Black Mountain

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Sb
Ore minerals stibnite

Geographic location

Quadrangle map, 1:250,000-scale RM
Quadrangle map, 1:63,360-scale D-1
Latitude 61.791
Longitude -159.304
Nearby scientific data Find additional scientific data near this location
Location and accuracy Black Mountain, unnamed on the USGS 1:63,360 topographic map (1952 edition) of the area, is an isolated 1585-foot-high upland about 2.3 miles southwest of Molybdenum Mountain. The map site is 0.25 mile south of the summit of Black Mountain at an elevation of about 1,350 feet. It is in the SW/4 sec. 29, T. 20 N., R. 55 W., of the Seward Meridian. This is locality 3 of Hoare and Cobb (1972, 1977). Hoare and Coonrad (1959) show a prospect symbol at this location.

Geologic setting

Geologic description

A single, 2-inch wide, stibnite-bearing vein in shaly sandstone was traced for a distance of 200 feet at this location (Ebbley and Wright, 1948). The vein trends subparallel to the contact between clastic sedimentary country rocks and a granitic stock upslope to the north of the vein (Ebbley and Wright, 1948; Hoare and Coonrad, 1959). Host rocks to the vein are not altered, and only one vein has been identified at this prospect. A sample collected along 50 feet of the vein contained 48.9 percent antimony, 0.02 ounce of gold per ton, and 0.2 ounce of silver per ton (Ebbley and Wright, 1948). The sedimentary rocks may either be part of the mid-Cretaceous Kuskokwim Group (Hoare and Coonrad, 1959), or possibly an upper Paleozoic or Mesozoic section correlative with parts of the Gemuk Group (Bundtzen and Laird, 1991). The nearby granitic rocks may be part of a Cretaceous or Tertiary igneous assemblage that is widespread through southwest Alaska.
Geologic map unit (-159.306368520304, 61.7902859718959)
Mineral deposit model Simple Sb deposits (Cox and Singer, 1986; model 27d)
Mineral deposit model number 27d
Age of mineralization Cretaceous or Tertiary (?). The vein crosscuts clastic sedimentary rocks that may range in age from lare Paleozoic to mid-Cretaceous (Bundtzen and Laird, 1991). The nearby granitic rocks may be Cretaceous or Tertiary.

Production and reserves

Workings or exploration Cady and others (1955) reported that claims have been staked on the prospect. Some small pits or trenches are probably present.
Indication of production None