North Keystone

The North Keystone is a copper mine located in Calaveras county, California.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Satelite View

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Site Name

Primary: North Keystone
Secondary: Keystone

Commodity

Primary: Copper

Location

State: California
County: Calaveras

Land Status

Not available

Holdings

Not available

Workings

Type: Underground

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant: N
Deposit Size: L

Physiography

General Physiographic Area: Pacific Mountain System
Physiographic Province: Cascade-Sierra Mountains
Physiographic Section: Sierra Nevada

Mineral Deposit Model

Model Name: Massive sulfide, kuroko

Orebody

Form: LENTICULAR

Structure

Type: L
Description: See Comments

Alterations

Alteration Type: L
Alteration Text: Chloritization

Rocks

Name: Slate
Role: Host
Age Type: Host Rock
Age Young: Late Jurassic

Analytical Data

Analytical Data: 1 1/2 - 9 % CU

Materials

Ore: Chalcopyrite
Ore: Sphene
Ore: Malachite
Ore: Andalusite
Ore: Rutile
Ore: Pyrite
Ore: Cuprite
Ore: Ilmenite
Ore: Bornite
Gangue: Jasper
Gangue: Epidote
Gangue: Hematite
Gangue: Quartz
Gangue: Calcite

Comments

Comment (Geology): 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.

Comment (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.

Comment (Workings): 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.

Comment (Reserve-Resource): 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".

Comment (Commodity): PYRITE AND CHALCOPYRITE IN MANY PLACES INTIMATELY INTERGROWN.

Comment (Production): 1867 PRODUCTION WAS NOT REPORTED

References

Reference (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 .

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

Reference (Deposit): STRATEGIC MINERALS INVEST. PRELIM. MAP 3-183

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

Reference (Reserve-Resource): HEYL, G. R., 1948 , P. 106 (SEE REF.)

California Gold

"Where to Find Gold in California" looks at the density of modern placer mining claims along with historical gold mining locations and mining district descriptions to determine areas of high gold discovery potential in California. Read more: Where to Find Gold in California.