Brewer Alaska

Prospect, Inactive

Alternative names

Brewster
Mile Seven
Sevenmile

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Pb; Zn
Ore minerals arsenopyrite; galena; gold; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale A-7
Latitude 60.2285
Longitude -149.408
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located in the SW1/4 section 26, T. 2 N., R. 1 W., of the Seward Meridian. It is situated on the east side of Lost Creek at an elevation of about 1,400 feet. This is location 85 of Cobb and Tysdal (1980) and location S-205 of Jansons and others (1984). Cobb and Tysdal (1980) summarized this prospect under the name Mile Seven. This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The prospect consists of a 12- to 20-inch-wide quartz-calcite vein that is discontinuously traceable for at least 300 feet. The vein generally parallels the north-south strike of the bedrock and dips steeply to the east (Hoekzema and Sherman, 1983). It is vuggy and has a well-developed ribbon structure. Metallic minerals included arsenopyrite, galena, sphalerite, and gold. The host rock is a blue-black slate of the Valdez Group of Late Cretaceous age (Tysdal, 1978 [MF-880-A]). Workings on the prospect consist of three adits totalling 220 feet in length. The main adit is at an elevation of about 1,400 feet; it consists of a 60-foot crosscut and 110 feet of drift with some stoping. Two short adits with winzes are located about 250 and 750 feet south of the main adit. Improvements included a 2-stamp mill and several cabins (Johnson, 1914 [B 592-G, p. 237-243]).
There is no reported production. Eight assay samples contained between less than 0.1 ppm and 28.5 ppm gold (Hoekzema and Sherman, 1983).
Geologic map unit (-149.410152741299, 60.2279403392777)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger; the vein cuts rocks of the Valdez Group of Late Cretaceous age.

Production and reserves

Workings or exploration Workings consist of three adits totalling 220 feet in length. The main adit is at an elevation of about 1,400 feet; it consists of a 60-foot crosscut and 110 feet of drift with some stoping. Two short adits with winzes are located about 250 and 750 feet south of the main adit. Improvements included a 2-stamp mill and several cabins (Johnson, 1914 [B 592-G, p. 237-243]). Eight assay samples taken from the main adit and near the portals of the two short adits, contained between less than 0.1 ppm and 28.5 ppm gold (Hoekzema and Sherman, 1983).
Indication of production Undetermined
Reserve estimates The U.S. Bureau of Mines estimated 1,100 tons of ore containing 0.3 ounce of gold per ton and 0.3 ounce of silver per ton ( Hoekzema and Sherman, 1983).

Additional comments

The gold to silver ratio in the eight samples collected by the U.S. Bureau of Mines is 1:1 (Hoekzema and Sherman, 1983). An indicated resource with a 1:1 gold to silver ratio is suspect.

References

References

Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 1/12/2001