Unnamed (near Desolation Glacier)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu; Ni
Other commodities Au; Ti
Ore minerals chalcopyrite; ilmenite; pentlandite; pyrite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale D-5
Latitude 58.78
Longitude -137.57
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is on the north side of Desolation Glacier about 1.5 miles above its foot and between 3000 and 4000 feet elevation. The location is accurate within about 0.25 mile; it is approximately the same as number 17 of Kimball and others (1978).

Geologic setting

Geologic description

Disseminated pyrrhotite, pyrite, chalcopyrite occur in a 'gabbro diabase' dike with average width of 5-6 ft that is exposed for 200 feet . The rock also contains a reported 2-5 percent titanium and probably contains ilmenite. An average grade reported is 0.59 percent nickel, 0.62 percent copper, and 0.010 ounce per ton in gold (Mark-Anthony, 1977). Based on the content of nickel, pentlandite is probably present .
The dike cuts the hornblende schist and gneiss unit of Brew and others (1978). Based on the mid-Tertiary age of the nickel-bearing layered mafic intrusions of the Fairweather Range (Goldfarb, 1997), the mafic dike probably is also Tertiary. Brew and others (1978) considered the pre-metamorphic age of the schist host rocks as possibly Precambrian; Berg and others (1972) interpreted it as Mesozoic.
Geologic map unit (-137.5719093835, 58.7796383441682)
Mineral deposit model Mineralized mafic dike probably affiliated with layered gabbro intrusions.
Age of mineralization Tertiary.

Production and reserves

Workings or exploration Average value from surface exposures was reported to be 0.59 percent nickel, 0.62 percent copper, and 0.01 ounce per ton gold; titanium ranged from 2-5 percent (Mark-Anthony, 1977, cited by Kimball and others, 1978, p. C124). The occurrence was found by private prospectors.
Indication of production None

Additional comments

Small deposit, but worthy of additional followup because of its grade. It was not found by the Bureau of Mines investigators in 1977 (Kimball and others, 1978, p. C124) during stormy weather.
The occurrence is in Glacier Bay National Park and Preserve.

References