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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. Host and associated rocks
  9. Nearby scientific data
  10. Geologic structures
  11. Economic information about the deposit and operations
  12. Mining district
  13. Land status
  14. Ownership information
  15. Links to other databases
  16. Bibliographic references
  17. General comments
  18. Reporter information

Geologic information

Identification information

Deposit ID 10043702
MRDS ID M100606
Record type Site
Current site name Grassely Group
Alternate or previous names Claims: Last Chance, Morning Glory, May Faction, Lopez 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

Commodities

Commodity Importance
Chromium Critical Primary

Materials information

Materials Type of material
Chromite Ore

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Dunite
    Stratigraphic age (youngest) Late Jurassic

Nearby scientific data

(1) -120.50517, 37.90436
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description Serpentinization Of Dunite
Type of structure Regional
Structure description Extensive Shearing In Host Rock

Comments on the geologic information

  • DEPOSIT OCCURS IN 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 1917

Mining district

District name Peoria Flat Area

Land status

Ownership category Private

Ownership information

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

Comments on the workings information

  • WORKINGS ON THE 3 CLAIMS CONSISTED OF SMALL TRENCHES, PITS, OPENCUTS AND SHALLOW CAVED SHAFTS.

Reference information

Bibliographic references

  • Deposit

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

  • Production

    CDMG BULL 134, PT. 3, CHAPT. 1, P. 26, 27.

General comments

Subject category Comment text
Deposit DEPOSIT CONSISTS OF VERTICALLY DIPPING BANDS OF CHROMITE THAT STRIKE NW, EXCEPT AT THE MAY FACTION CLAIM WHERE THE ORE BANDS STRIKE N12W AND THE LIREATION OF THE ORE PITCHES 10 SE.

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.