RC East

Prospect, Inactive

Commodities and mineralogy

Main commodities Pb; Zn
Other commodities Ag; As; Au; Cu; Sb
Ore minerals arsenopyrite; galena; pyrite; sphalerite; stibnite
Gangue minerals adularia; carbonate; quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-2
Latitude 63.2826
Longitude -144.6245
Nearby scientific data Find additional scientific data near this location
Location and accuracy The RC East prospect is at an elevation of about 6,000 feet and north of the Kimball Glacier near the center of section 11, T. 19 S., R. 16 E., Fairbanks Meridian. The location is accurate.

Geologic setting

Geologic description

The RC East prospect is the eastern extension of the Rock Candy massive sulfide layer or unit. The prospect consists of massive and semimassive pyrite bands with distinctive sphalerite-galena banding and chalcopyrite along fractures. Hydrothermal quartz-pyrite-arsenopyrite-stibnite veins and veinlets are widely distributed throughout the area (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1979). The average grade of RC East massive sulfide is 0.3 percent copper, 0.9 percent lead, 1.6 percent zinc, 34.2 parts per million silver, and no gold (Lange and others, 1993). The average of 14 surface samples of the veins was 8.48 percent lead, 5.03 percent zinc, 25.43 ounces of silver per ton, 0.62 ounce of gold per ton, 15.75 percent arsenic, and 1.57 percent antimony (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1978).
This occurrence is in the Devonian Jarvis Creek Glacier subterrane (Nokleberg and others, 1992). Rocks at the prospect consist 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in the area are generally parallel to the regional strike, but there are local exceptions (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1976).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 (-144.626743462615, 63.2822160643471)
Mineral deposit model Polymetallic veins and Kuroko massive sulfide (Cox and Singer, 1986; model 22c, model 28a).
Mineral deposit model number 22c, 28a
Age of mineralization Devonian, on the basis of the age of the host rocks, which are in the Jarvis Creek Glacier subterrane (Nokleberg and others, 1992).

Production and reserves

Workings or exploration Two holes were drilled in 1978 on the RC East prospect; they suggest little potential for significant tonnage.
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.



Lange, I. M., Nokleberg, W.J., Newkirk, S. R., Aleinikoff, J.N., Church, S.E., and Krouse, R.H., 1993, Devonian volcanogenic massive sulfide deposits and occurrences, southern Yukon-Tanana terrane, eastern Alaska Range, Alaska: Economic Geology, v. 88, p. 344-376.
Reporters W.T. Ellis (Alaska Earth Sciences), A.S. Wyatt and S.S. Dashevsky (Northern Associates, Inc. ), and W.J. Nokleberg (USGS)
Last report date 3/20/2003