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Keystone Group

Past Producer in Inyo county in California, United States with commodities Copper, Lead, Silver, Gold
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Geologic information

Identification information

Deposit ID 10033982
MRDS ID M020642
Record type Site
Current site name Keystone Group
Alternate or previous names Darwin-Keystone
Related records 10285394

Geographic coordinates

Geographic coordinates: -117.56534, 36.2608 (WGS84)
Relative position 1.75 MILES SE OF DARWIN
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Geographic areas

Country State County
United States California Inyo

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 019S 041E 19,20,29,30 California

Commodities

Commodity Importance
Copper Primary
Lead Secondary
Silver Secondary
Gold Secondary

Materials information

Materials Type of material
Galena Ore
Calcite Gangue
Jasper Gangue
Limonite Gangue

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone

Nearby scientific data

(1) -117.56534, 36.2608
ListMap

Geologic structures

Type of structure Local
Structure description Folds, Faults

Ore body information

  • Strike N
    Dip 60 W
    Thickness 3.05M

Comments on the geologic information

  • GEOL.DESC: MINE IS ON FOLDED AND FAULTED ROCK OF KEELER CANYON FORMATION. ROCKS ARE BROWN-WEATHERING SILTY LIMESTONE AND BLUE-GRAY LIMESTONE. LIMESTONE IS PARTLY ALTERED TO CALC-HORNFELS. DOMINANT FAULTS TREND BETWEEN N 70 E AND EAST, DIP STEEPLY.

Economic information

Economic information about the deposit and operations

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

Mining district

District name Darwin

Production statistics

  • Year 1941
    Period 1940 - 1941
    Material ORE
    Accuracy Accurate
    Description Ap_Grade: ^.04 Oz Au/Ton, 27.9 Oz Ag/Ton, 25 % Pb, .6 % Zn, 20 % Iron.
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Trace Ore Silver Silver 788g/mt
    Ore Gold Gold 1g/mt
    Ore Iron Iron 20wt-pct
    Trace Ore Lead Lead 25wt-pct
    Trace Ore Zinc Zinc 1wt-pct

Comments on the production information

  • REPORTED: 800 TONS OF SORTED ORE SHIPPED FROM LOWER WINZE AND ZONE BETWEEN THE TWO WORKINGS, ORE AVERAGED 15 % PB, 28 OZ AG/TON, MINOR GOLD.

Comments on the workings information

  • LOWER WORKINGS; KEYSTONE ADIT, 626 FT. LONG, DRIFT 210 FT. LONG, 120 FT. OF CROSSCUTS, A 175 FT. STEEPLY INCLINED WINZE, SMALL STOPES. UPPER WORKINGS; MCDONALD ADIT. CAVED 145 FT. FROM PORTAL, 135 FT. OF DRIFTS, MINOR CROSSCUTS.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS M020642

Bibliographic references

  • Deposit

    HALL, W. E. AND MACKEVETT, E. M., 1958 , ECONOMIC GEOLOGY OF THE DARWIN QUADRANGLE, INYO COUNTY, CALIFORNIA; DIV. OF MINES, SPECIAL REPORT 51 ; P. 31 - 32

  • Production

    HALL & MACKEVETT, 1958 , P. 32 (SEE REF.)

General comments

Subject category Comment text
Deposit ORE IS HIGHLY OXIDIZED - POORLY EXPOSED, 2 - 10 FT. THICK. HAS BEEN EXPLOITED FOR STRIKE LENGTH OF 40 FT. UNDERGROUND.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUL-1978 Fraticelli, L. A. (Albers, J.) U.S. Geological Survey