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Mountain Pass Mine and Mill

Past Producer in San Bernardino county in California, United States with commodities REE, Cerium, Gold, Silver, Lead
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Ore body information
  13. Economic information about the deposit and operations
  14. Mining district
  15. Mineral rights holdings
  16. Land status
  17. Ownership information
  18. Production statistics
  19. Reserves and resources
  20. Workings at the site
  21. Links to other databases
  22. Bibliographic references
  23. General comments
  24. Reporter information

Geologic information

Identification information

Deposit ID 10212814
MRDS ID M023680
MAS/MILS ID 0060710189
Record type Site
Current site name Mountain Pass Mine and Mill
Alternate or previous names Mountain Pass Mine, Mountain Pass Bastnasite Mine, Birthday, Lucky Strike, Mineral Hill, Sulphide Queen

Geographic coordinates

Point of reference Pit
Geographic coordinates: -115.53218, 35.4786 (WGS84)
Elevation 1450
Location accuracy 10(meters)
Relative position Center of open pit

Site location context

Political divisions (FIPS codes)

San Bernardino(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Mescal Range(quadrangle 1:24,000 scale)

Ivanpah(quadrangle 1:100,000 scale)

Kingman(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ivanpah-Pahrump Valleys(hydrologic unit)

Central Nevada Desert Basins(hydrologic accounting unit)

Central Nevada Desert Basins(hydrologic subregion)

Great Basin(hydrologic region)

Geographic areas

Country State County
United States California San Bernardino

Public Land Survey System information

Meridian Township Range Section Fraction State
San Bernardino 016 N 013 E 12, 13 SENENW (13) California

Commodities

Commodity Importance
REE Critical Primary
Cerium Critical Primary
Gold Primary
Silver Secondary
Lead Tertiary

Materials information

Materials Type of material
Bastnasite Ore
Bastnaesite Ore
Monazite Ore
Apatite Ore
Barite Ore
Celestite Ore
Calcite Gangue
Dolomite Gangue
Siderite Gangue
Ankerite Gangue
Quartz Gangue
Strontianite Unknown
Galena Unknown

Alteration

  • (Local) fenitization
  • (Local) hematization

Analytical data

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

Mineral occurrence model information

Model code 24
USGS model code 10
Deposit model name Carbonatite

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Gneiss
    Stratigraphic age (youngest) Neoproterozoic

Nearby scientific data

Pit (1) -115.53218, 35.4786
ListMap

Economic information

Ore body information

  • Strike N10W
    Dip 40W
    Thickness 75M
    Length 750M
    Width 1590M
    Area 1500HA
    Depth to top 458M
    Field Value
    MAS Matrix # 1
    MAS Column # 1
    Type of Orebody #1 OTHER
    Shape of Orebody #1 TABULAR
    Type of Orebody #2 FISSURE VEIN
    Type of Orebody #3 SHEAR ZONE
    Primary mode of Origin MAGMATIC DIFFER
    Secondary mode of Origin HYDROTHERMAL
    Primary Ore Control IGNEOUS
    Secondary Ore Control FRACTURING
    Degree of Wallrock Alter. SLIGHT
    Type of Wallrock Alter. #1 SILICIFICATION
    Type of Wallrock Alter. #2 CARBONITIZATION
    Type of Wallrock Alter. #3 OTHER
    Strike And Dip N10W:40W
    Minimum Depth to Top 0
    Avg. Thick. Unconsol. Mat. 0
    Min. Thick. Unconsol. Mat. 0
    Date of Last Modification 901030

Comments on the geologic information

  • Vein at contact of dike and host rock. Aplite dike hanging wall, gneiss footwall. Dikes trend N30W

Economic information about the deposit and operations

Operation type Surface
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1949
Mining method Open Pit
Year of first production 1951
Year of last production 2002
Milling method Flotation

