Unnamed (southwest of Red Mountain)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Zn
Other commodities Ag; Cd; Mo; Pb
Ore minerals galena; hydrozincite; pyrite; smithsonite; sphalerite
Gangue minerals calcite

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale D-1
Latitude 58.966
Longitude -136.048
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The deposit is near the 1000-foot elevation on an outlier to Red Mountain in section 35, T. 33 S., R. 56 E., of the Copper River Meridian. The crest of Red Mountain is about 2.5 miles to the northeast of the site which is also about 2 miles east of the anchorage at Goose Cove. It is probably located within 0.2 mile.
The site is the same as number 20 of MacKevett and others (1971), number 44 of Cobb (1972), and number 72 of Kimball and others (1978).

Geologic setting

Geologic description

The occurrence is in the Black Cap Limestone of Devonian age, near a granodiorite cupola of probable Cretaceous age (MacKevett and others, 1971, p. 55). Pyrite-rich pods and impregnations as much as 10 feet long and 1 foot diameter occur in the limestone.
A representative sample collected by MacKevett and others (1971, table 9) contained 7000 ppm zinc, 500 ppm lead, 70 ppm cadmium, 1.5 ppm silver and an anomalous amount (30 ppm) of molybdenum. At the site, white incrustations, either hydrozincite or smithsonite, occur as secondary minerals on the pyrite-rich mass. Sphalerite is assumed to be the primary zinc mineral. Lead is abundant enough so that galena could exist as the primary lead mineral.
The pods are too small and lean to be of significance, but they are probably distal phases of the igneous-affiliated mineral deposits of the area. The existence of anomalous quantities of molybdenum suggests a distal relation to nearby molybdenum deposits, as at the Nunatak (MF036).
Geologic map unit (-136.049883673778, 58.965604957059)
Mineral deposit model Distal sulfide-rich replacement pods in limestone.
Age of mineralization Cretaceous or younger.

Production and reserves

Workings or exploration There are no workings. A sample of a partly oxidized sulfide pod in limestone exposed at the site contained 7000 ppm zinc, 500 ppm lead, 70 ppb cadmium, 30 ppm molybdenum and 1.5 ppm silver (MacKevett and others, 1971).
Indication of production None

Additional comments

MacKevett and others (1971, p. 55) thought that the deposits were too small to be of economic significance. The site is in Glacier Bay National Park and Preserve.

References