Silver Lining Prospect, Fortymile District, Southeast Fairbanks Borough, Alaska, USA

Location: The Silver Lining prospect is located approximately 42 road miles northeast of Tok in the north-central Tanacross (C-3) quadrangle. The prospect is located at the 30-mile marker of the Taylor Highway, at an elevation of 3000 to 3500 feet on the southwest flank of Mt. Fairplay, within T. 22 N., R. 16 E., of the Copper River Meridian (Curt Freeman, unpublished data, 1992). The location is accurate to within 1 to 2 miles.
Geology: The Silver Lining prospect is the Mt. Fairplay biotite syenite which is flanked to the west by Tertiary mafic volcanic rocks and to the east by biotite-quartz gneiss and schist (Foster, 1970). The Mt. Fairplay syenite has a K/Ar date of 67 +/- 2 Ma (Wilson and others, 1985). The prospect is notable for north-northeast linear structures. The mineralization consists of gold, silver, copper, arsenic, lead, zinc, and antimony mineralization hosted by quartz-clay altered shear zones in the biotite syenite. Minerals found include arsenopyrite, chalcopyrite, and galena. The mineralization is controlled by northeast-trending structures that cross-cut a strong northwest joint fabric. Rock samples contain up to 0.255 ounces per ton gold, 62 ounces per ton silver, 6.4 percent copper, and 4.7 percent lead (Curt Freeman, unpublished data, 1992). The regional geology consists of Upper Proterozoic to Lower Paleozoic polymetamorphic rocks ranging from biotite-quartz gneiss to quartz-muscovite-garnet schist (Foster, 1970). This basement assemblage is intruded by numerous intermediate Mesozoic to Tertiary intrusions and is capped by Tertiary mafic and felsic volcanic rocks (Foster, 1970).
Workings: Minor surface rock sampling.
Age: Tertiary or younger.
Alteration: Host syenite is altered to clay and cut by quartz-clay fractures.

Commodities (Major) - Ag, Au, Cu, Pb; (Minor) - As, Sb, Zn
Development Status: None

Mineral List

12 entries listed. 9 valid minerals.

References