Cochise County Arizona Gold Production
The Turquoise (Courtland, Gleeson) mining district lies on the east side of the Dragoon Mountains, about 14 miles due east of Tombstone and about 18 miles north-northeast of Bisbee. During the 1880's mines near Gleeson produced oxidized ore rich in gold, silver, lead, and copper, and in 1901 mining of copper deposits near Courtland was started. Mixed oxide-sulfide ore was mined on a large scale from 1912 through 1918, but thereafter activity declined and remained at a low level through 1955. The district was idle from 1956 through 1959. Early gold production figures were not ascertained, but from 1908 through 1955 the district produced about 70,000 ounces.
The northwest-trending Dragoon Mountains are composed primarily of contorted and faulted Paleozoic sedimentary rocks and intrusive masses of monzonitic and granitic rocks of Triassic or Jurassic and Cretaceous or Tertiary age. The Paleozoic formations are the Bolsa Quartzite and Abrigo Limestone of Cambrian age, the Escabrosa Limestone of Mississippian age, the Horquilla Limestones of Pennsylvanian age, the Earp Formation of Late Pennsylvanian and Permian age, and the Colina Limestone and Epitaph Dolomite of Permian age (Gilluly, 1956, p. 14-49). In the interval between the end of the Paleozoic and the beginning of the Cretaceous the rocks were deformed and intruded by masses of Gleeson Quartz Monzonite, Copper Belle Monzonite Porphyry, and Turquoise Granite, all of Triassic or Jurassic age. The Sugarloaf Quartz Latite was probably intruded at the end of Cretaceous time. In early Tertiary time the rocks were displaced by strong northwest-trending thrust faults, and in Pliocene time normal faulting occurred which formed the major topographic features of the present (Gilluly, 1956, p. 159, 160).
The ore bodies are pyritic replacement deposits in limestone, shale, and porphyry along thrust faults. Some of the deposits are oxidized and consist of masses of iron and copper oxides containing cavities lined with chrysocolla, malachite, and azurite. The unoxidized deposits are mainly pyrite and chalcopyrite with local accumulations of bornite, sphalerite, and galena (Ransome, 1913). The gold occurs as very finely divided particles in all the ores; in the oxidized deposits some gold is contained in cerargyrite (Wilson, 1927, p. 39, 50).