The U.S. Bureau of Mines conducted a mineral investigation of the 95,850-acre Bear Creek and 18,600-acre Poker Peak roadless areas in the Caribou National Forest during 1991. Lying within the western overthrust belt, the area is underlain by Paleozoic to Cenozoic sedimentary rocks, which have been complexly folded and thrust- faulted. Phosphate resources of at least 41 million tons have been delineated in the known phosphate leasing area within the study area. Phosphate leases in the study area are held by Western Cooperative Fertilizers Ltd. Travertine used for dimension stone is being mined from a 150-million-cubic-foot resource adjacent to and extending into the study area. Although two wells have been drilled in the area, all oil and gas leases in the study area expired in 1991. Placer gold has been intermittently mined from McCoy Creek since the 1860's, with 275 troy ounces of gold recovered from 66,000 cubic yards of gravel from within the study area. Placer gold resources examined by the Bureau of Mines averaged $0.33 Per cubic yard of gravel at a gold price of $353 per troy ounce. The value is too low for the gold to be economically mined at large scale, but some may be recoverable by recreational-size suction dredges in sections of McCoy Creek along the southern boundary of the study area. Twelve placer claims blanket the Travertine deposit, and 30 placer claims are along McCoy Creek. There are no lode mining claims in the study area.