Clary & Langford Mine (Porter and Springs Mine; Nassau), Carmen City, Foothill Copper Belt, Calaveras Co., California, USA
|Latitude & Longitude (WGS84):||38° 2' 30'' North , 120° 38' 48'' West|
|Latitude & Longitude (decimal):||38.04167,-120.64667|
|Köppen climate type:||Csa : Hot-summer Mediterranean climate|
A former Cr-Fe mine located in sec. 9 & in the NW¼ sec. 10, T2N, R12E, MDM, 3.9 km (2.4 miles) E of Carmen City and 5 miles N of Copperopolis (about 150 feet E of the Copperopolis-Angels Camp Road at a point about 0.6 mile N of Milton Road junction, on private land. Discovered and first operated in 1900. Owned by C. J. Tiscornia Ranches, Inc., San Andreas, California 95429. Operated by J. E. Porter, J. H. Spring (1918). Active prior to World War I until 1918. MRDS database stated accuracy for this location is 10 meters.
Mineralization is a lens of massive chromite in serpentine. The ore body strikes N40W and dips 90N at a thickness of 1 meter, width of 15 meters and a length of 20 meters, over an area of 1 HA. It is tabular, disseminated. A second ore body is irregular. The primary mode of origin was magmatic differentiation. Primary ore control was lithology. Wallrock alteration is intense (carbonitization). The ore is highly sheared serpentine. No ore can be seen in place but a few fragments of medium- to coarse-grained, massive chromite containing minor quantities of kammererite are scattered about the dumps. Local rocks include Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains).
Workings include surface and underground openings. Developed by two 50 foot deep shafts as well as an open cut (all now flooded). A shaft and a few open cuts were reported in a small, detached mass of serpentine ½ mile to the W (NE¼ sec. 9).
Production information: A total of 348 long tons of ore were mined. Reserves probably negligible. Some of the ore mined was used by a local copper smelter as furnace linings.
Analytical data results: The ore contained 45-46% Cr2O3.
Analysis by the California Division of Mines and Geology in 1976 gave the following percentages: Cr2O3: 46.60; FeO: 8.31; total Fe: 12.87; Al2O3: 12.99; MgO; Cr:Fe = 3.19:1.
2 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
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145 - 201.3 Ma
|Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains)|
Age: Jurassic (145 - 201.3 Ma)
Stratigraphic Name: Copper Hill Volcanics; Gopher Ridge Volcanics; Logtown Ridge Formation; Mariposa Formation; Monte de Oro Formation; Oregon City Formation; Peaslee Creek Volcanics; Penon Blanco Formation; Brower Creek Volcanic Member; Smartville Complex
Description: Undivided Mesozoic volcanic and metavolcanic rocks. Andesite and rhyolite flow rocks, greenstone, volcanic breccia and other pyroclastic rocks; in part strongly metamorphosed. Includes volcanic rocks of Franciscan Complex: basaltic pillow lava, diabase, greenstone, and minor pyroclastic rocks.
Comments: Western Sierra Nevada and western Klamath Mountains. Mostly basaltic to andesitic breccias, flows, and tuffs, metamorphosed but with primary volcanic features generally recognizable. Minor associated sandstone and conglomerate. Largely or entirely of marine origin. Includes some rocks interpreted as ophiolites (Smartville complex)
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.