock
Age Young: Neoproterozoic

Analytical Data

Analytical Data: ORE SHOOT 100 FT LONG, 12-15 FT THICK, SAID TO CARRY $9.00 AU/TON


Ore: Apatite
Ore: Monazite
Ore: Bastnasite
Ore: Barite
Ore: Bastnaesite
Ore: Celestite
Gangue: Dolomite
Gangue: Siderite
Gangue: Ankerite
Gangue: Quartz
Gangue: Calcite
Unknown: Strontianite
Unknown: Galena


Comment (Reserve-Resource): Thorium may occur in area, although not being recovered by Molycorp at present time.

Comment (Production): An estimated production rate in the 1980's was 1,285 mt/day including 1,155 mt/day ore and 130 mt/day of dilution material.

Comment (Deposit): Water is obtained from wells 10km east of the mine. Power is supplied by Southern California Edison Co. The access road is paved and labor is available at the site.

Comment (Geology): Vein at contact of dike and host rock. Aplite dike hanging wall, gneiss footwall. Dikes trend N30W

Comment (Deposit): Now included in Mt. Pass Rare-Earth Holdings. Active 1940's, 6 claims

Comment (Workings): (Sulfide Queen) 365 Ft. incline w/4 levels comprising about 2000 ft. of drifts and crosscuts. Detailed descriptions of workings in Tucker & Sampson (1943)

Comment (Production): The production numbers are amount of REE's in the concentrate. This is not the same as the total recovered since there is some loss in processing the concentrate. True production is somewhat less, but loss in processing is not reported.


Reference (Deposit): Woyski, Margaret S., 1980, Petrology of the Mountain Pass carbonatite complex - A review, in Geology and mineral wealth of the California Desert, Fife, D.L. and Brown A.R., Eds., South Coast Geological Society
Pages: p. 367-378

Reference (Deposit): Warhol. W. N. Rare Earths And The Mountain Pass, California Operations. SME-AIME, Pre-Print No. 80-380, Oct. 1980, 7 p.

Reference (Deposit): Warhol, W. N. Molycorp's Mountain Pass Operations, In Fife, D. L., And A. R. Brown, Eds., Geology And Mineral Wealth Of The California Desert. South Coast Geol. Soc., 1980
Pages: pp. 359-366

Reference (Deposit): Bureau Of Mines. Mineral Commodity Summaries. U.S. Dept. Interior, 1983
Pages: pp. 124-125

Reference (Deposit): Wilson. T. A. Rare Earths From Lighter Flints To X-Rays. SME-AIME Annual. Meeting Pre-Print No. 82-52, Feb. 1982, 3 p.

Reference (Deposit): National Oceanic And Atmospheric Administration. Climates Of The States, V. 2, Western States. U.S. Dept. Commerce, 1974
Pages: pp. 538-594.

Reference (Deposit): Morrice, E. And M. M. Wong. Flotation Of Rare Earths From Bastnaesite Ore. Bumines RI 8689, 1982, 13 p.

Reference (Deposit): Industrial Minerals. Minerals In The U.S. South-West: Breaking Rocks In The Hot Sun. Industrial Minerals, No. 272, May 1990
Pages: pp 79-83

Reference (Deposit): Lindsey, D. S. Mountain Pass Mine, Mountain Pass District, San Bernardino County, Ca. Bumines File Report, September 1978.

Reference (Deposit): Calif. Jour. Mines And Geol., V. 49, 1953, Tabulated List, No. 189
Pages: p. 58-59

Reference (Deposit): Olsen, J.C., and Pray, L.C., 1954, The Mountain Pass rare earth deposits, in The Geology of Southern California, Calif. Bureau of Mines and Geology Bull. 170
Pages: p. 23-29

Reference (Deposit): Hewett. D. F. History Of The Discovery At Mountain Pass, California, In Olson, J. C., And Others, Rare-Earth Mineral Deposits Of The Mountain Pass District, San Bernardino County, Ca. U.S. Geological Survey Prof. Paper 261, 1954
Pages: pp. III-VI

Reference (Deposit): Hewett, D.F., 1956, Geology and mineral resources of the Ivanpah quadrangle, California and Nevada: U.S. Geol. Survey Professional Paper 275, 172 p.

Reference (Deposit): Ceramic News. New Rare Earth Processing Plant. August, 1965
Pages: pp. 10, 13

Reference (Deposit): Parkhurst, D. The Mountain Pass Rare Earth Project. Ca Mining Jour., Mar. 1983
Pages: Pp. 72-75

Reference (Deposit): Ritchey, J. L. Mountain Pass Mine, San Bernardino County, Ca. Bumines MAS Property Evaluation File Report, Sept. 1983, 27 p.

Reference (Deposit): Olson, J. C., D. R. Shawe, L. C. Pray, And W. N. Sharp. Rare-Earth Mineral Deposits Of The Mountain Pass District, San Bernardino County, Ca. U.S. Geological Survey Prof. Paper 261, 1954, 75 p.

Reference (Deposit): Bureau Of Mines. Bureau Of Mines Cost Estimating System Handbook. Bumines IC 9142, Vols. 1 And 2, 1987.

Reference (Deposit): Sharp, W. N., And L. C. Pray. Geologic Map Of Bastnaesite Deposits Of The Birthday Claims, San Bernardino County, Ca. U.S. Geological Survey Map Mf-4, 1952, Scale 1:600.

Reference (Deposit): _____. Relationship Of Mineralization To Major Structural Features In The Mountain Pass Area, San Bernardino County, Ca. Ca Geol., July 1974
Pages: pp. 147-155

Reference (Deposit): Fuerstenau, D. W., Pradip, L. A. Kahn, S. Raghavan. Alternate Reagent Scheme For The Flotation Of Mountain Pass Rare-Earth Ore. Pre-Prints - Xiv International Processing Conference. Publ. By Cim, Montreal, Quebec, 1983.

Reference (Deposit): Wright, L. A., And Others. Mines And Mineral Deposits Of San Bernardino County, CA. CA Jour. Mines And Geol., V. 49, 1953
Pages: pp. 121-125

Reference (Deposit): Evans. J. R. California'S Mountain Pass Mine Now Producing Europium Oxide. Ca Div. Mines And Geol., Mineral Inf. Service, V. 18, Feb. 1966, Pp. 23-32.

Reference (Deposit): Long, K.R., Van Gosen, B.S., Foley, N.K., and Cordier, Daniel, 2010, The Principal Rare Earth Elements Deposits of the United States?A Summary of Domestic Deposits and a Global Perspective; USGS Scientific Investigations Report 2010-5220.

Reference (Deposit): Jessey, David, 2011, The Mountain Pass Mine; webpage accessed 9/10/2011.

Reference (Deposit): Burchfiel, B.C., and Davis, G.A., 1988, Mesozoic thrust faults and Cenozoic low-angle normal faults, eastern Spring Mountains Nevada, and Clark Mountains thrust complex, California in This Extended Land: Geological journeys in the southern Basin and Range, Field Trip Guidebook, Geological Society of America, Western Cordilleran Section, Las Vegas, Nevada
Pages: p. 87-10

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