Records of the Philipsburg Mining Company, of Philipsburg, Montana, consist of interoffice correspondence between the Philipsburg office, the St. Louis office, and the sales office in Cincinnati; general correspondence; financial records, consisting primarily of vouchers; production records, including assay reports and manganese ore shipment records; accident reports; and miscellany.

The Trout Mining Company produced manganese oxide for batteries. Records consist of scattered correspondence (1939-1951); payroll records (1956-1959), orders for equipment and supplies (1946-1953); production records, including a sample book (1958) for the Blaine Mine; reports; and miscellany, including field survey books (1936-1938).