Prospect, Active

Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale A-6
Latitude 63.24
Longitude -149.61
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Jumbo prospect is at an elevation of about 2,200 feet on the south bank of the West Fork Chulitna River, about 0.5 mile from the junction of Bryn Mawr Creek. It is in sec. 26, T. 19 S., R. 11 E., of the Fairbanks Meridian. The location is accurate to within 1 mile. This is locality 7 of Cobb (1978: OFR 78-1062). According to Capps (1919), the Jumbo prospect adjoins the Riverside prospect (HE033).

Geologic setting

Geologic description

Bunches and specks of sulfides, mainly pyrrhotite along with some pyrite and chalcopyrite, are disseminated in Triassic conglomerate adjacent to a porphyry dike. The dike is similar in composition to the Upper Cretaceous porphyry at the Golden Zone mine (HE043).
Geologic map unit (-149.612291747007, 63.2395272315495)
Mineral deposit model Cu porphyry (Cox and Singer, 1986; model 18a)
Mineral deposit model number 18a
Age of mineralization Probably Late Cretaceous or younger.

Production and reserves

Workings or exploration Only open-cut surface workings.
Indication of production None