Lucky 7

Occurrence, Active

Commodities and mineralogy

Main commodities Cu; Ni; Pd; Pt
Ore minerals chalcopyrite; pentlandite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.2615
Longitude -146.2105
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Lucky 7 occurrence is at an elevation of 3,700 feet on the north-facing slope of a hill about one-half mile south of upper Eureka Creek. It is in the SE1/4SE1/4 section 16, T. 19 S., R.8 E., Fairbanks Meridian.

Geologic setting

Geologic description

The Lucky 7 occurrence is hosted by the Fish Lake mafic-ultramafic complex, which is considered to be a lopolithic feeder to the basalt flows of the Upper Triassic Nikolai Greenstone (Nokleberg and others, 1991).
The occurrence consists of disseminated sulfides in a melagabbro in the lower part of the gabbroic unit of the second magmatic cycle of the Fish Lake complex (W.T. Ellis, unpublished data, 1996). The gabbroic package at the site includes leucocratic taxitic gabbro, troctolite, two-pyroxene gabbro, gabbronorite, and olivine melagabbro. The sulfides are disseminated in a 5-foot-thick melagabbro layer. The layer strikes about southeast and dips 45 degrees south. Sulfides, chiefly pyrrhotite and trace amounts of chalcopyrite and pentlandite, form 3 to 7 percent of the rock. Samples contain as much as 0.14 percent copper, 0.17 percent nickel, 94 parts per billion (ppb) palladium, and 94 ppb platinum (W.T. Ellis, unpublished field data, 1996).
Geologic map unit (-146.21275973017, 63.2610759035031)
Mineral deposit model Ni-Cu-PGE in differentiated mafic-ultramafic sill.
Age of mineralization Late Triassic, the age of the host rock.

Production and reserves

Workings or exploration The occurrence is on active Fort Knox Gold Resource claims.
Indication of production None