Holbrook and McGuire Mine (Low Grade workings; High Grade workings; Holbrook and McGuire group), Mountain Top, French Creek Mining District, Calaveras County, California, USAi
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Latitude & Longitude (WGS84):
37° 57' 37'' North , 120° 33' 47'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
Place | Population | Distance |
---|---|---|
Copperopolis | 3,671 (2011) | 7.3km |
Tuttletown | 668 (2011) | 9.7km |
Angels Camp | 2,677 (2012) | 12.2km |
Jamestown | 3,433 (2011) | 12.3km |
Chinese Camp | 126 (2011) | 15.1km |
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
Local clubs are the best way to get access to collecting localities
Club | Location | Distance |
---|---|---|
Calaveras Gem & Mineral Society | Angels Camp, California | 12km |
Mindat Locality ID:
75365
Long-form identifier:
mindat:1:2:75365:5
GUID (UUID V4):
00fb3935-58be-4413-ae6e-2a420391515b
A former Cr-Fe mine located in sec. 8, T1N, R13E, MDM, 1.0 km (0.6 mile) E of Mountain Top (summit), along Bean Gulch, on Bureau of Land Management administered land. Discovered in 1890. First operated in 1918. Owned by Allan Dunbar (last operator), California (1942-1976). MRDS database stated accuracy for this location is 10 meters.
The ore body strikes N50W and dips 80E at a width of 2 meters and a length of 45 meters. Ore body No. 1 is disseminated and ore body No. 2 is lenticular. The primary mode of origin was magmatic differentiation. Primary ore control was lithology while the second control was faulting. Wallrock alteration is intense (carbonitization). Local rocks include ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains).
Workings include surface and underground openings.
Production to 1918 was 600 tons of ore at 40 to 48% Cr2O3, plus 250 tons after 1918.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
ⓘ Magnesiochromite Formula: MgCr2O4 |
ⓘ Magnesite Formula: MgCO3 |
ⓘ 'Serpentine Subgroup' Formula: D3[Si2O5](OH)4 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 4 - Oxides and Hydroxides | |||
---|---|---|---|
ⓘ | Magnesiochromite | 4.BB.05 | MgCr2O4 |
Group 5 - Nitrates and Carbonates | |||
ⓘ | Magnesite | 5.AB.05 | MgCO3 |
Unclassified | |||
ⓘ | 'Serpentine Subgroup' | - | D3[Si2O5](OH)4 |
List of minerals for each chemical element
H | Hydrogen | |
---|---|---|
H | ⓘ Serpentine Subgroup | D3[Si2O5](OH)4 |
C | Carbon | |
C | ⓘ Magnesite | MgCO3 |
O | Oxygen | |
O | ⓘ Magnesite | MgCO3 |
O | ⓘ Magnesiochromite | MgCr2O4 |
O | ⓘ Serpentine Subgroup | D3[Si2O5](OH)4 |
Mg | Magnesium | |
Mg | ⓘ Magnesite | MgCO3 |
Mg | ⓘ Magnesiochromite | MgCr2O4 |
Si | Silicon | |
Si | ⓘ Serpentine Subgroup | D3[Si2O5](OH)4 |
Cr | Chromium | |
Cr | ⓘ Magnesiochromite | MgCr2O4 |
Other Databases
Link to USGS MRDS: | 10187077 |
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Other Regions, Features and Areas containing this locality
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References
(n.d.) Minerals Availability System (MAS), U.S. Bureau of Mines.file ID #0060090560