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  3. Mineral Resource Data System (MRDS)

La Primera

Past Producer in San Luis Obispo county in California, United States with commodity Chromium
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Nearby scientific data
  9. Ore body information
  10. Economic information about the deposit and operations
  11. Mining district
  12. Mineral rights holdings
  13. Land status
  14. Ownership information
  15. Production statistics
  16. Links to other databases
  17. Bibliographic references
  18. General comments
  19. Reporter information

Geologic information

Identification information

Deposit ID 10286703
MRDS ID M100576
MAS/MILS ID 0060790030
Record type Site
Current site name La Primera
Alternate or previous names La Primero, Hardface, El Primero
Related records 10103912

Geographic coordinates

Point of reference Trench
Geographic coordinates: -120.68767, 35.35967 (WGS84)
Elevation 541
Location accuracy 250(meters)

Site location context

Political divisions (FIPS codes)

San Luis Obispo(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

San Luis Obispo(quadrangle 1:24,000 scale)

San Luis Obispo(quadrangle 1:100,000 scale)

San Luis Obispo(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Central Coastal(hydrologic unit)

Central California Coastal(hydrologic accounting unit)

Central California Coastal(hydrologic subregion)

California(hydrologic region)

Federal lands

ST(Federal land areas administered by ST)

Geographic areas

Country State County
United States California San Luis Obispo

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 029 S 012 E 33 NESE California

Commodities

Commodity Importance
Chromium Critical Primary

Materials information

Materials Type of material
Chromite Unknown
Olivine Unknown
Pyroxene Unknown
Serpentine Unknown
Uvarovite Unknown

Nearby scientific data

Trench (1) -120.68767, 35.35967
ListMap

Economic information

Ore body information

  • Strike N37E
    Dip 10N
    Thickness 1M
    Length 50M
    Width 30M
    Area 3HA
    Depth to top 0M
    Field Value
    Type of Orebody #1 DISSEMINATED
    Shape of Orebody #1 TABULAR
    Primary mode of Origin MAGMATIC DIFFER
    Primary Ore Control LITHOLOGY
    Degree of Wallrock Alter. INTENSE
    Type of Wallrock Alter. #1 CARBONITIZATION
    Strike And Dip N37E:10N
    Minimum Depth to Top 0
    Avg. Thick. Unconsol. Mat. 0
    Min. Thick. Unconsol. Mat. 0
    Total Surface Area (HA) 3
    Date of Last Modification 830316

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant No
Discovery year 1890
Year of first production 1890

Mining district

District name Cuesta Pass

Mineral rights holdings

Type of mineral rights Minerals Only

Land status

Ownership category Federal

Ownership information

  • Type Operator
    Owner Pierce Brothers
    Home office California
    Year 1958
  • Type Owner
    Owner Swartz, Arthur
    Interest 100
    Home office California
    Year 1976

Production statistics

  • Year 1880
    Description Lump Ore Mined 250 Mt
  • Year 1918
    Description Lump Ore Mined 25 Mt
  • Year 1952
    Description Lump Ore Mined From 1952-1958 280 Mt @ 44.6 Pct-2.6:1 Cr:Fe
  • Year 1952
    Description Concentrates Produced From 1952-1958 11400 Mt @ 45.8 Pct-2.3:1 Cr:Fe
  • Year 1952
    Description Ore Mined From 1952-1958 37400 Mt

Comments on the reserve resource information

  • MAT 1 COL 1 REPRESENTS AVERAGE ORE GRADE MAT 1 COL 2 REPRESENTS HIGH GRADE ORE MAT 1 COL 3 REPRESENTS LOW GRADE ORE

Reference information

Bibliographic references

  • Deposit

    CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD, CENTRAL

  • Deposit

    COAST REGION. SURFACE WATER DEGRADATION BY INACTIVE

  • Deposit

    METAL MINES IN NORTHWEST SAN LUIS OBISPO COUNTY, CA,

  • Deposit

    DECEMBER 1993 (P. 6-8).

  • Deposit

    CALIF. STATE MINING BUR. BULLETIN 76, 1918, P. 171.

  • Deposit

    CALIF. DIV. MINES BULLETIN 134, 1953, PART II, CHAPT. 2,

  • Deposit

    P. 61-63.

General comments

Subject category Comment text
Deposit 325 TONS WAS SHIPPED PRIOR TO 1918.1952-1958 37,390 LT MILLI MINED,11397 LT.CONCENTRATES PRODUCED. 282 LT.LUMP ORE MINED. ORG RAN 44.6% CR2O3,11.5% FE,CR/FE=2.6.CONCENTRATE RAN 45.8% 13.2 PERCENT CR2O3,CR/FE=2.3. RE-SERVE ESTIMATE-50%=5 FOOT P ION OF EXPOSED ORE,25%=10 FOOT,10%=25 FOOT INADEQUATE RESOURCES FOR COST ANALYSIS. ANALYSIS BY CDMG IN 1976 GAVE FOLLOWING PERCENTAGES-MASSIVE 2 01.57,CR2O3 54.08,FEO 10.37,TOTAL FE 14.15,AL203 14.17,MGO CR/FE 3.36.DISSEMINATE ORE=SI02 14.23,CR2O3 33.62,FEO 09.59 FE 16.72,AL203 13.27,MGO 18.82,CR/FE 1.77.

Reporter information

Type Date Name Affiliation Comment
Reporter 05-DEC-94 Wetzel, Nicholas U.S. Bureau of Mines

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

External references

Maps centered on this site

Authoritative California resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.