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Copper Hill Mine (Cosumnes Mine; Hobo Mine; Jackass shaft), Four Corners, Amador County, California, USAi
Regional Level Types
Copper Hill Mine (Cosumnes Mine; Hobo Mine; Jackass shaft)Mine
Four Corners- not defined -
Amador CountyCounty
CaliforniaState
USACountry

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Latitude & Longitude (WGS84):
38° 30' 7'' North , 120° 58' 0'' West
Latitude & Longitude (decimal):
Type:
Nearest Settlements:
PlacePopulationDistance
Plymouth960 (2017)10.8km
Rancho Murieta5,488 (2011)11.1km
Drytown167 (2011)11.9km
Amador City189 (2017)15.4km
Ione7,000 (2017)16.8km
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
ClubLocationDistance
Amador County Gem & Mineral SocietySutter Creek, California19km
El Dorado County Mineral and Gem SocietyPlacerville, California29km
Gold Country Treasure SeekersPlacerville, California29km
Roseville Rock RollersRoseville, California39km
Fossils for Fun Society, Inc.North Highlands, California41km
Mindat Locality ID:
73552
Long-form identifier:
mindat:1:2:73552:5
GUID (UUID V4):
c854d8e0-a0f5-4ae7-8f6c-f658fe2a93e4


A former Cu-Au-Zn-Ag mine located in the SEΒΌ sec. 34, T8N, R9E, MDM, 3.8 km (2.4 miles) NW of Four Corners. MRDS database stated accuracy for this location is 100 meters.

NOTE: There is a third USGS MRDS database file which quite apparently pertains to this locality. That file is also named "Copper Hill" and is #10114448, which also provides a second MAS-MILS file #0060050540, and places it in sec. 3, T7N, R9E, MDM. That T&R section is contiguous to sec. 34, T8N, R9E, on its S. The only additional reference provided is the USGS crib list. The error here is apparently in the latitude value since it is otherwise directly S of the actual Copper Hill Mine location (same longitude).

Mineralization is a massive sulphide deposit (Deposit Model: 184: Massive sulfide, kuroko), hosted in rocks of the (amphibolite, and Late Jurassic schist of the Logtown Ridge Formation). The ore body is lenticular in shape, strikes NW and dips 60NE. Controls for ore emplacement included a shear and brecciated zone in Logtown Ridge metavolcanic rocks. Local rocks include Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains).

Workings include underground openings with an overall depth of 213.36 meters and a length of 1,584.96 meters. There are over 1,200 feet of shafts and over 1,800 feet of drifts. The main shaft is on the Cosumnes.

This mine was a large Cu producer in the past. The U.S. Bureau of Mines disclosed 3 separate lenses of ore in an undeveloped block during 1943, after 2,864 feet of diamond drilling. One drill hole NE of the Jackass shaft assayed 22.37% Zn, 0.43% Cu, 9.31 ounces/ton Ag, and 0.02 ounce Au/ton.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Mineral List


8 valid minerals.

Detailed Mineral List:

β“˜ Azurite
Formula: Cu3(CO3)2(OH)2
β“˜ Bornite
Formula: Cu5FeS4
β“˜ Chalcocite
Formula: Cu2S
β“˜ Chalcopyrite
Formula: CuFeS2
Description: Principal ore mineral here.
β“˜ Epsomite
Formula: MgSO4 · 7H2O
β“˜ Malachite
Formula: Cu2(CO3)(OH)2
β“˜ Pyrite
Formula: FeS2
β“˜ Sphalerite
Formula: ZnS

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
β“˜Chalcocite2.BA.05Cu2S
β“˜Bornite2.BA.15Cu5FeS4
β“˜Sphalerite2.CB.05aZnS
β“˜Chalcopyrite2.CB.10aCuFeS2
β“˜Pyrite2.EB.05aFeS2
Group 5 - Nitrates and Carbonates
β“˜Azurite5.BA.05Cu3(CO3)2(OH)2
β“˜Malachite5.BA.10Cu2(CO3)(OH)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
β“˜Epsomite7.CB.40MgSO4 Β· 7H2O

List of minerals for each chemical element

HHydrogen
Hβ“˜ AzuriteCu3(CO3)2(OH)2
Hβ“˜ EpsomiteMgSO4 · 7H2O
Hβ“˜ MalachiteCu2(CO3)(OH)2
CCarbon
Cβ“˜ AzuriteCu3(CO3)2(OH)2
Cβ“˜ MalachiteCu2(CO3)(OH)2
OOxygen
Oβ“˜ AzuriteCu3(CO3)2(OH)2
Oβ“˜ EpsomiteMgSO4 · 7H2O
Oβ“˜ MalachiteCu2(CO3)(OH)2
MgMagnesium
Mgβ“˜ EpsomiteMgSO4 · 7H2O
SSulfur
Sβ“˜ BorniteCu5FeS4
Sβ“˜ ChalcopyriteCuFeS2
Sβ“˜ ChalcociteCu2S
Sβ“˜ EpsomiteMgSO4 · 7H2O
Sβ“˜ PyriteFeS2
Sβ“˜ SphaleriteZnS
FeIron
Feβ“˜ BorniteCu5FeS4
Feβ“˜ ChalcopyriteCuFeS2
Feβ“˜ PyriteFeS2
CuCopper
Cuβ“˜ AzuriteCu3(CO3)2(OH)2
Cuβ“˜ BorniteCu5FeS4
Cuβ“˜ ChalcopyriteCuFeS2
Cuβ“˜ ChalcociteCu2S
Cuβ“˜ MalachiteCu2(CO3)(OH)2
ZnZinc
Znβ“˜ SphaleriteZnS

Other Databases

Link to USGS MRDS:10109409

Other Regions, Features and Areas containing this locality


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References

 
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