Nukalaska

Mine, Inactive

Alternative names

Honolulu Group

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cu; Te
Ore minerals arsenopyrite; chacopyrite; chalcocite; covellite; galena; gold; sylvanite; tetrahedrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SV
Quadrangle map, 1:63,360-scale C-2
Latitude 59.509
Longitude -150.667
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Nukalaska mine is on a precipitous north-facing slope below peak 2560 in the southwest part of the Seldovia C-2 quadrangle. The mine's camp was located on Sunny Cove, an embayment on the west arm of Nuka Bay. From the camp, a road was driven 1 1/4 miles to the mill site at an approximate elevation of 600 feet. The mill site was the terminus of an aerial tramway which rose 1,800 feet to the mine's portal about 235 feet north and 200 feet below the discovery outcrop. This Cobb's (1972, MF-397) location 17 and Richter's location 1. This location is accurate to within 300 feet.

Geologic setting

Geologic description

The host rocks of the mine are slate and graywacke of the Cretaceous Valdez Group that have been cut by quartz diorite dikes of Tertiary age (Richter, 1970). The deposit consists of a 10- to 18-inch-thick banded quartz vein that occurs along the footwall of a 12-foot-thick quartz diorite dike. The vein is younger than the dike; low-grade veinlets that divert into the dike are common. The vein strikes almost due east at a right angle to the graywacke country rock and dips 80S. The ore consists of somewhat banded quartz with free gold, arsenopyrite, pyrite, galena, and chalcopyrite. Microscopic examination by Yewell (Capp,1938) also identified tetrahedrite, chalcocite, and covellite. The gold appears to be localized within high-grade shoots within the vein.
From the top of the tramway the main haulage drift was driven 235 feet to intersect the vein. Two drifts were driven both east and west along the vein. The east drift was driven 200 feet but no significant mineralization was encountered. All the production came from the west drift. In 1936, the west stope was 140 feet long and 80 feet high along the 12- to 18-inch-wide vein. Concentrates from this stope carried 21 to 51 ounces of gold per ton; even though two-thirds of the mill feed was wall rock (Capps, 1938).
Geologic map unit (-150.669091547777, 59.5084128606596)
Mineral deposit model Low-sulfide, Au-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Tertiary; Boden and others (1991) report other veins in the district are about 55 m.y. old.
Alteration of deposit None reported although Borden and others (1991) report other veins in the Nuka Bay district show carbonization, sulfidization, sericitization, and silicification of the wall rock adjacent to the veins.

Production and reserves

Workings or exploration The mine was discovered in 1926 and developed in 1934-35. It produced from 1935 to 1940. In 1936, the west stope was 140 feet long and 80 feet high along the 12- to 18-inch-wide vein. Concentrates from this stope carried 21 to 51 ounces of gold per ton; even though two-thirds of the mill feed was wall rock (Capps, 1938). A fire in 1938 and snow slides in 1939 hampered mining. World War II closed the mine in 1942 and an attempt to reopen the mine after the war failed (Richter, 1970).
Indication of production Yes; small
Reserve estimates None reported.
Production notes The gold occurred in very high-grade shoots. Ore mined in 1936 yielded $100 per ton ($35 per ounce gold) even though two-thirds of the mill feed was country rock (Capps, 1938, p.27-29). The total production for this mine is unknown.

Additional comments

This mine is within Kenai Fjords National Park; the area is closed to mineral entry.

References

MRDS Number A010574

References

Reporters Jeff A. Huber (Anchorage)
Last report date 2/2/1999