Collection consists predominantly of subject files kept by Gustaf "Gus" M. Carlson and his father Gustaf "Gust" Carlson on local mines including the Spring Hill (near Unionville), the Klondyke and the Sourdough (in Elkhorn); the East Pacific and the Kleinschmidt (near Townsend); the Drumlummon (near Marysville); mines in the Corbin and Wickes area; and other mines in Montana and Idaho. The most extensive files concern the Spring Hill Mine (near Unionville), owned by the Montana Consolidated Mines Corporation, and includes daily mine production reports (1939-1940), diamond drilling records, and level books. Also included are general subject files on mining processes and maps [OVERSIZE MATERIAL: Map Case] of Iron Ore and Eureka Gulches, Leslie Lake Group, the Skyline, and mines and claims near Corbin and Marysville. [Photographs and maps transferred to the Photograph Archives and Library respectively].