University of Arizona

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Records of the Commonwealth Mine


The Commonwealth Mine of Cochise County was discovered by John Pearce in 1895. Later that year he formed a partnership with John Brockman, R.A.F. Penrose, and D.M. Barringer and organized Commonwealth Mining and Milling Company. By 1905, the high-grade ore had played out and the shaft collapsed. The mine was purchased by Montana Tonopah Mines Company in 1910. The later records seem to indicate that the mine was controlled by the Commonwealth Owners. During its forty year existence, the mine produced $8 million worth of silver and $2.5 million in gold at a time when silver was priced around 50 cents an ounce, and gold was $20 an ounce.

The bulk of the Commonwealth Mine records document its activities from 1910 until 1930. Many records were destroyed in a fire and many of the remaining records are fragile and fragmentary. These remaining records best characterize the daily operations of the mine and its managers between 1910 and 1930. The broad themes of this collection outline the managerial and financial skills which kept the mine operating. 


The managers correspondence highlights the business acumen and legal matters. There are also several subject files, titled Automobiles, Cyanide, and Insurance which may represent the original filing systems used in the office. The financial files are mainly monthly account statements designating debits and credits for the company which outline the cash flow of the mine and its operational status. The legal files consist largely of contracts, agreements, and deeds relating to structural improvements at the mine, railroad right-of ways, leasing operations, smelting arrangements, equipment purchases, and mining claims. The tax files consist of annual and monthly reporting forms from the mine to the federal, state, and county offices. 

The directors of the Commonwealth Mine ventured into several other businesses in Pearce and the nearby communities. Fragments of records pertaining to the B.S.B. Egg Farm, Coronado Cattle Company, Glenn Land and Cattle Company, Midwest Sugar Company, and Worlds Fair Mine are present. A.Y. Smith was active on the Cochise County Highway Commission in 1919. The files contain minutes, reports, and correspondence of the Commission relating to a $1 million bond issue to construct and repair various roads in Cochise County.