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Porter Property

Occurrence in Nevada county in California, United States with commodity Chromium
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Geologic information

Identification information

Deposit ID 10031745
MRDS ID M011167
Record type Site
Current site name Porter Property
Related records 10159692

Geographic coordinates

Geographic coordinates: -121.08187, 39.25489 (WGS84)
Elevation 727
Relative position APPROX. 3 MILES WEST OF NEVADA CITY, CA.
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Geographic areas

Country State County
United States California Nevada

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 016N 008E 16 California

Comments on the location information

  • LOCATED ON THE CREST OF A SMALL SE TRENDING RIDGE.

Commodities

Commodity Importance
Chromium Primary

Materials information

Materials Type of material
Chromite Ore

Alteration

  • (Local) Serpentinization Of Host Rock

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Dunite
    Stratigraphic age (youngest) Late Cretaceous

Nearby scientific data

(1) -121.08187, 39.25489
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Ore body information

  • General form LENSE

Comments on the geologic information

  • THE DEPOSIT OCCURS IN AN ARCUATE ULTRAMAFIC MASS THAT AVERAGES ABOUT 0.5 MILE IN WIDTH AND EXTENDS TO THE NW FOR MORE THAN 5 MILES.

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic
Significant No

Mining district

District name Nevada City - Grass Valley Area

Land status

Ownership category Private

Ownership information

  • Type Operator
    Owner Schmidt, A. J.
    First year 1918
  • Type Owner
    Owner N. G., F. E., And J. L. Wright And J. And J. L. Allen
    Home office Grass Valley, Ca.

Comments on the production information

  • SCHMIDT REPORTED TO THE STATE THAT 1,200 SHORT TONS OF ORE CONTAINING 30 TO 32 PERCENT CR2O3 WERE MINED IN 1918; HIS REPORT TO USGS INDICATED THAT HE SHIPPED 893 LONG TONS OF ORE AND HAD 178 TONS ON HAND AT END OF 1918. IT IS NOT KNOWN IF THE STOCKED ORE WAS SHIPPED AT A LATER DATE.

Comments on the workings information

  • TWO OPEN CUTS, ONE 25 FT. DEEP WITH A SHAFT TO DEPTH OF 40 FT., DRIFT; SHAFT 25 FT. DEEP, SHORT DRIFT.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS M011167

Bibliographic references

  • Deposit

    RYNEARSON, G.A., 1953, CDMG BULL 134, PART 3, CHAPT.5, P. 242.

  • Deposit

    STINSON, M.C., 1976, CDMG MINERAL PROPERTY REPORT, UNPUBLISHED.

General comments

Subject category Comment text
Deposit WORKINGS WERE LOCATED ABOUT 350 FT. APART; ORE IN BOTH WORKINGS APPEARED TO BE ABOUT 4 FT. WIDE. INVESTIGATIONS DID NOT STATE THAT THE TWO ORE BODIES HAD A LINE OF STRIKE COMMON TO BOTH. IF THIS COULD BE PROVED, THE BLOCK OF GROUND BETWEEN THE WORKINGS MIGHT WELL CONTAIN OTHER BODIES OF SIMILAR ORE.
Deposit DEPOSIT CONSISTED OF TWO ORE BODIES: A LARGER ONE WITH A STRIKE OF N59W, DIP OF 85 S, WAS 4FT WIDE AND EXPOSED FOR 35 FT IN 1918. THE SMALLER ORE BODY WAS ALSO 4 FT WIDE.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUN-1973 Gere, W. U.S. Geological Survey
Updater 01-AUG-1982 Oster, Karel L. (Albers, John P.) U.S. Geological Survey