Bonneville County Idaho Gold Production
By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Click here for the Principle Gold Producing Districts of the United States Index
The total recorded gold production of Bonneville County, about 16,600 ounces, was from the Mount Pisgah district, in T. 4 S., R. 44 E., in the Caribou Mountains.
Both placer and lode mines were productive, but all the recorded production was from placers, which in the 1870's yielded $250,000 in gold annually (Mansfield, 1927, p. 348). In later years mining in the district declined, although some time after 1920 several unsuccessful attempts were made at dredging. From 1939 through 1959 only 459 ounces of gold was produced.
The geology of the district was outlined briefly by Ross (1941, p. 26), who stated that most of the country rock consists of Mesozoic sedimentary rocks cut by dioritic dikes and sills. The deposits were described as large tabular masses of quartz that were shattered and then mineralized with calcite and auriferous pyrite. In most of the deposits, the pyrite is oxidized and the gold is free.