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Horseshoe Claim, Grassely Group

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. Ore body information
  12. Economic information about the deposit and operations
  13. Mining district
  14. Ownership information
  15. Reserves and resources
  16. Links to other databases
  17. Bibliographic references
  18. General comments
  19. Reporter information

Geologic information

Identification information

Deposit ID 10098575
MRDS ID M100605
Record type Site
Current site name Horseshoe Claim, Grassely Group
Alternate or previous names Pedro Lease 1918

Geographic coordinates

Geographic coordinates: -120.50517, 37.90436 (WGS84)
Elevation 326
Relative position APPROX. 10.5 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

New Melones Dam(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 N2 California

Comments on the location information

  • MINE IS LOCATED ON THE NW SIDE OF A SMALL HILL.

Commodities

Commodity Importance
Chromium Critical Primary

Materials information

Materials Type of material
Chromite Ore

Alteration

  • (Local) Serpentinization Of Saxonite

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 Jurassic
    Stratigraphic age (youngest) Late Permian

Nearby scientific data

(1) -120.50517, 37.90436
ListMap

Economic information

Ore body information

  • General form LENSE
    Strike N 15-25 W
    Dip 20 SW
    Length 15M
    Width 1M

Comments on the geologic information

  • THE DEPOSIT OCCURS IN THE NORTHERN PART OF THE WESTERN MOST 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
Year of first production 1914
Year of last production 1944

Mining district

District name Peoria Flat Area

Ownership information

  • Type Operator
    Owner George Everhart
  • Type Owner
    Owner Grassley, Eugene

Reserves and resources

  • Type Milling
    Estimate year 1975
    Commodity Subtype Grade units Group Importance Year
    Chromium Cr2O3 22 wt-pct Chromium Major 1975

Comments on the reserve resource information

  • CDMG MINERAL PROPERTY REPORT, UNPUBLISHED

Comments on the workings information

  • WORKINGS CONSISTED OF AN OPEN PIT AND A 40 FT DEEP SHAFT

Reference information

Bibliographic references

  • Deposit

    CATER, F.W. JR., 1948, CDMG BULL 134, PART 3, CHAPT. 1, P. 26,27

  • Deposit

    STINSON, M.C., 1975, CDMG MINERAL PROPERTY REPORT, UNPUBLISHED.

  • Production

    CDMG BULL 134, PT. 3, CHAPT. 1, P. 27

General comments

Subject category Comment text
Deposit ORE ZONE HAS ABOVE DIMENSIONS AND AVERAGES APPROX. 35% CR2O3

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUL-1982 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.