Commodities
PrimaryChromium
TertiaryPlatinum, Palladium, Iridium, Ruthenium, Rhodium
Commodity typeM
Deposit
Model15: Podiform chromite (minor)
Deposit sizeS
WorkingsSurface/Underground
Orebody formPODS, STREAKS, CLOTS, DISCRETE GRAINS, KIDNEY SHAPED BODIES
Ore controlMagmatic Segregation
Materials
Ore mineralsChromite
GangueAntigorite, Picotite, Spinel
Geology
Host rockDunite
Associated rockPeridotite · Coast Range Ophiolite
StructurePrevalent Shearing
Tectonic settingCalifornia Coast Ranges
AlterationDunite Is Serpentinized
Economic & production
Development statusPast Producer
First production1885
Identification
Deposit ID10043681
MRDS IDM100580
Alternate namesSan Juan Mine, Pierce and Benadom Group
RegionNA
Data scoreB
Coordinates35.41803, -120.75459
References
WALKER, G.W., AND GRIGGS, A.B., 1953, GEOLOGICAL INVESTIGATIONS OF CHROMITE IN CALIFORNIA: CALIFORNIA DIVISION OF MINES BULLETIN 134, PT. 2, CH. 2, P. 48, 67.CARLSON, C.A., AND OTHERS, 1985, ANALYSES FOR PLATINUM-GROUP ELEMENTS IN SAMPLES FROM PODIFORM CHROMITE DEPOSITS, CALIFORNIA AND OREGON: U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 85-442, 14 P.STINSON, M.C., 1975, CALIFORNIA DIVISION OF MINES AND GEOLOGY MINERAL PROPERTY REPORT, UNPUB.SMITH, C.T., AND GRIGGS, A.B., 1944, CHROMITE DEPOSITS NEAR SAN LUIS OBISPO, SAN LUIS OBISPO COUNTY, CALIFORNIA: U.S. GEOLOGICAL SURVEY BULLETIN 945-B, P. 36-37.BRADLEY, W.W., HUGUENIN, EMILE, LOGAN, C.A., TUCKER, W.B., AND WARING, C.A., 1918, MANGANESE AND CHROMIUM IN CALIFORNIA: CALIFORNIA STATE MINING BUREAU BULLETIN 76, P. 177-178.ALLEN, J.E., 1941, GEOLOGICAL INVESTIGATION OF THE CHROMITE DEPOSITS OF CALIFORNIA: CALIFORNIA JOURNAL OF MINES AND GEOLOGY V. 37, NO. 1, P. 140.STINSON, 1975