RC West

Occurrence, Probably inactive

Commodities and mineralogy

Main commodities Pb; Zn
Other commodities Ag; Cu
Ore minerals chalcopyrite; galena; pyrite; sphalerite
Gangue minerals chlorite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-2
Latitude 63.2953
Longitude -144.692
Nearby scientific data Find additional scientific data near this location
Location and accuracy The RC West occurrence is one-half mile long, exposed on the north side of the ridge 3.8 miles north-northwest of Mount Kimball. The occurrence is at the point on the ridge where the mineralized rock crosses it. The occurrence is about 0.2 mile south of the center of section 4, T. 19 S., R. 16 E., Fairbanks Meridian. The location is accurate.

Geologic setting

Geologic description

The RC West occurrence consists of multiple bands and lenses of pyrite-rich sulfides in a sequence of quartz-chlorite-sericite schist, quartz-sericite schist, dolomite, calcareous schist, limestone, and black carbonaceous schist. For about 100 feet, pyrite, galena, sphalerite, and minor chalcopyrite occur as multiple bands and disseminations as much as 6 inches thick over a total thickness of 8 to 10 feet. Three grab samples contained 0.08 to 0.71 percent copper, 0.81 to 5.8 percent lead, 1.4 to 10.6 percent zinc, 2.04 to 21.2 ounces of silver per ton, and less than 0.003 ounce of gold per ton (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1976).
This occurrence is in the Jarvis Creek Glacier subterrane of Devonian age (Nokleberg and others, 1992). It consists of a complex sequence of volcaniclastic sedimentary rocks, predominantly of intermediate composition. The unit includes felsic and mafic metavolcanic and metasedimentary rocks, including calcareous schist, dolomite, limestone, siltstone, quartzite, and black carbonaceous schist. The rocks are typically thin bedded, strike northwest, and dip moderately southwest. The schistosity and folds in the area are generally parallel to the regional strike, but there are local exceptions (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1976).
Geologic map unit (-144.694243225062, 63.2949151127013)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization Devonian, on the basis of the age of the host rock, which is in the Jarvis Creek Glacier subterrane (Nokleberg and others, 1992).

Production and reserves

Workings or exploration The only exploration work has been surface sampling and prospecting.
Indication of production None

Additional comments

Unpublished data cited is available for viewing by contacting Grayd Resources Inc. in Vancouver, B. C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.

References