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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
Mineralogychromite
Host rock typeserpentine
Host rock length52000
Host rock width2000
Ophiolite zonetectonite
Deposits < 10kmpodiform chromite
Rocks within 5kmserpentine
dunite
basalt flow
basalt tuff
slate
graywacke
conglomerate
mudstone
quartzite
chert
gabbro
greenstone
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.
References
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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