Eb No. 4

Prospect, 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 63.2528
Longitude -146.1887
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Eb No. 4 prospect is at an elevation of 3,950 feet on the north-facing slope of a hill a mile south of upper Eureka Creek. The prospect is about 500 feet southeast of the center of section 22, T. 19 S., R. 8 E., Fairbanks Meridian. The location is accurate within one-tenth mile.

Geologic setting

Geologic description

The Eb No. 4 prospect is hosted by the Fish Lake mafic-ultramafic complex, a lopolithic feeder of Late Triassic age of the Nikolai basalt flows (Nokleberg and others, 1991). The prospect lies in lower portion of the gabbroic unit of the second magmatic cycle of the Fish Lake ultramafic complex (W.T. Ellis, unpublished data, 1996).
The prospect consists of float of sulfide-bearing coarse-grained pyroxenite; samples assay as much as 0.1 percent copper, 0.08 percent nickel, 140 parts per billion (ppb) palladium, and 85 ppb platinum. The metallic minerals are mainly pyrrhotite, along with chalcopyrite and pentlandite. The deposit does not crop out, but a good geophysical conductor is present that has been interpreted to be caused by sulfide accumulations (W.T. Ellis, unpublished data, 1996). Twelve hundred feet along strike a drill hole intersected 54 feet of pyroxenite grading 0.1 percent copper, 0.15 percent nickel, 198 ppb palladium, and 123 ppb platinum. This pyroxenite contained from 7 to 10 percent sulfides (W.T. Ellis, unpublished data, 1996).
Geologic map unit (-146.190958666709, 63.2523759789684)
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