Mining district

District name Mountain Pass
District name Ivanpah District

Mineral rights holdings

Type of mineral rights Patented
Type of mineral rights Located Claim

Land status

Ownership category Private

Ownership information

  • Type Owner-Operator
    Owner Molybdenum Corporation of America (MCA)
    Interest 100
    Year 2010
    First year 1950
    Last year 1974
  • Type Owner-Operator
    Owner Molycorp, Inc.
    Interest 100
    Home office (same company, new name)
    Year 2010
    First year 1974
    Last year 1977
  • Type Owner
    Owner Union Oil of California
    Interest 100
    Year 2010
    First year 1977
  • Type Operator
    Owner Molycorp, Inc.
    Interest 100
    Year 2010
    First year 1977
    Last year 2005
  • Type Owner-Operator
    Owner Molycorp Minerals LLC
    ID 402542
    Interest 100
    Home office Englewood, CO
    Year 1983

Production statistics

  • Year 1982
    Description Quantity Of Reo In Bastnaesite Conc. 16780 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 16780mt
  • Year 1983
    Description Quantity Of Reo In Bastnaesite Conc. 17083 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 17083mt
  • Year 1984
    Description Quantity Of Reo In Bastnaesite Conc. 25311 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 25311mt
  • Year 1985
    Description Quantity Of Reo In Bastnaesite Conc. 13428 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 13428mt
  • Year 1986
    Description Quantity Of Reo In Bastnaesite Conc. 11094 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 11094mt
  • Year 1987
    Description Quantity Of Reo In Bastnaesite Conc. 16710 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 16710mt
  • Year 1988
    Description Quantity Of Reo In Bastnaesite Conc. 17000 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 17000mt
  • Year 1989
    Description Quantity Of Reo In Bastnaesite Conc. 20334 Mt Reo/Year
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary REE REE REE 20334mt

Comments on the production information

  • 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.
  • 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.

Reserves and resources

  • Type In-situ
    Estimate year 1989
    Indicated 28123000mt ore
    Demonstrated 28123000mt ore
    Total resources 28123000mt ore
    Commodity Subtype Grade units Group Importance Year
    REE Y Group 8.9 wt-pct REE Major 1989

Comments on the reserve resource information

  • Thorium may occur in area, although not being recovered by Molycorp at present time.

Workings at the site

  • Type of workings Surface
    Name of workings Open Pit
    Area 260HA
    Overall depth 169.16M
    Field Value
    MAS Development Schedule # 1
    Mining Record # 1
    Status of Mining Method ACTUAL
    Mining Method OPEN PIT
    Swell Factor .7
    Percent Waste Rock 50
    Avg. Overburden Thickness 69
    Primary Material Cover HARD ROCKS
    Percentage 100
    Hardness of Ore M-HARD ROCKS
    Avg. Bench Height (meters) 9
    Max. Pit Slope (degrees) 40
    Capacity 1285
    Capacity Units MT ORE/DAY
    Preprod. Stripping Vol. 0
    Unit Production Cost 7.05
    Units of Production $/MT ORE
    Operating Days per Year 240
    Operating Shifts per Day 1
    Year of Information 1990

Comments on the workings information

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

Reference information

Bibliographic references

General comments

Subject category Comment text
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.
Deposit Now included in Mt. Pass Rare-Earth Holdings. Active 1940's, 6 claims

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JAN-76 Weeks, Robert U.S. Geological Survey
Reporter 01-DEC-79 Nelson, Scott C. (Albers, John, P.) U.S. Geological Survey
Reporter 30-MAR-91 Ridenour, James U.S. Bureau of Mines
Reporter 24-JUN-96 Ritchey, Joseph L U.S. Bureau of Mines
Updater 17-NOV-10 Causey, J.Douglas U.S. Geological Survey Made minor corrections to some of the tables.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Current status (per MSHA)

StatusActive since 12/13/2017
MSHA mine ID0402542
Mine name (MSHA)Mt Pass Mine & Mill
Current operatorMP Mine Operations, LLC.
Current controller (parent)MP Materials Corporation
Mine typeSurface (Metal / non-metal)

MSHA cross-reference per the original MRDS record. Mine status and operator reflect MSHA's last published Mines export (February 2025); MSHA's public bulk feed has been unavailable since, so this may be out of date. See the Mine Data Retrieval System for current status.

Open MSHA's Mine Data Retrieval System for inspections, accidents, and violations for this mine.

Maps centered on this site

Authoritative California resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.