Unnamed (northeast of Brooker Mountain)

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Sb; Zn
Ore minerals cerussite; galena; limonite; malachite; smithsonite; sphalerite; tetrahedrite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-3
Latitude 63.509
Longitude -151.0323
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 2680 feet on a southeast-trending ridge about midway between Brooker Mountain and Alpha Ridge. It is approximately on the boundary between sections 21 and 22, T. 16 S., R. 18 W., Fairbanks Meridian. The location is probably accurate within 300 feet. The prospect is number 5 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

This prospect is in a high-angle(?) fault in the the hanging wall of a probable low-angle fault that places Birch Creek Schist above Spruce Creek rocks in the upper Eldorado Creek area (Thornsberry, McKee, and Salisbury, 1984, pl. K-6). The high-angle fault strikes NNE. The deposit is in quartz-mica and feldspar-quartz-mica schist of the Birch Creek Schist (Bundtzen, 1981).
The deposit consists of oxidized, polymetallic veins. Gossan in shallow, caved pits locally is coated with malachite. Sulfide-bearing gossan in one pit contains tetrahedrite. The presence of galena or its oxidation product cerussite, and of sphalerite or an oxidation product such as smithsonite, is inferred from analyses of the tetrahedrite-bearing sample, which assayed 5.16 ounces of silver per ton, 1.25 percent copper, 4.45 percent lead, 33 percent zinc, and 2.45 percent antimony. Another sample of gossan assayed 7.2 ounces of silver per ton and 2.95 percent zinc (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence number 5).
Geologic map unit (-151.034584721194, 63.508491169707)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization The deposit is assumed to be Eocene (see record MM091).
Alteration of deposit Oxidation of sulfide minerals.

Production and reserves

Workings or exploration The prospect was explored by four hand-dug pits of unknown date.
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.

References