According to Herreid (1968), Foley (1987), and Foley and others (1997), the Chip-Loy deposit consists of an irregular, steeply dipping layer of massive to disseminated, nickelian pyrrhotite and other sulfides in an elongate, composite, diabase intrusion. Herreid (1968) describes the diabase, which ranges from gabbro to diorite, as a pipe in plan view, but Smith and Albanese (1985) describe it 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 of Lower Paleozoic age. (Bundtzen, Harris, and Gilbert, 1997). Gilbert and others (1988) assign an early Tertiary age to the mineralized diabase intrusion.

The Chip-Loy deposit contains disseminated to massive sulfides, mainly pyrrhotite and chalcopyrite, with 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 intergrown with ilmenite and other rock-forming minerals such as plagioclase and olivine. The northeast trending, sulfide-bearing zone is in the diabase about 10 to 30 meters 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 contains 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 0.15 to 1.25 million tonnes of sulfide mineralization.

Chip-channel samples from the Chip-Loy deposit contained up to 3.30 percent nickel, 0.25 percent cobalt, 2.10 percent copper, 12.1 grams of silver per tonne, and 43.2 percent iron (Smith and Albanese, 1985; Bundtzen and others, 1982). A single sample of massive sulfide mineralization contained 3.0 grams of gold per tonne (Foley, 1987; Gilbert and others, 1988). Tetradymite is in the interstices of the rock-forming silicates. A 12-meter-long chip-channel sample across the deposit contained 0.28 percent copper, 2.6 grams of silver per tonne, 444 parts per million (ppm) cobalt, 0.70 percent nickel, and 17.82 percent iron (Smith and Albanese, 1985; Gilbert and others, 1988). Pyrrhotite from selected samples averaged 0.4 percent cobalt and 1.5 percent nickel (Bart Cannon, written communication, 1998). About 50 percent of the nickel and cobalt is in pyrrhotite; the remainder is in pentlandite and other nickel and cobalt minerals.