Pyrola

Prospect, Active

Commodities and mineralogy

Main commodities Ag; As; Au; Cu; Pb; Zn
Ore minerals boulangerite; chalcopyrite; galena; jamesonite; pyrite; sphalerite
Gangue minerals barite

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale D-2
Latitude 57.9629
Longitude -134.554
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Pyrola prospect is at an elevation of about 2,600 feet, about 0.2 mile north-northeast of the southwest corner of sec. 15, T. 45 S., R. 67 E. The prospect is MAS no. 0021140184 (U.S. Bureau of Land Management, 2002). The location is accurate with 0.2 mile.

Geologic setting

Geologic description

The Pyrola prospect is a volcanogenic massive-sulfide deposit in Triassic(?) felsic to intermediate volcanic rocks, carbonaceous siltstone, argillite, limestone and dolomite (Van Nieuwenhuyse, 1984; Berg, 1984; Newberry and others, 1997). The deposit consists of a 9-meter-thick stratiform layer of massive sulfides with barite and massive barite, interbedded with black argillite. The sulfides are mainly pyrite, sphalerite, and galena with minor chalcopyrite, jamesonite, and boulangerite. The mineralized layer is overlain by a distinctive pyrite-silica rock (halo?) about 0.5 to 6 feet thick. It is underlain by a weakly foliated sericite-quartz-carbonate unit derived at least in part from altered basalt; it contains 5-30 percent disseminated pyrite and veined pyrite. The deposit is probably similar to the Greens Creek Mine (Barnett and Miller, 2003; ARDF JU253) about 8 miles to the north, and like Greens Creek probably has gold and substantial silver values.
The Pyrola prospect was discovered in 1954 and has been drilled. It is on active claims within the Wilderness of the Admiralty Island National Monument.
Geologic map unit (-134.555772725814, 57.9625645285962)
Mineral deposit model Volcanogenic Ag-(Au?)-Cu- Pb-Zn massive sulfide deposit (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization Probably Triassic, analogous to the Greens Creek Mine (Barnett and Miller, 2003; ARDF JU253).
Alteration of deposit This massive-sulfide deposit is overlain by a distinctive pyrite-silica rock (halo?) about 0.5 to 6 feet thick. It is underlain by a weakly foliated pyrite-sericite-quartz-carbonate unit derived at least in part from altered basalt.

Production and reserves

Workings or exploration The Pyrola prospect was discovered in 1954 and has been drilled.
Indication of production None
Reserve estimates None have been published but may be significant.

Additional comments

The Pyrola prospect is on active claims within the Wilderness of the Admiralty Island National Monument.

References

References

Newberry, R.J., Crafford, T.C., Newkirk, S.R., Young, L.E., Nelson, S.W., and Duke, N.A., 1997, Volcanogenic massive sulfide deposits of Alaska, in Goldfarb, R.J. and Miller, L. D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 120-150.
Van Nieuwenhuyse, R., 1984, Geology and geochemistry of the Pyrola massive sulfide deposit, Admiralty Island, Alaska: Tucson, University of Arizona, M.A. thesis, approximately 300 p.
Reporters Donald Grybeck (U.S. Geological Survey)
Last report date 5/5/2005