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Long Ledge No. 1

Minor podiform chromite deposit, 24 of 27 in Fresno county (in California)

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

Geologic Information
Other namesWood's, Grizzly Bear
CountryUnited States
State or provinceCalifornia
Geographic location:36°52'30"N, 119°17'44"W
(-119.295556, 36.875)
Geographic context: (click for info)
Deposit typeminor podiform chromite
Model typeMinor Podiform
Deposit formlenses, stringer
Deposit texturenearly massive, nodular, disseminated
Ore typeUnknown
Age of depositLower Ordovician (483±21 Ma Sm-Nd whole rock and mineral)
Age (m.y.)483million years
Area of deposit252sq m
Ore body length84m
Ore body width3m
Mineralogychromite
Host rock typeserpentinized dunite
Host rock length19000
Host rock width13300
Paleotectonic settingmidocean ridge
Ophiolite zonetectonite
Deposits < 10kmpodiform chromite
Rocks within 5kmserpentinized dunite
harzburgite
wehrlite
pyroxenite
gabbro
diorite
schist
metachert
phyllite
quartzite
hornfels
tactite
slate
marble
amphibolite
mica schist
metarhyolite
granitic intrusions
alluvium
Geologic map unit-119.295555555556, 36.875
Nearby scientific dataFind additional scientific data near this location
Economic Information
Tonnage0.0084million metric tons
Ore depth0m
Cr2O3 grade6percent
Rh grade0.009g/t
Ir grade0.05g/t
Ru grade0.15g/t
Pd grade0g/t
Pt grade0.043g/t
Reference information
CommentsOre estimated to a depth of 8 m. Analysis <0.001 ppm Pd. Kings River ophiolite, Hog Mountain, Fresno County.
References
Rynearson, G.A., 1948, Chromite deposits of Tulare and eastern Fresno counties, California, in Geological investigations of chromite in California, Part 3--Sierra Nevada: California Division of Mines Bulletin 134, pt. 3, ch. 3, 104 p.
Matthews, R.A., and Burnett, J.L., 1965, Geologic map of California, Fresno sheet: California Division of Mines and Geology, 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., 1978, Kings River ophiolite, southwest Sierra Nevada foothills, California: Geological Society of America Bulletin, v. 89, p. 617-636.
Shaw, H.F., Chen, J.H., Saleeby, J.B., and Wasserburg, G.J., 1987, Nd-Sr-Pb systematics and age of the Kings River ophiolite, California--Implications for depleted mantle evolution: Contributions to Mineralogy and Petrology, v. 96, p. 281-290.
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