About 50 percent of the nickel and cobalt is believed to exist in pyrrhotite; the remainder is in pentlandite and other nickleiferous and cobaltiferous minerals.
Location: The Chip-Loy deposit is located on a steep valley wall of Straight Creek at an elevation ranging from 2,900 feet (884 m) to 4,000 feet (1,220 m) in the SW1/4 sec. 15, T. 24 N., R. 28 W., of the Seward Meridian. Location is precisely known and visited by the reporter in 1983 and 1998. Caution: the precipitous, steep slopes that contain the Chip-Loy deposit are considered dangerous and are unsafe for traversing.
Geology: According to Herreid (1968), Foley (1987), Nokleberg and others (1987), and Foley and others (1997), the Chip-Loy deposit consists of an irregular, steeply dipping layer of massive to disseminated, nickelian pyrrhotite accompanied by other sulfides in an elongate, composite, diabase intrusion. Herreid (1968) describes the diabase, which ranges from gabbro to diorite, as a pipe in plane view, but Smith and Albanese (1985) describe the same intrusion as a dike. The diabase trends in a northeast direction and varies from 40 meters to 260 meters wide; cliff walls prevent accurate investigations of the intrusion's true dimensions. The composite diabase intrusion cuts mid-Silurian Terra Cotta Mountains Sandstone, a formation of the Dillinger subterrane, a continental margin assemblage of Lower Paleozoic age. (Bundtzen, Harris, and Gilbert, 1997). Although undated, Gilbert and others (1988) assign the mineralized diabase intrusion an early Tertiary age. The Chip-Loy deposit contains disseminated-to-massive sulfides, mainly pyrrhotite and chalcopyrite, and minor cubanite, and sphalerite, and trace galena, bravoite, violarite, tetradymite (Bi2Te2S), and undetermined Co-Ni-Fe arsenides (Bart Cannon, written communication, 1998). The sulfides are interwoven with ilmenite and other rock-forming minerals such as plagioclase and olivine. The northeast trending, sulfide-bearing zone occurs within the diabase about 10 to 30 meters away from the contact with sandstone and shale. The zone is about 335 meters long and 10 to 15 meters wide, but is quite irregular along strike. Herreid (1968) estimated that the Chip-Loy deposit contained an inferred reserve of about 150,000 tonnes of disseminated and massive sulfide mineralization. Smith and Albanese (1985) suggested a larger reserve than Herreid; they estimate from 0.15 to 1.25 million tonnes of sulfide mineralization exist at the Chip-Loy deposit. Chip-channel samples from the Chip-Loy deposit contain up to 3.30 percent nickel, 0.25 percent cobalt, 2.10 percent copper, 12.1 grams/tonne silver, and 43.2 percent iron (Smith and Albanese, 1985; Bundtzen, Roberts, and others, 1982). A single sample of massive sulfide mineralization contained 3.0 grams/tonne gold (Foley, 1987; Gilbert and others, 1988). Tetradymite was found in solid solution with rock-forming silicates--a typical PGE association--although no PGE has ever been detected in analyses of mineralized rock from the Chip-Loy deposit. A 12-meter-long chip-channel sample taken midway across the strike of the deposit contained 0.28 percent copper, 2.6 grams/tonne silver, 444 ppm cobalt, 0.70 percent nickel, and 17.82 percent iron (Smith and Albanese, 1985; Gilbert and others, 1988). Pyrrhotite from selected samples averages 0.4 percent cobalt and 1.5 percent nickel (Bart Cannon, written communication, 1998).
Workings: The Chip-Loy deposit was discovered and staked by prospectors Ed Chipp and Robert Loy in the early 1960s. Surface samples have been collected and analyzed by Herreid (1968), Bundtzen, Roberts, and others (1982), Smith and Albanese (1985), Roberts (1985), Gilbert and others (1988), Foley (1987), and T.K. Bundtzen and G.M. Laird (written communication, 1998). Chip-channel sample intervals from the Chip-Loy deposit run up to 3.30 percent nickel, 0.25 percent cobalt, 2.10 percent copper, 12.1 grams/tonne silver, and 43.2 percent iron. A 12 meter-long, chip-channel sample taken across the strike of the mineralized zone contained 0.70 percent nickel, 444 ppm cobalt, 0.25 percent copper, 2.6 grams/tonne silver, and 17.82 percent iron (Smith and Albanese, 1985; Gilbert and others, 1988).
Age: Unknown; thought to be early Tertiary by Gilbert and others (1988).
Alteration: Slight oxidation of massive sulfides.
Reserves: Herreid (1968), who provides the only detailed geologic map of the Chip-Loy deposit, estimated that approximately 150,000 tonnes of disseminated-to- massive sulfide mineralization exists on site. Smith and Albanese (1985) estimate that between 0.15 and 1.25 million tonnes of disseminated to massive mineralization exist at the Chip-Loy deposit.

Commodities (Major) - Co, Cu, Ni; (Minor) - Ag, Au, Fe
Development Status: No
Deposit Model: Gabbroic Ni-Cu (Cox and Singer, 1986; model 7a).

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Commodity List

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Mineral List

9 valid minerals.