This report summarizes mining practices of a large number of metal mines in the United States and foreign countries. The adaptation of mining methods best suited to the various natural conditions in mines is discussed, and comparative costs are presented. The basic data—gathered in the field by Bureau of Mines engineers and consultants in cooperation with mine operators—have been published in a series of information circulars dealing with practices and costs at individual mines and ore-dressing plants. The data have been made comparable by adhering to a standard form of presentation in the individual reports.
The first circular was issued, 250 dealing with mining and milling of metallic ores had been published. Of this number, 164 deal with operations at individual mines and plants—94 with mining only, 59 with milling only, and 11 with mining and milling. Eleven circulars are summaries, each covering a particular mining method, and 53 are discussions of separate operations involved in mine operation or deal with special phases of mining. Seven of them treat special ore-dressing and allied subjects, and 15 arc a part of a mineral-industries survey by counties or districts, in which many individual properties are described and costs and other data are presented. Earlier