Richards Mine [2] (Annex Chrome Mine; Rough and Ready Mine [1918]), Peoria Flat, Yosemite Junction, Tuolumne County, California, USAi
Regional Level Types | |
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Richards Mine [2] (Annex Chrome Mine; Rough and Ready Mine [1918]) | Mine |
Peoria Flat | Flat |
Yosemite Junction | - not defined - |
Tuolumne County | County |
California | State |
USA | Country |
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Latitude & Longitude (WGS84):
37° 54' 30'' North , 120° 29' 29'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
Place | Population | Distance |
---|---|---|
Chinese Camp | 126 (2011) | 6.6km |
Jamestown | 3,433 (2011) | 7.8km |
Tuttletown | 668 (2011) | 9.7km |
Sonora | 4,818 (2017) | 12.8km |
East Sonora | 2,266 (2011) | 13.8km |
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 | 18km |
Mindat Locality ID:
98145
Long-form identifier:
mindat:1:2:98145:2
GUID (UUID V4):
15059469-e915-4cbf-8e19-92746036077e
A former Cr-Au mine located in sec. 25 & 36, T1N, R13E, and in secs. 30 & 31, T1N, R14E, MDM, 0.7 km (2,400 feet) NE of Peoria Flat (coordinates of record), on private land (fee ownership). Discovered in 1916. Claims cover 209.6 acres. First production occurred in 1918. Owned by Otis Rosasco, Jamestown, California 95327. Operated by the Bradley Mining Co. (1942). MRDS database stated accuracy for this location is 10 meters. The claim map in Pl. 8, Logan (1949) shows location only in secs. 30 & 31, T1N, R14E, but does include the acreage reported in previous reports.
Mineralization is hosted in the Amador rock unit (Late Jurassic-Late Permian dunite). The ore body is lenticular, strikes N60-70W and dips SW at a width of 1.83 meters. Local alteration involved the serpentinization and silicification of host rock. Ore exposed in pit in zone 6 feet wide and strikes N60W. Exposed ore is in highly weathered serpentinite. The deposit occurs in the northern part of the westernmost of 2 serpentine belts which trend NW-SE across the county. The belt is exposed over an area 30 km by 6 km. Local rocks include ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains).
Local structures include shearing in host rock which is strongly developed in a N65-75W direction; and the Bear Mountain Fault zone trending NW.
Workings include surface and underground openings comprised of an open cut 180 feet long, 20 to 30 feet wide and 10 to 20 feet deep, trending N60W, plus 2 short adits driven N10E and S60E, and several shallow prospect trenches (1975). The ore zone was exposed in the floor and N wall of the main pit.
Ore shipped during WWI assayed as high-grade.
Assay analysis results: Year: 1918: ^36.7% Cr2O3 (37 weight percent).
Indicated ore reserves were 7,700 tons. Dump contains ore mixed with waste and may yield 40 tons of ore.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
ⓘ Formula: Fe2+Cr3+2O4 |
ⓘ Magnesiochromite Formula: MgCr2O4 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 4 - Oxides and Hydroxides | |||
---|---|---|---|
ⓘ | Chromite ? | 4.BB.05 | Fe2+Cr3+2O4 |
ⓘ | Magnesiochromite | 4.BB.05 | MgCr2O4 |
List of minerals for each chemical element
O | Oxygen | |
---|---|---|
O | ⓘ Chromite | Fe2+Cr23+O4 |
O | ⓘ Magnesiochromite | MgCr2O4 |
Mg | Magnesium | |
Mg | ⓘ Magnesiochromite | MgCr2O4 |
Cr | Chromium | |
Cr | ⓘ Chromite | Fe2+Cr23+O4 |
Cr | ⓘ Magnesiochromite | MgCr2O4 |
Fe | Iron | |
Fe | ⓘ Chromite | Fe2+Cr23+O4 |
Other Databases
Link to USGS MRDS: | 10043707 |
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