RC

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Ore minerals arsenopyrite; chalcopyrite; 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 63.2865
Longitude -144.6538
Nearby scientific data Find additional scientific data near this location
Location and accuracy The RC occurrence is at an elevation of about 7,000 feet, 3.4 miles north-northwest of Mount Kimball and south of the head of Rock Candy Creek. The occurrence is in the NW1/4NE1/4 section 10, T. 19 S., R. 16 E., Fairbanks Meridian.

Geologic setting

Geologic description

The RC massive sulfide occurrence consists of pyrite bands with distinctive sphalerite-galena banding and chalcopyrite along fractures. The massive sulfide exposures vary from several inches to 5 feet in thickness. Outcrops are limited; extensive boulder trains of massive sulfides extend downslope and along the trend of the outcrop. Hydrothermal quartz-pyrite-arsenopyrite-stibnite veins locally cut blocks of massive sulfide float. Three veins crop out, each as much as 5 inches in thickness. They contain pyrite, arsenopyrite, galena, sphalerite, and stibnite. The gangue is quartz and carbonate with patches of adularia (?) in selvages as much as 2 inches thick. The veins generally crosscut both bedding and schistosity but are locally parallel to them. The average grade of the massive sulfide mineralization is 0.42 percent copper, 3.97 percent lead, 5.51 percent zinc, 57.2 parts per million silver, and traces of gold (Lange and others, 1993). Exploration of the massive sulfide mineralization soon focused on the higher grade polymetallic veins (J.K. Muntzert and others, unpublished Resource Associates of Alaska, Inc. report, 1977).
The rocks in the area consist of a complex sequence of volcaniclastic sedimentary rocks, predominantly of intermediate composition. Felsic and mafic metavolcanic and metasedimentary rocks also occur; they include calcareous schist, dolomite, limestone, siltstone, quartzite, and black carbonaceous schist. The rock units are typically thin bedded, strike northwest, and dip moderately southwest. The schistosity and folds are generally parallel to the regional strike, with local exceptions (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1976).
Geologic map unit (-144.656043203665, 63.286115561773)
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 rock, which is in the Jarvis Creek Glacier subterrane (Nokleberg and others, 1992).

Production and reserves

Workings or exploration Four core holes totaling 1,116 feet were drilled in 1977, 1978, and 1980 on the RC occurrence (S.S. Dashevsky, written communication, 2003). Exploration of the massive sulfide mineralization soon focused on the higher grade polymetallic veins (J.K. Muntzert and others, unpublished Resource Associates of Alaska, Inc. report, 1977).
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

References

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