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
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North Keystone MRDS details
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.
