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Long Ledge No. 2

Minor podiform chromite deposit, 25 of 27 in Fresno county (in California)

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

Geologic Information
Other namesPearson, Riverview
CountryUnited States
State or provinceCalifornia
Geographic location:36°52'25"N, 119°17'40"W
(-119.294444, 36.873611)
Geographic context: (click for info)
Deposit typeminor podiform chromite
Model typeMinor Podiform
Deposit formsmall lenses
Deposit texturenearly massive
Ore typeUnknown
Age of depositLower Ordovician (483±21 Ma Sm-Nd whole rock and mineral)
Age (m.y.)483million years
Mineralogychromite
Host rock typeserpentinized dunite
Host rock length19000
Host rock width13300
Paleotectonic settingmidocean ridge
Ophiolite zonetectonite
Deposits < 10kmpodiform chromite
Rocks within 5kmserpentinized dunite
biotite granite dikes
harzburgite
wehrlite
pyroxenite
gabbro
diorite
schist
metachert
phyllite
quartzite
hornfels
tactite
slate
marble
amphibolite
mica schist
metarhyolite
granitic intrusions
alluvium
Geologic map unit-119.294444444444, 36.8736111111111
Nearby scientific dataFind additional scientific data near this location
Economic Information
Discovery date1917
Startup date1917
Tonnage6.1e-05million metric tons
Mine depth10.6m
Ore depth0m
Cr2O3 grade40percent
Reference information
CommentsProduction of 3 carloads is based on 20 t per carload. 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.
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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