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Courtwright Property

Minor podiform chromite deposit, 2 of 5 in Amador county (in California)

Sections of this page: [Geologic] - [Economic] - [Reference]

Geologic Information
Other namesDaggett Lease, Woods and Roach Lease
CountryUnited States
State or provinceCalifornia
Geographic location:38°19'41"N, 120°51'47"W
(-120.863056, 38.328056)
Geographic context: (click for info)
Deposit typeminor podiform chromite
Model typeMinor Podiform
Deposit formsmall lenses, stringer
Deposit texturemedium-grained massive
Ore typeUnknown
Age of depositPermian (280±3 m.y. 206Pb/238U, 282±3 m.y. 207Pb/235U)
Age (m.y.)281million years
Host rock typeserpentine
Host rock length52000
Host rock width2000
Ophiolite zonetectonite
Deposits < 10kmpodiform chromite
Rocks within 5kmserpentine
basalt flow
basalt tuff
andesite flow
andesite tuff
andesite breccia
rhyolite flow
rhyolite tuff
Geologic map unit-120.863055555556, 38.3280555555556
Nearby scientific dataFind additional scientific data near this location
Economic Information
Discovery date1916
Startup date1916
Tonnage9.5e-05million metric tons
Mine depth9.8m
Ore depth0m
Cr2O3 grade39percent
Rh grade0.008g/t
Ir grade0.14g/t
Ru grade0.24g/t
Pt grade0.019g/t
Si2O2 %4percent
Reference information
CommentsPd <0.001 ppm. Bear Mountain ophiolitic melange. Amador County.
Cater, F.W., Jr., 1948, Chromite deposits of Calaveras and Amador counties, California, in Geological investigations of chromite in California, Part 3--Sierra Nevada: California Division of Mines Bulletin 134, pt. 3, ch. 2, 60 p.
Wagner, D.L., Jennings, C.W., Bedrossian, T.L., and Bortugno, E.J., 1981, Geologic map of the Sacramento quadrangle: California Division of Mines and Geology Regional Geologic Map Series Map no. 1A, scale 1:250,000.
Carlson, C.A., Wilson, S.A., Carlson, R.R., Bradley, L., Cornell, J., Gent, C., Gass, W., Groeneboer, H., Haffty, J., Haubert, A., Love, A., McDade, J.M., Moore, R., Riley, L., Moring, B.C., Singer, D.A., and Page, N. J, 1985, Analyses for platinum group elements in samples from podiform chromite deposits, California and Oregon: U.S. Geological Survey Open-File Report 85-442, 15 p.
Saleeby, J.B., 1982, Polygenetic ophiolite belt of the California Sierra Nevada--Geochronological and tectonostratigraphic development: Journal of Geophysical Research, v. 87, no. B3, p. 1803-1824.
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