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O'Brien Mine

Past Producer in El Dorado county in California, United States with commodity Chromium
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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. Host and associated rocks
  10. Nearby scientific data
  11. Geologic structures
  12. Ore body information
  13. Economic information about the deposit and operations
  14. Mining district
  15. Ownership information
  16. Production statistics
  17. Links to other databases
  18. Bibliographic references
  19. Reporter information

Geologic information

Identification information

Deposit ID 10098579
MRDS ID M100636
Record type Site
Current site name O'Brien Mine
Alternate or previous names S-Bend Mine

Geographic coordinates

Geographic coordinates: -121.89744, 38.826 (WGS84)
Elevation 439
Relative position 18 MI S OF AUBURN, CA.

Site location context

Political divisions (FIPS codes)

Yolo(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Zamora(quadrangle 1:24,000 scale)

Sacramento(quadrangle 1:100,000 scale)

Sacramento(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Sacramento-Stone Corral(hydrologic unit)

Lower Sacramento(hydrologic accounting unit)

Sacramento(hydrologic subregion)

California(hydrologic region)

Geographic areas

Country State County
United States California El Dorado

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 011N 010E 06 SE California

Comments on the location information

  • LOCATED ON STEEP, SE FACING HILLSIDE

Commodities

Commodity Importance
Chromium Critical Primary

Materials information

Materials Type of material
Chromite Ore
Talc Gangue

Alteration

  • (Local) Serpentinization, Chloritization

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Late Cretaceous
  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Dunite
  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Harzburgite
    Rock unit name Amador Group;Calaveras Group
    Rock description Amador Group;Calaveras Group
  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Pyroxenite

Nearby scientific data

(1) -121.89744, 38.826
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description A Fault With Considerable Apparent Displacement Is Exposed In Lower Adit And On Surface.

Ore body information

  • General form POD, LENS
    Width 6.1M

Comments on the geologic information

  • MINE OCCURS IN ULTRAMAFIC MASS EXPOSED IN WESTERN METAMORPHIC BELT OF SIERRA NEVADA FOOTHILLS.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant No

Mining district

District name Garden Valley Area

Ownership information

  • Type Owner
    Owner Margaret Bell, Grass Valley, Ca

Production statistics

  • Year 1942
    Period 1918-1942
    Material ORE
    Accuracy Estimate
    Description Cp_Grade: ^32-34% Cr2o3
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Cr2O3 Ore Chromium Chromium 33wt-pct

Comments on the workings information

  • WORKINGS CONSIST OF TWO ADITS, A GLORY HOLE, AND A SHALLOW WINZE.

Comments on development

  • MINE LAST OPERATED 1942 BY VOLO MINING CO.

Reference information

Bibliographic references

  • Deposit

    STINSON, M.C., 1976, MINERAL PROPERTY REPORT, CDMG UNPUBLISHED REPORT.

  • Deposit

    CDMG BULL 134, PT. 3, CHPT. 4, P. 156

  • Production

    CDMG BULL 134, P. 156

  • Reserve-Resource

    CDMG BULL 134, P. 156.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUL-1980 Oster, Karel L. (Albers, John P.) U.S. Geological Survey

Beyond USGS

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

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.