Unnamed (West Fork Rainy Creek)

Prospect, Undetermined

Commodities and mineralogy

Main commodities Ag; Cu; Ni
Other commodities Zn
Ore minerals chalcopyrite; pyrite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-4
Latitude 63.2938
Longitude -145.9666
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 4,000 feet, about 2.2 miles west-northwest of the junction of the North and West Forks of Rainy Creek. It is 0.3 mile southeast of the center of section 2, T. 19 S., R. 9 E.

Geologic setting

Geologic description

The rocks in the area are tuffs and sediments that are interbedded with Triassic mafic and ultramafic rocks (Rose, 1965; Nokleberg and others, 1992 [MF], 992 [Open-File]). Bittenbender and others (2007) found an iron-stained outcrop of gabbro about 10 by 20 feet in size with pyrrhotite, pyrite, and chalcopyrite. Samples contained up to 7,040 parts per million (ppm) copper, 1,720 ppm nickel, 2.9 ppm silver, and 258 ppm zinc; most samples contained about a 10th as much. They identified a 30 by 50 foot xenolith nearby of garnet-epidote skarn in gabbro as well as several smaller such bodies. The skarn has a few percent disseminated chalcopyrite. They ascribe the source of the mineralization and the skarns to Triassic(?) gabbro intrusions nearby.
Geologic map unit (-145.968858685173, 63.2933812559467)
Mineral deposit model Copper-nickel mineralization in skarn and gabbro.
Age of mineralization Mineralization possibly related to Triassic(?) gabbro.
Alteration of deposit Mineralized skarn developed near gabbro intrusions.

Production and reserves

Workings or exploration Examined and sampled by Bureau of Management 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