Foley

Prospects, Active?

Commodities and mineralogy

Main commodities Cu; Ni; Pd; Pt
Other commodities Au; Co; Cr; Ir; Rh; Ru
Ore minerals chalcopyrite; chromite; cobaltite; magnetite; malachite; pentlandite; pyrite; pyrrhotite; safflorite
Gangue minerals garnet; olivine; pyroxene; serpentine

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-4
Latitude 63.3179
Longitude -145.9238
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Foley prospect includes several prospects centered at an elevation of about 4,300 feet about 2.1 miles north-northwest of the junction of the North and West Forks of Rainy Creek It is near the northeast corner of section 36, T. 18 S., R. 9 E.

Geologic setting

Geologic description

These prospect consist of: 1) several sulfide-bearing, garnet-pyroxene skarns in carbonate beds intruded by the Rainy ultramafic-mafic complex, and 2) sulfide-bearing basalt, diorite, gabbro, and serpentinite in the complex (Foley, 1992). The Rainy complex intrudes the Slana Spur Formation of Pennsylvanian and Permian age; the Formation includes some some carbonate layers. The Rainy complex is up to 5,000 feet thick, dips shallowly north, and can be traced for more than 15 miles; it is mainly serpentinized dunite with subordinate peridotite, pyroxenite, and gabbro (Nokleberg and others, 1992; Nokleberg and others, 1992; Bittenbender and others, 2007). The base of the complex is a layered gabbro as much as 1,500 feet thick.
The prospects were found by industry in the 1990s; examined and sampled by the Bureau Mines (Foley, 1992), the U.S. Geological Survey (Nokleberg and others, 1991), and the Bureau of Land Management (Bittenbender and others, 2007).
The mineralization examined by Nokleberg and others (1991) consists of disseminated and nearly massive pods of pyrite, pyrrhotite, magnetite, and chalcopyrite with trace pentlandite, cobaltite, and safflorite, in chromite-bearing olivine cumulates. A sample contained more than 5,000 parts per million (ppm) chromium. A U.S. Bureau of Mines sample of gabbronorite rubble contained 0.9 percent nickel, 0.25 percent copper, 0.02 percent cobalt, 1,070 parts per billion (ppb) palladium, 725 ppb platinum, 300 ppb iridium, 70 ppb rhodium, and 60 ppb ruthenium. Massive sulfide float contains 0.41 percent copper, 0.09 percent cobalt, and 65 ppb palladium (Foley, 1992). Mineralized skarn samples taken near the contact of the Rainy complex contain as much as 6.2 ppm silver, 85 ppb gold, 0.05 percent cobalt, 2.0 percent copper, and 0.09 percent nickel. The area was examined by Bittenbender and others (2007) but they did not locate the prospects.
Geologic map unit (-145.926059122787, 63.3174829234633)
Mineral deposit model Nickel-copper-PGE mineralization in a differentiated mafic-ultramafic complex; disseminated chromite in a layered mafic-ultramafic complex; Cu skarn (Cox and Singer, 1986; model 18b).
Mineral deposit model number 18b
Age of mineralization Genetically related to the emplacement of a Late Triassic mafic-ultramafic complex.

Production and reserves

Workings or exploration Found by industry in the 1990s. Examined and sampled by the Bureau Mines (Foley, 1992), the U.S. Geological Survey (Nokleberg and others, 1991), and the Bureau of Land Management (Bittenbender and others, 2007).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Bittenbender, P.E., Bean, K.W., Kurtak, J.M., and Deininger, James Jr., 2007, Mineral assessment of the Delta River Mining District area, east-central, Alaska: U.S. Bureau of Land Management, Alaska Technical Report 57, 675 p.
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