Records include correspondence (August-September 1888) between mine superintendent Charles Starrett and company officer Erastus D. Edgerton; and financial records (July-October 1888) including statements of expenses, payrolls, and invoices.

Records consist of stock certificates and stubs (October 1892-July 1894).

The Crevasse Mountain Mining Company was a Park County, Montana, mining operation. Officers included P.F. Barr, Erastus E. Edgerton, and John Edgerton. This collection (1890-1893) consists of general correspondence, financial records, legal documents, and superintendent reports on mine operations.

The Maginnis Mining Company was located in Maiden, Montana Territory, with offices in Helena headed by Samuel T. Hauser. Records consist of a payroll journal (October 1884-August 1889), including records for the Spotted Horse Mine.

This collection consists of records relating to hard rock mining impact plans in various areas, the most significant of the group the Stillwater Mining Company near Big Timber. Materials include correspondence, memoranda, reports, impact plans, minutes, financial documents, 35mm slides, news clippings, and legal filings. UPRS 184 B (91:3-7)