Unnamed (southeast of head of Twelvemile Arm)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale B-3
Latitude 55.30813
Longitude -132.68228
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is locality 3 of Herreid and Rose (1966). It is about 3.5 miles southeast of the head of Twelvemile Arm, and about 0.3 mile west of the center of section 5, T. 76 S., R. 84 E., of the Copper River Meridian.

Geologic setting

Geologic description

This occurrence is a planar quartz vein about 1 inch thick that contains chalcopyrite (Herreid and Rose, 1966). The vein cuts highly deformed amygdaloidal greenstone marked by ptygmatically-folded quartz-calcite veins. The rocks in the vicinity are greenstone, greenschist, and minor calcareous metagraywacke; they are part of the Wales Group of Late Proterozoic and Cambrian age (Eberlein and others, 1983; Brew, 1996). A few hundred yards to the west, Herbert and Race (1964) found chalcopyrite in limestone; a sample contained 0.3 percent copper.
Geologic map unit (-132.683931879102, 55.3077779095561)
Mineral deposit model Chalcopyrite in quartz vein in greenstone.
Age of mineralization Unknown other than that the mineralization is in rocks of Cambrian or older age.

Production and reserves

Indication of production None

Additional comments

This occurrence is on land that has been conveyed to the Sealaska Corporation, who hold the surface and subsurface rights, or the land is under application for transfer to them.