The Keystone-Union 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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Keystone-Union MRDS details
Site Name
Primary: Keystone-Union
Secondary: Calaveras Copper
Commodity
Primary: Copper
Secondary: Silver
Secondary: Gold
Location
State: California
County: Calaveras
District: Copperopolis Mines
Land Status
Not available
Holdings
Not available
Workings
Type: Underground
Ownership
Not available
Production
Year: 1861
Time Period: 1861 -
Material type: ORE
Description: Cp_Grade: ^317 Oz Au, 28,945 Oz Ag 62,600 ,131 Lbs Cu.
Deposit
Record Type: Site
Operation Category: Producer
Deposit Type: Replacement
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: Fault; East Dipping On Eastern Boundary Of Serpentine Body. Appears Continuous With "Footwall Fault" Of North Keystone Mine. Talcose Gouge With Disseminated Magnetite. Displacement Decreases Southward, 100 Ft. Displacement, Quartz Diorite Intrusion Near Stockton Road.
Alterations
Alteration Type: L
Alteration Text: Chloritization
Rocks
Name: Serpentinite
Role: Associated
Age Type: Host Rock
Age Young: Late Jurassic
Analytical Data
Analytical Data: TENOR
Analytical Data: 1 - 18 % CU, MOST HIGHER THAN 2 %
Materials
Ore: Chalcopyrite
Ore: Pyrite
Gangue: Quartz
Comments
Comment (Geology): GEOL.DESC: SIMILAR TO THE NORTH KEYSTONE MINE AREA, DARK BLUE-GRAY ARGILLACEOUS SLATE, GREEN SCHIST AND GREENSTONE, BEDDED TUFF, HORNSTONE AND VOLCANIC BRECCIA. MOST HAVE WELL DEVELOPED SCHISTOSITY OR CLEVAGE DIPPING STEEPLY EASTWARD. 200 FT. WEST IS LARGE GRANODIORITE INTRUSION, LENTICULAR, 2,000 FT. LONG, 240 FT. WIDE. SERPENTINE BODY 1,730 FT. LONG AND 85 FT. WIDE LIES EAST OF GRANODIORITE BODY.
Comment (Deposit): ADD. REF.NO.4. CALIF. B. 145, PL. 2; V. 53, NOS. 3 & 4, P. 427; EC. MIN. MAP NO. 7, 1957; COUNTY REPT. NO. 2, P. 24-27, 131 AND PL. D; USGS MR-34; MANUAL OF WAR MINERALS OF COUNTIES OF NORTHERN CALIFORNIA, 2ND ED., SEPT. 1, 1944, P. 26; CALIF. B. 176, P. 170, 171, 174
Comment (Workings): 6 SHAFTS; NORTH TO SOUTH, 1)KEYSTONE-DISCOVERY, 2)KEYSTONE, 3)UNION NO. 1, 4)UNION NO. 2, 5)UNION NO. 3, 6)SOUTH UNION. DEVELOPED ALONG 2,000 FT. LENGTH OF MINERALIZED ZONE.
Comment (Deposit): ORE BODIES LIE PARALLEL TO FOLIATION, STEEP NORTH RAKE, PITCH LENGTH 600 FT OR 1200 FT.
Comment (Production): MORE DETAIL PRODUCTION VALUES CAN BE OBTAINED IN HEYL, G.R., 1948 , P. 96 - 97 .
References
Reference (Deposit): HEYL, G.R., 1948 , ORE DEPOSITS OF COPPEROPOLIS, CALAVERAS COUNTY, CALIFORNIA; COPPER IN CALIFORNIA BULL. 144 ; DIV. OF MINES, P. 106 - 108 , P. 96 - 97 .
Reference (Deposit): EC. MINERAL MAP NO. 6
Reference (Production): HEYL, G.R., 1948 , P. 96 - 97 (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.
