Unnamed (northwest of Colorado Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Sn; Zn
Other commodities B; Be; Bi; Cd
Ore minerals azurite; cassiterite; malachite; and unspecified sulfides
Gangue minerals calcite; diopside; epidote; garnet; tourmaline; tremolite

Geographic location

Quadrangle map, 1:250,000-scale WI
Quadrangle map, 1:63,360-scale B-6
Latitude 67.405
Longitude -152.7667
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is located about 1.7 miles northwest of the junction of Colorado and Mettenpherg Creeks and about 5.8 miles east-northeast of the east end of Ernie Lake. The occurrence is at an elevation of about 1,100 meters, near the southeast corner of section 19, T. 30 N., R. 23 W., of the Fairbanks Meridian. The occurrence is the site of sample 224 in Dillon and others (1981 [AOF 133B]). The location is accurate.

Geologic setting

Geologic description

This occurrence consists of cassiterite, secondary copper minerals, and unspecified sulfides at or near the contact between Proterozoic(?) leucogranite and graphic granite, and marble (Dillon and others, 1981, samples 224 and 288 [AOF 133B]). Samples collected by Dillon and others (1981) include azurite- and malachite-stained granitic rock containing unspecified sulfides (sample 224) and skarn with disseminated cassiterite(?) and malachite staining (sample 288). The skarn consists of garnet, epidote, tremolite, and calcite, with scattered tourmaline and diopside(?). A sample of the granitic rock contains up to 20 ppm silver, 5,000 ppm copper, 700 ppm tin, 1,500 ppm zinc, 2,000 ppm boron, 20 ppm beryllium, 200 ppm bismuth, and 100 ppm cadmium. Samples of skarn contain up to 70 ppm bismuth, 150 ppm tin, and 1,500 ppm, zinc. The rocks in the area are mainly Proterozoic(?) granite gneiss and banded schist (Dillon and others, 1981).
Geologic map unit (-152.769464062558, 67.4045315370881)
Mineral deposit model Sn skarn deposit? (Cox and Singer, 1986; model 14b?).
Mineral deposit model number 14b?

Production and reserves

Workings or exploration Only surface sampling.
Indication of production None