West Bowl

Prospect, Undetermined

Alternative names

Rainy

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pd
Ore minerals bornite; chalcocite; chalcopyrite; covellite; digenite; pyrite pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-4
Latitude 63.3384
Longitude -145.9767
Nearby scientific data Find additional scientific data near this location
Location and accuracy The West Bowl prospect extends between 5,200 to 5,600 feet in elevation in a cirque basin west of the upper North Fork Rainy Creek. The occurrences are centered about 0.4 mile south-southeast of elevation 6045 and about 0.4 miles west-southwest of the center of section 23, T. 18 S., R. 9 E.

Geologic setting

Geologic description

The rocks in the vicinity of the West Bowl prospect are limestone and calcareous sedimentary rocks of the Pennsylvanian and Permian, Slana Spur Formation. It has been intruded by sills or dikes of Triassic mafic and ultramafic rocks, part of the Rainy complex, that varies from gabbro to dunite Rose, 1965; Nokleberg and others, 1992 [MF]; 1992 [Open-File]; Bittenbender and others, 2007).
The prospect was discovered by MAN Resources in 2000 (L.D. Hulbert, oral communication, 2001) but apparently has no workings on it. MAN Resources transferred the property to Nevada Star Resources who held claims on it until at least 2005. Bittenbender and others (2007) of the Bureau of Land Management examined and sampled the prospect in the early 2000s.
The prospect includes two sites of mineralization about a 1,000 feet apart. One is a mineralized skarn inclusion within the mafic-ultramafic complex, and the other is mineralized skarn at the contact of the complex. The skarn has varying proportions of calcite, vesuvianite, garnet, wollastonite, epidote, olivine, and clinopyroxene, and minor plagioclase and actinolite. The ore minerals occur in pods that consist mainly of pyrrhotite, bornite, and chalcopyrite with minor digenite, chalcocite, covellite, and pyrite.
Samples of the skarn collected by MAN Resources within the mafic-ultramafic complex contained up to 4.6 percent copper, 1,040 parts per billion (ppb) gold, 7.7 parts per million (ppm) silver, 52 ppb palladium, and 11 ppb platinum (L.D. Hulbert, oral communication, 2001). Samples of the skarn at the contact of the mafic-ultramafic complex contained up to 2.5 percent copper, 258 ppb gold, 263 ppb palladium, and 55 ppb platinum. Bittenbender and others (2007) collected 6 samples. The highest metal values were 1.21 percent copper, 237 ppb gold, 19.7 ppm silver, and 57 ppb palladium.
Geologic map unit (-145.97896301525, 63.3379825336498)
Mineral deposit model Copper skarn adjacent to and within a mafic-ultramafic complex.
Age of mineralization Source of the mineralization is probably the Triassic mafic-ultramafic complex at the prospect.
Alteration of deposit Limestone adjacent or in a Triassic mafic-ultramafic complex is altered to a mineralized skarn.

Production and reserves

Workings or exploration The prospect was discovered by MAN Resources in 2000 (L.D. Hulbert, oral communication, 2001) but apparently has no workings on it. MAN Resources transferred the property to Nevada Star Resources who held claims on it until at least 2005. Bittenbender and others (2007) of the Bureau of Land Management examined and sampled the prospect in the early 2000s.
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