Jimmy Lake

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Mo; Pb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; molybdenite; sphalerite
Gangue minerals albite; fluorite; kaolinite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale LH
Quadrangle map, 1:63,360-scale C-1
Latitude 61.734
Longitude -153.1979
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at ane elevation of about 5,000 feet, in the head of a cirque valley, 1.4 miles northeast of Jimmy Lake. The map site is in the southwest 1/4 of section 13, T 19 N, R 22 W, of the Seward Meridian. This is locality 12 of Cobb (1972 [MF 412]; 1976 [OF 76-485]) and locality 11 and 12 of Gamble and others (1989). The location is probably accurate to within 1/4 mile.

Geologic setting

Geologic description

Reed and Elliott (1970) reported that an altered and mineralized biotite granite stock is present at this locality. Mineralization, mostly identified in float boulders and cobbles, includes (1) altered granite that contains less than 5 percent disseminated galena and sphalerite, (2) altered granite that contains veinlets of quartz, sphalerite, galena, and chalcopyrite, and (3) altered granite that contains a 1-inch-wide quartz-molybdenite vein. The alteration consists of variably developed replacement of granite by quartz, sericite, kaolinite, and albite. Samples contain as much as 15,000 ppm copper, 300 ppm silver, and greater than 20,000 ppm lead, 2,000 ppm molybdenum, and 10,000 ppm zinc. Stream sediment samples from the area contain high contents of silver, arsenic, copper, lead, and zinc. The biotite granite stock contains accessory fluorite and intrudes upper Mesozoic clastic sedimentary rocks and possibly overlying Tertiary volcanic rocks (Cobb and Reed, 1981).
Geologic map unit (-153.200121265114, 61.7333830165144)
Mineral deposit model Polymetallic veins? and porphyry Cu-Mo? (Cox and Singer, 1986, models 22c and 21a)
Mineral deposit model number 21a?, 22c?
Age of mineralization Tertiary. Mineralization crosscuts Tertiary granite.
Alteration of deposit Granite locally replaced by quartz-sericite-kaolinite-albite assemblages.

Production and reserves

Workings or exploration Reconnaissance sampling has been completed in this area (Reed and Elliott, 1970).
Indication of production None

References