The Porter Property is a chromium mine located in Nevada county, California at an elevation of 2,385 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.
Elevation: 2,385 Feet (727 Meters)
Primary Mineral: Chromium
Lat, Long: 39.255, -121.08083
Map: View on Google Maps
Porter Property MRDS details
Primary: Porter Property
District: Nevada City - Grass Valley Area
Land ownership: Private
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 indicate a claim status and does not necessarily indicate an area is open to prospecting.
Owner Name: N. G., F. E., And J. L. Wright And J. And J. L. Allen
Home Office: Grass Valley, Ca.
Owner Name: Schmidt, A. J.
Years: 1918 -
Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
General Physiographic Area: Pacific Mountain System
Physiographic Province: Cascade-Sierra Mountains
Physiographic Section: Sierra Nevada
Mineral Deposit Model
Alteration Type: L
Alteration Text: Serpentinization Of Host Rock
Age Type: Host Rock
Age Young: Late Cretaceous
Comment (Production): 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.
Comment (Workings): TWO OPEN CUTS, ONE 25 FT. DEEP WITH A SHAFT TO DEPTH OF 40 FT., DRIFT; SHAFT 25 FT. DEEP, SHORT DRIFT.
Comment (Geology): 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.
Comment (Location): LOCATED ON THE CREST OF A SMALL SE TRENDING RIDGE.
Comment (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.
Comment (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.
Reference (Deposit): RYNEARSON, G.A., 1953, CDMG BULL 134, PART 3, CHAPT.5, P. 242.
Reference (Deposit): STINSON, M.C., 1976, CDMG MINERAL PROPERTY REPORT, UNPUBLISHED.