Sweetwater Mine

The Sweetwater Mine is a chromium mine located in San Luis Obispo county, California at an elevation of 1,549 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.

Site Name

Primary: Sweetwater Mine
Secondary: San Juan Mine
Secondary: Pierce and Benadom Group

Commodity

Primary: Chromium
Tertiary: Platinum
Tertiary: Palladium
Tertiary: Iridium
Tertiary: Ruthenium
Tertiary: Rhodium

Location

State: California
County: San Luis Obispo

Land Status

Land ownership: National Forest
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

Holdings

Not available

Workings

Type: Surface/Underground

Ownership

Owner Name: Pierce, W. W.
Years: 1953 -

Owner Name: Ruda And Negranti, J. D. Hoffman, Harry Stevens
Years: 1957 -

Production

Year: 1950
Time Period: 1880-1950
Material type: ORE
Description: Cp_Grade: ^46% Cr2o3

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1885
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

General Physiographic Area: Pacific Mountain System
Physiographic Province: Pacific Border Province
Physiographic Section: California Coast Ranges

Mineral Deposit Model

Model Name: Podiform chromite (minor)

Orebody

Form: PODS, STREAKS, CLOTS, DISCRETE GRAINS, KIDNEY SHAPED BODIES

Structure

Type: L
Description: Prevalent Shearing

Alterations

Alteration Type: L
Alteration Text: Dunite Is Serpentinized

Rocks

Name: Peridotite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Late Jurassic

Name: Peridotite
Role: Associated
Age Type: Associated Rock
Age Young: Late Jurassic

Name: Peridotite
Role: Associated
Age Type: Host Rock
Age Young: Late Jurassic

Analytical Data

Analytical Data: RH=8, 2 PPB. AVE CR:FE=2.61:1. CRUDE ORE AVE 35% CR2O3, CONCENTRATES AVE 52% CR2O3.
Analytical Data: RU=400, <100 PPB
Analytical Data: IR=170, 50 PPB
Analytical Data: PD=2, 2 PPB
Analytical Data: 2 PGE ANALYSES: PT=10, 10 PPB

Materials

Ore: Chromite
Gangue: Picotite
Gangue: Spinel
Gangue: Antigorite

Comments

Comment (Deposit): LARGEST DEPOSIT IN GROUP. THERE ARE 600 FT OF CHROME OUTCROPS OVER A VERTICAL RANGE OF 150 FT. FORMED BY SEVERAL SEPARATE ORE BODIES

Comment (Location): IN LOS PADRES NATIONAL FOREST. ON SOUTHWEST SLOPE OF SANTA LUCIA RANGE. UTM PLACED ON LOWEST PART OF OPEN PIT. MINE IS ON AND E-W SPUR NEAR WEST END OF CUESTA RIDGE. LOCATION IS SHOWN AS MINE SYMBOL ON TOPO MAP

Comment (Development): USBM EVALUATED MINE AND ASSAYED 162 SAMPLES IN 1941

Comment (Deposit): RECORD W025008 HAS BEEN MERGED AND DELETED.

Comment (Workings): 5 OPEN PITS OVER 325 FT DISTANCE, RUNNING N60W; 5 TUNNELS AND CROSSCUTS USED UNTIL THE 1950'S

References

Reference (Deposit): STINSON, M.C., 1975, CALIFORNIA DIVISION OF MINES AND GEOLOGY MINERAL PROPERTY REPORT, UNPUB.

Reference (Deposit): 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.

Reference (Production): STINSON, 1975

Reference (Deposit): ALLEN, J.E., 1941, GEOLOGICAL INVESTIGATION OF THE CHROMITE DEPOSITS OF CALIFORNIA: CALIFORNIA JOURNAL OF MINES AND GEOLOGY V. 37, NO. 1, P. 140.

Reference (Deposit): 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.

Reference (Deposit): 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.

Reference (Deposit): 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.

California Gold

"Where to Find Gold in California" looks at the density of modern placer mining claims along with historical gold mining locations and mining district descriptions to determine areas of high gold discovery potential in California. Read more: Where to Find Gold in California.