Unnamed (east of Kashoto Glacier)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Au; Mo
Ore minerals chalcopyrite; 'gray' sulfides; pyrite

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale D-4
Latitude 58.875
Longitude -137.036
Nearby scientific data Find additional scientific data near this location
Location and accuracy The most probable location of this occurrence is near tidewater in Johns Hopkins Inlet, north and east of the foot of Kashoto Glacier; the coordinates are probably within a 0.25 mile radius of the occurrence. An element of uncertainty is present because MacKevett and others (1971) say the location is east of Hoonah Glacier, the next glacier to the south. It is apparently the same location as number 33 of Kimball and others (1978). Location number 32 of Kimball and others (1978) is about 0.75 mile to the north.

Geologic setting

Geologic description

Disseminated pyrite and a trace of chalcopyrite occur in an altered zone several hundred feet thick of biotite hornfels adjacent to a granodiorite intrusion of Cretaceous age (Brew and others, 1978). The altered zone is conspicuously iron stained. The area was not well examined; grab samples contained as much as 700 ppm copper. The U.S. Bureau of Mines (Kimball and others, 1978, location 32, p. C173) reported disseminated pyrite, pyrrhotite and occasional bornite at a location about 0.75 miles north of the probable location of the occurrence. Copper content was less than 200 ppm in two chip samples collected from that area, and the report of bornite may be erroneous.
Geologic map unit (-137.037875792508, 58.8745913930397)
Mineral deposit model Disseminated deposit, igneous-affiliated contact metamorphism.
Age of mineralization Tertiary.
Alteration of deposit Contact metamorphism and formation of hornfels. Sulfidation; abundant secondary iron-staining.

Production and reserves

Workings or exploration There are no workings or pits. Two samples of hornfels (Location 77, MacKevett and others, 1971, table 9) contained 300 and 700 ppm copper.
Indication of production None

Additional comments

Only a small part of altered zone was examined, hence there may be richer sites. The U.S. Bureau of Mines party failed to thoroughly examine the occurrence because of attacks by vicious seagulls. The occurrence is in Glacier Bay National Park and Preserve.

References