Headwall

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au; Sb; Sn
Other commodities Cu; Pb
Ore minerals arsenopyrite; bindheimite; bismuth; chalcopyrite; galena; pekoite; scorodite
Gangue minerals quartz; sericite; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale RM
Quadrangle map, 1:63,360-scale C-1
Latitude 61.658
Longitude -159.111
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is in the Russian Mountains on the northeast flank of the sharp ridge between the headwaters of Cobalt and Mission Creeks. The map site is in the SW1/4 sec. 8, T. 18 N., R. 54 W., of the Seward Meridian. It is at an elevation of about 2,350 feet, about 0.15 mile south-southwest of a small cirque-basin lake. It is sample locality 14 of Bundtzen and Laird (1991).

Geologic setting

Geologic description

The Headwall prospect is in syenite and includes several 10-foot wide banded tourmaline greisen zones that trend northwest for a distance of at least 790 feet (Bundtzen and Laird, 1991). The zones are exposed over a vertical range of 400 feet. The tourmaline greisens contain euhedral quartz, along with sericite and sulfide veinlets and clots. Arsenopyrite, native bismuth, pekoite, galena, bindheimite, and scorodite have been identified in the sulfide-rich assemblages (Bundtzen and Laird, 1991). The sulfide-bearing zones are disrupted by later faulting. Six channel samples average 3.3 ppm gold, 7.32 percent arsenic, 0.16 percent antimony, and 0.04 percent tin. Bismuth, copper, and lead analyses are not available. Assuming dimensions, in feet, of 4.45 x 400 x 790, Bundtzen and Laird (1991) estimated a resource of 82,900 tons of material with the stated average grades. The host rocks are part of the Upper Cretaceous intrusive complex of the Russian Mountains.
Geologic map unit (-159.113365282184, 61.6572853611163)
Age of mineralization Late Cretaceous or Tertiary. Greisens crosscut part of the intrusive complex of the Russian Mountains. Quartz monzonite from this complex has yielded a K/Ar age of 70.3 +/- 2.1 Ma (Bundtzen and Laird, 1991).
Alteration of deposit Silicification and tourmalinization.

Production and reserves

Workings or exploration Surface observation and sampling has been completed (Bundtzen and Laird, 1991).
Indication of production None
Reserve estimates Assuming dimensions, in feet, of 4.45 x 400 x 790, Bundtzen and Laird (1991) estimate a resource of 82,900 tons of material with average grades of 3.3 ppm gold, 7.32 percent arsenic, 0.16 percent antimony, and 0.04 percent tin. Bismuth, copper, and lead analyses are not available.

References