Unnamed (in Port Dick)

Prospect, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cu; Zn
Ore minerals arsenopyrite; chacopyrite; gold; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SV
Quadrangle map, 1:63,360-scale B-4
Latitude 59.313
Longitude -151.357
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospects are about a mile and a quarter west of the head of Port Dick in the NW 1/4 section 17, T.10 S., R. 12 W., of the Seward Meridian, and the NE 1/4 of section 18, T.10 S., R. 12 W., of the Seward Meridian. The lower adit is about 200 feet above sea level, and the upper adit is about 500 feet above sea level. This is Cobb's (1972, MF-397) location 14. This location is accurate within a quarter of a mile.

Geologic setting

Geologic description

The country rock at the head of the West Arm of Port Dick is hornfelsed graywacke and greenstones of the Cretaceous Valdez Group that have been intruded by fine-grained biotite granite dikes of Tertiary age (MacKevett and Holloway, 1978). The quartz veins are nearly vertical and cut both the granite dikes and the graywacke. The lower prospect is at about 200 feet of elevation where an adit 140 feet long was driven on a vein that strikes N54W and dips 75 to 85N. The vein ranges from 6 to 20 inches in width and averages 15 inches thick. The vein consists of quartz with segregations of arsenopyrite and pyrite that give the vein a banded appearance. The upper vein at an elevation of about 500 feet is about 500 feet to the south. It is about 24 inches thick. An adit 310 feet long has been driven N69W along strike on the vein. The upper vein is similar to the lower vein and contains traces of sphalerite and small fractures filled with calcite. The wall rock is a fine-grained granite (Brooks, 1909).
Geologic map unit (-151.359090869523, 59.3123790276919)
Mineral deposit model Low-sulfide, Au-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Tertiary; veins cut Tertiary granite dikes.
Alteration of deposit None reported.

Production and reserves

Workings or exploration Several hundred feet of tunnels were driven in 1899, and 1904 through 1907 by the Alaska Commercial Company. A grab sample provided to Brooks (1909) assayed at 0.123 ounces of gold and 1.32 ounces of silver per ton. There is no reported production from this location.
Indication of production None
Reserve estimates None reported.
Production notes None reported.

Additional comments

This prospect is within Kachemak Bay State Wilderness Park; the area is withdrawn from mineral entry.

References