| Basis for focus area |
Laterite. Based on selection of serpentinite lithologies from ultramafic rocks that include serpentinite in the lithology with Co mineral occurrences in USMIN and MRDS databases. Overlaps with mafic magmatic system Klamath Mountains chromite focus area, which is the source rock for the laterites. |
| Identified resources |
Identified resources and historical production of chromium, cobalt, and nickel. |
| Production |
Nickel and Co produced from the Nickel Mountain laterite. |
| Status |
Exploration in 1970s and 1980s focused on Ni but also identified Co, Cr, and Mn resources (Chamberlain, 1984). Nickel Mountain mine and smelter closed in 1998 due to low Ni prices. |
| Estimated resources |
Pine Flat (1984): Exploration indicated 25 million tons of ore at 0.78% Ni and 0.62% Co (Chamberlain, 1984); Nickel Mountain (1973): In situ resources 907 Mt ore at 1.5% Ni, 0.05% Cr (Vhay and others, 1973). Gasquet laterite (1984): Demonstrated resource of 14.8 million tons of ore at 0.75% Ni (Chamberlain, 1984). Gasquet Mountain and adjacent chromite properties contain Ni-Co-Cr-Mg ore estimated at 29 million tons (Gray and others, 1983). |
| Geologic maps |
Wagner and Gutierrez (2010), scale 1:100,000; Graymer and others (2006), scale 1:275,000; Jennings and others (1977), scale 1:750,000; Gray and others (1983), scale 1:62,500; California Geological Survey Regional Geologic Maps and Geologic Atlas of California, scale 1:250:000. |
| Geophysical data |
Inadequate Rank 3, 4, and 5 aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Chemical weathering of ultramafic rocks, mostly peridotite (Cornwall, 1966). |
| Deposits |
California: Gasquet laterite (MRDS dep_id: 10284620; USMIN Site_ID: CA00071), Pine Flat Mountain (MRDS dep_id: 10211682; USMIN Site_ID: CA00070); Oregon: Nickel Mountain (Hanna mine) (MRDS dep_id: 10067833; USMIN Site_ID: OR00005), Eight Dollar Mountain laterite (MRDS dep_id: 10176940; USMIN Site_ID: OR00002), Woodcock Mountain. |
| Evidence from mineral occurrences |
MRDS; USMIN. |
| Geochemical evidence |
Siskiyou National Forest Land Management Plan; California Geological Survey has an unpublished mineral resource assessment for the Klamath Mountains with soil geochemical data that cites areas of high Ni and Co concentrations. |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
See Jenkins (1954). |
| Comments |
Cobaltite and Co-bearing pentlandite identified at Alta Mine, California (Dunning and Cooper, 2013); Stone Corral (SW of Pine Flat Mountain) is also a potential resource that could be investigated. Nickel Mountain mine and smelter closed in 1998 due to low Ni prices. |
| Cover thickness and description |
Exposed at the surface; the enriched zone occurs >1 ft below the surface. |
| Authors |
Jane M. Hammarstrom, Erica Key, Catherine Wesoloski. |
| New data needs |
Evaluate deposits, detailed geologic mapping (1:24,000 scale and larger), characterize cobalt occurrence. |
| Geologic mapping and modeling needs |
Detailed quadrangle mapping at 1:24,000 or larger. |
| Geophysical survey and modeling needs |
High resolution, Rank 1, aeromagnetic surveys would be useful in delineating serpentinite and other ultramafics. |
| Digital elevation data needs |
Lidar inadequate. |
