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Richards Mine

Past Producer in Tuolumne 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. Land status
  16. Ownership information
  17. Production statistics
  18. Links to other databases
  19. Bibliographic references
  20. General comments
  21. Reporter information

Geologic information

Identification information

Deposit ID 10043707
MRDS ID M100612
Record type Site
Current site name Richards Mine
Alternate or previous names Rough and Ready Mine 1918

Geographic coordinates

Geographic coordinates: -120.49239, 37.90825 (WGS84)
Elevation 381
Relative position APPROX. 8 MILES SW OF SONORA, CA.

Site location context

Political divisions (FIPS codes)

Tuolumne(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Sonora(quadrangle 1:24,000 scale)

Oakdale(quadrangle 1:100,000 scale)

San Jose(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Stanislaus(hydrologic unit)

San Joaquin(hydrologic accounting unit)

San Joaquin(hydrologic subregion)

California(hydrologic region)

Geographic areas

Country State County
United States California Tuolumne

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 001N 013E 25 California

Commodities

Commodity Importance
Chromium Critical Primary

Comments on the commodity information

  • ASSAY OF HIGH GRADE ORE SHIPPED DURING WWI.

Materials information

Materials Type of material
Chromite Ore

Alteration

  • (Local) Serpentinization And Silicification Of Host Rock.

Analytical data

Result 36.7% CR2O3

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Dunite
    Rock unit name Calaveras
    Rock description Calaveras
    Stratigraphic age (youngest) Late Jurassic
    Stratigraphic age (youngest) Late Permian

Nearby scientific data

(1) -120.49239, 37.90825
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description Bear Mountain Fault Zone Trending Nw
Type of structure Local
Structure description Shearing In Host Rock Strongly Developed In A N 65-75 W Direction.

Ore body information

  • General form LENSE
    Strike N 60-70 W
    Dip SW
    Width 1.83M

Comments on the geologic information

  • THE DEPOSIT OCCURS IN THE NORTHERN PART OF THE WESTERNMOST OF TWO SERPENTINE BELTS THAT TREND NW-SE ACROSS THE COUNTY. THE BELT IS EXPOSED OVER AN AREA. 30 KM BY 6 KM.

Economic information about the deposit and operations

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

Mining district

District name Peoria Flat Area

Land status

Ownership category Private

Ownership information

  • Type Operator
    Owner Bradley Mining Co.
    First year 1942
  • Type Owner
    Owner Otis Rosasco,
    Home office Star Route, Box 150, Jamestown, Ca. 95327.

Production statistics

  • Year 1918
    Material ORE
    Accuracy Estimate
    Description Ap_Grade: ^36.7% Cr2o3
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major Cr2O3 Chromium Chromium 37wt-pct

Comments on the workings information

  • WORKINGS CONSISTED OF AN OPEN CUT 180 FT LONG, 20-30 FT WIDE, 10-20 FT DEEP, TRENDING N 60 W, TWO SHORT ADITS DRIVEN NIDE AND S 60 E, AND SEVERAL SHALLOW PROSPECT TRENCHES (1975).

Reference information

Bibliographic references

  • Deposit

    STINSON, M. C., 1975, CDMG MINERAL PROPERTY REPORT, UNPUBLISHED

  • Deposit

    CATER, F. W. JR., 1948, CDMG BULL 134, PART 3, CHAPT. 1, P. 27, 28.

  • Production

    CDMG MINERAL PROPERTY REPORT, UNPUBLISHED

General comments

Subject category Comment text
Deposit AN ORE ZONE, AS DESCRIBED ABOVE, WAS EXPOSED IN THE FLOOR AND NORTH WALL OF THE MAIN PIT.

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.

External references

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.