Unnamed (east of Maclaren Glacier)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Cu; Sb
Ore minerals chalcopyrite; malachite
Gangue minerals ankerite; quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-6
Latitude 63.3236
Longitude -146.5015
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the east side of the Maclaren Glacier valley at about 4,250 feet elevation, in the SE1/4 section 25, T. 19 S., R. 6 E., Fairbanks Meridian. The location is approximate; it corresponds to locality A6 of Kurtak and others (1992), who gave a range of elevation of between 4,000 and 4,500 feet. The location is probably accurate within a quarter of a mile.

Geologic setting

Geologic description

The rocks near the occurrence are schist, argillite, and slate of late Paleozoic protolith age (Nokleberg and others, 1991). Quartz-ankerite veins about 0.2 foot wide cut across the metamorphic structure. Quartz veins, as much as 0.3 foot wide, in zones as much as 30 feet thick, parallel schistosity. Sulfides are sparse; the rocks are locally stained with malachite, suggesting that chalcopyrite occurs locally in the quartz-ankerite veins (Kurtak and others, 1992, p. 92). Quartz and quartz-ankerite veins contain small concentrations of metals. Of six total samples collected at the site, five contained from 2 to 3 parts per million (ppm) silver; a malachite-stained quartz-carbonate vein contained 276 ppm copper and 80 parts per billion (ppb) gold. Another quartz vein contained 185 ppb gold. Antimony is slightly enriched; three of the six samples contain from 20 to 45 ppm antimony (Kurtak and others, 1992).
Geologic map unit (-146.503768043057, 63.3231721648523)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Late Paleozoic or younger; possibly related to Cretaceous regional metamorphism (Nokleberg and others, 1982).
Alteration of deposit Oxidation of iron- and copper-bearing minerals.

Production and reserves

Workings or exploration There are no workings. The veins were discovered during U.S. Bureau of Mines study of the area (Kurtak and others, 1992).
Indication of production None