Frying Pan Lake Prospect, Bristol Bay Mining District, Lake and Peninsula Borough, Alaska, USAi

Regional Level Types
Frying Pan Lake Prospect	Prospect
Bristol Bay Mining District	Mining District
Lake and Peninsula Borough	Borough
Alaska	State
USA	Country

Location: This prospect is centered on hill 1760 about 1.3 miles west of lake 943, locally called Frying Pan Lake. The site is in the E1/2 sec. 5, T. 4 S., R. 35 W., Seward Meridian. The location is at the approximate center of the outcrop area of the deposit, which extends outward from the site for as much as a mile. The prospect is location 1 of Detterman and Cobb (1972).
Geology: This prospect is a body of plutonic breccia approximately 1 square mile in outcrop area that consists of angular, magnetite-bearing pyroxenite fragments in a matrix of Tertiary or Cretaceous granodiorite (Reed and Detterman, 1965). Pyroxenite clasts constitute 50-90 percent of the breccia, and magnetite occurs in crystal aggregates as much as 1 inch across. Sixteen samples of breccia collected by Reed and Detterman (1965) contained 16 to 24 percent FeO, about 1.3 percent TiO2, 0.1 to 3.2 percent P2O5, and 0.1 to 0.15 percent V2O5. A magnetic concentrate of the material contained about 3.5 percent TiO2, reflecting the presence of ilmenite or titaniferous magnetite. Samples collected by Fischer (1975) contained about 0.02 percent V2O5, less than was reported by Reed and Detterman. Fischer's magnetite-rich concentrate of the pyroxenite contained 40-60 percent iron, 3.1 percent TiO2, and 0.3-0.5 percent vanadium (Fischer, 1975). Bouley and others (1995) reported considerable amounts of iron in two samples of biotite pyroxenite collected in the prospect area. Their sample 10 (table 2) contained 18.78 percent iron (as Fe203). The rocks are also highly potassic and are similar to alkali ultramafic rocks in composite plutons elsewhere in the central Alaska Range (Foley and others, 1997).
Workings: Exploration has been limited to geologic mapping and surface sampling. Sixteen samples assayed by Reed and Detterman (1965) contained 16 to 24 percent FeO, 1.3 percent TiO2, 0.1 to 3.2 percent P2O5, and 0.1 to 0.15 percent V2O5. Samples analyzed by Fischer (1975) contained 12 to 19 percent Fe, 1.3 percent TiO2, and 0.02 percent V2O5. A sample analyzed by Bouley contained about 19 percent Fe (Bouley and others, 1995).
Age: The pyroxenite is probably Late Cretaceous but probably predates the 90 Ma Pebble Copper deposit (IL007), whose granodiorite hostrock is presumed to be the matrix of the plutonic breccia at the Frying Pan Lake prospect.
Reserves: Fischer (1975) estimated a resource of 7 billion tons of magnetite-bearing breccia that contained 7 million tons of vanadium.

Commodities (Major) - Fe; (Minor) - Ti, V
Development Status: None
Deposit Model: Alaska PGE (Cox and Singer, 1986; model 9).

Other Databases

Link to USGS - Alaska:	IL006

Other Regions, Features and Areas containing this locality

References