Open-pit copper mining methods

A former large-output surface Cu-Ag-Au-Mo-Zn-Ti-Nb-Rb-Gemstones mine located in the SE ¼ sec. 22, SW ¼ sec. 23, NW ¼ sec. 26 & the NE ¼ sec. 27, T. 12S., R.6W., about ½ mile (0.8 km) South of Ajo. Discovered by the Spaniards in 1750. First produced in modern times in 1917. Owned at times, or in part, by the Arizona Copper Mining & Trading Co.; St. Louis Copper Co.; the Rescue Copper Co.; Cornelia Copper Co.; New Cornelia Copper Co. (1912-1916); Calumet & Arizona Copper Co.; and the New Cornelia Division, Phelps Dodge Corp.



Mineralization is an elliptical ore body 2,011.63 meters long, 1,206.98 meters wide, 487.68 meters deep, and 304.8 meters thick, with veinlets and disseminations of chalcopyrite, bornite, and minor pyrite, oxidized in the upper part to carbonates, silicates, and minor chalcocite, deposited in fractured and faulted, altered Laramide quartz monzonite and bordering quartz diorite facies, and often in close association with irregular pegmatite zones in the intrusive.