West Crash

Prospect, Active

Commodities and mineralogy

Main commodities Cu; Ni; Pd; Pt
Other commodities Au; Cr
Ore minerals chalcopyrite; garnierite; magnetite; malachite; pentlandite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.313
Longitude -146.2392
Nearby scientific data Find additional scientific data near this location
Location and accuracy The West Crash prospect is at an elevation of about 5,330 feet, about 4.6 miles northwest of the junction of Eureka Creek and Broxson Gulch. It is about 0.6 mile west-northwest of the center of section 33, T. 18 S., R. 8 E. The location is accurate.

Geologic setting

Geologic description

The West Crash prospect is in an east-trending, northward-dipping sill of Late Triassic, ultramafic and mafic rocks that are part of the Eureka complex (Rose, 1966; Nokleberg and others, 1992 [MF]; Nokleberg and others, 1992 [Open-File]. The sill is about 100 feet thick at this prospect; it dips north about 40 degrees, and consists of differentiated pyroxenite and gabbro. The footwall of the sill is siliceous volcanic rocks; the hanging wall is argillite, slate, and graywacke. The rocks are locally iron-stained and altered with plagioclase going to saussurite and pyroxene going to actinolite. Malachite and garnierite staining is locally prominent.
The West Crash prospect was found by industry in the 1990s. It was examined and sampled by the Bureau of Land Management in about 2003. Bittenbender and others (2007 ) collected four samples. Two samples of gossanous material contained up to 37 parts per billion (ppb) gold, 399 parts per million (ppm) chromium, 872 ppm copper, 4,020 ppm nickel, 118 ppb platinum, and 168 ppb palladium. The other two did not have any notable metals.
Geologic map unit (-146.241464561109, 63.3125772088919)
Mineral deposit model Nickel-copper-PGE mineralization in a differentiated mafic-ultramafic sill.
Age of mineralization Genetically related to the emplacement of a Late Triassic mafic-ultramafic complex.
Alteration of deposit The ultramafic rocks rock units are moderately to strongly serpentinized. The rocks are locally iron-stained and altered with plagioclase going to saussurite and pyroxene going to actinolite. Malachite and garnierite staining is locally prominent.

Production and reserves

Workings or exploration Found by industry in the 1990s. Examined and sampled by the Bureau of Land Management in about 2003.
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS); D.J. Grybeck (Contractor, USGS)
Last report date 5/13/2012