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North Keystone

Producer in Calaveras county in California, United States with commodity Copper
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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. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Reserves and resources
  17. Workings at the site
  18. Links to other databases
  19. Bibliographic references
  20. General comments
  21. Reporter information

Geologic information

Identification information

Deposit ID 10028815
MRDS ID M006029
Record type Site
Current site name North Keystone
Alternate or previous names Keystone
Related records 10260270

Geographic coordinates

Geographic coordinates: -120.64768, 37.98713 (WGS84)
Relative position NW 1/4 OF SEC. 2000' N OF THE KEYSTONE SHAFT.

Site location context

Political divisions (FIPS codes)

Calaveras(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Copperopolis(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 Calaveras

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 002N 012E 34 California

Commodities

Commodity Importance
Copper Primary

Comments on the commodity information

  • PYRITE AND CHALCOPYRITE IN MANY PLACES INTIMATELY INTERGROWN.

Materials information

Materials Type of material
Andalusite Ore
Bornite Ore
Chalcopyrite Ore
Cuprite Ore
Ilmenite Ore
Malachite Ore
Pyrite Ore
Rutile Ore
Sphene Ore
Calcite Gangue
Epidote Gangue
Hematite Gangue
Jasper Gangue
Quartz Gangue

Alteration

  • (Local) Chloritization

Analytical data

Result 1 1/2 - 9 % CU

Mineral occurrence model information

Model code 184
USGS model code 28a
Deposit model name Massive sulfide, kuroko
Mark3 model number 93

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Metasedimentary Rock > Slate
    Stratigraphic age (youngest) Late Jurassic
  • Host or associated Host
    Rock type Metamorphic Rock > Schist

Nearby scientific data

(1) -120.64768, 37.98713
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description See Comments

Ore body information

  • General form LENTICULAR
    Width 6.1M

Controls for ore emplacement

  • 1. Belt Of Intense Chloritization, 2. Chloritiz Slate And Schist. Afforded Most Favorable Envioroment For Penetration And Replacement By Copper - Bearing Solutions, Granodiorite Did Not. 3. "Footwall Fault" And Subsidiary Faults And Fissures. 4. Larger Ore Bodies Are Parallel To Segments Of "Footwall Fault" Which Have A More Northerly Strike.

Comments on the geologic information

  • GEOL.DESC: SLATE AND METAVOLCANIC ROCKS IN MINE AREA STRIKE NORTHWEST; CLEVAGE, SCHISTOSITY AND BEDDING DIP STEEPLY NORTHEAST. METAVOLCANICS INCLUDE PALE - GREEN SPOTTED SCHIST AND GREENSTONE FROM ANDESITIC AND DACITIC ROCKS, OTHERS INCLUDE DARK BLUE GRAY ARGILLACEOUS SLATY TUFFS, SCHISTOSE PYROCLASTICS, BEDDED HORNSTONE AND VOLCANIC BRECCIA. EAST OF MINE IS AN ELONGATE BODY OF SERPENTINE, SOUTH IS AN OVAL - SHAPED AREA OF SAUSSURITIZED GABBRO. 1,000 FT. NORTH OF MINE, SEVERAL DIKES OF HORNBLENDITE BRECCIA, OTHERS INCLUDE SERPENTINE, HORNBLENDITE, DIORITE AND THE MOST SIGNIFICANT A LARGE BODY OF GRANODIORITE.

Economic information about the deposit and operations

Development status Producer
Commodity type Metallic
Deposit size Large
Significant No
Production years 1861 - 1866 , 1867 , 1942 , 1943 , 1944 , 1945

Comments on the production information

  • 1867 PRODUCTION WAS NOT REPORTED

Reserves and resources

  • Type In-situ
    Estimate year 1943
    Total resources 4000mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 3 wt-pct Copper Major 1943

Comments on the reserve resource information

  • 4 HOLES DRILLED BY U.S. BUREAU OF MINES IN 1943 , OVER 2,600 FT., ALSO PRESSENCE OF THIN CHALCOPYRITE - PYRITE STRINGERS WEST OF "FOOTWALL FAULT".

Workings at the site

  • Type of workings Underground
    Length 1315.21M
    Overall depth 339.85M

Comments on the workings information

  • ONE THREE COMPARTMENT VERTICAL SHAFT - WITH SIX LEVELS; 150 , 375 , 525 , 675 , 875 AND AT 1,075 FT. MORE THAN 3,200 FT. OF DRIFTS ALONG STRIKE ON BOTH SIDES OF THE SHAFT. MINERALIZED ZONE AT 375 FT. LEVEL.

Reference information

Bibliographic references

  • Deposit

    CLARK, W. B. AND LYDON, P. A., 1962 , MINES AND MINERAL RESOURCES OF CALAVERAS COUNTY, CALIFORNIA; COUNTY REPT. 2 ; CALIF. DIV. MINES AND GEOLOGY, P. 27 .

  • Deposit

    HEYL, G. R., 1948 , ORE DEPOSITS OF COPPEROPOLIS, CALAVERAS COUNTY, CALIFORNIA; COPPER IN CALIFORNIA BULL. 144 ; DIV. OF MINES, P. 103 - 106 .

  • Deposit

    STRATEGIC MINERALS INVEST. PRELIM. MAP 3-183

  • Production

    HEYL, G. R., 1948 , P. 96 - 97 (SEE REF.)

  • Reserve-Resource

    HEYL, G. R., 1948 , P. 106 (SEE REF.)

General comments

Subject category Comment text
Deposit 3 PRINCIPAL ORE BODIES, EACH CONCORDANT WITH FOLIATION OF ENCLOSING ROCK. EN ECHELON IN PLAN. NORTH ORE BODY HAS STRIKE LENGTH OF 360 FT., MAXIMUM WIDTH 20 FT., DEPTH AT LEAST 550 FT. MIDDLE ORE BODY IS 240 FT. IN STRIKE LENGTH, MAXIMUM WIDTH OF 20 FT., EXTENDS DOWNWARD FOR 525 FT. FROM DEPTH OF 300 FT. SOUTH ORE BODY IS 285 FT. LONG, AT LEAST 650 FT. DEEP AND 15 FT. MAXMIUM WIDTH.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUN-1972 Gere, W. U.S. Geological Survey
Updater 01-JUN-1978 Fraticelli, L. A. (Albers, J.) 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.