AzuriteCopper Mountain Mine, Morenci, Copper Mountain District, Shannon Mts, Greenlee Co., Arizona, USA
Photo: Brhounds Latitude: 33°4'32"N
Longitude: 109°22'4"W
A former surface and underground Cu-Zn mine located in the SE¼SW¼SW¼SE¼ sec. 16, T4S, R29E, SW of the Humboldt shaft, SE of the Arizona Central shaft, under the present town of Morenci, on private land. Discovered in 1872 by W.L. Ryerson, John Swisshelm, Jim Bullard and Joe Yankie. Produced 1882-1920. Owned and operated by the Phelps Dodge Corp., Morenci Branch (1917-____). Past owners included the Detroit Copper Mining Co. of Arizona. The Copper Mountain Mine opens onto the Arizona Central vein and onto several irregular carbonate deposits in limestone. The Manganese Blue ore body and shaft are also located on the Copper Mountain claim; the Copper Mountain Mine tunnel extends onto the Arizona Central claim.
Mineralization is an irregular ore body hosted in the Longfellow Limestone. The ore zone has a depth to top of 30.48 meters and a depth to bottom of 121.92 meters, striking N15E and dipping 70SE. An associated rock unit is the Morenci Granite Porphyry. Ore control was NE-trending fissure veins containing an enormous deposit of low-grade chalcocite ore, changing to poor primary sulfides at varying depth. Ore concentration was extensive surface leaching on the downthrow side of the Copper Mountain fault to depths of 200 feet. Secondary enrichment of chalcocite ore about 300 feet deep. Alteration is oxidation to greatly varying depths. Chalcocite coats large bodies of sericitized porphyry containing disseminated pyrite.
Intergrowths of magnetite, pyrite, sphalerite, and chalcopyrite are irregularly distributed in the carbonates. The chalcocite ore body is usually considered to be a part of the Humboldt lode or an extension of the Wellington vein. The Copper Mountain claim has only a few central veins or seams, unlike the other great ore bodies of Copper Mountain.
Area structures include the Copper Mountain fault, which separates rich, disseminated chalcocite ore from barren porphyry. Cuprite and copper carbonates occur, associated with a small mass of limestone embedded in porphyry, on the boundary between the Copper Mountain and Humboldt Mines. South of the main adit is a rich, well-defined chalcocite seam about 14 inches wide. The ore bodies are contained between two porphyry dikes about 400 to 500 fet apart (Joy Dike and the Hummingbird Dike).
Tectonic component is the complex Copper Mountain fault system with substantial vertical displacement. Fault blocks generally downthrown to the NE.
Workings total 304.8 meters long and 152.4 meters deep. Developments included a 1000 foot tunnel that runs to the NW, 500 feet below the western crest of Copper Mountain, in the Arizona Central claim. Several stopes in the Copper Mountain and Blue Manganese lodes, reaching 100 feet in width; extensive drifting along veins. Production data included in Detroit Copper Co. mines; other Detroit Copper Co. mines are the Arizona Central, Manganese Blue, Ryerson, Yankie, and Montezuma mines.
References
Kunz, G.F. (1885), On remarkable copper minerals from Arizona, Annals of the New York Academy of Science: 3: 275-278.
Genth, F.A. (1890), Contributions to Mineralogy, American Journal of Science: 40: 114.
Farrington, O.C. (1891), On crystallized azurite from Arizona, American Journal of Science: 41: 300-307.
Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 1094.
Lindgren, W. (1903), The copper deposits of Clifton, Arizona, Engineering and Mining Journal: 75: 705.
Lindgren, W. (1904), The genesis of copper deposits, Engineering and Mining Journal: 78: 987.
Lindgren, W. (1905), The copper deposits of the Clifton-Morenci district, Arizona, USGS PP 43: 212, 276-278.
Stevens, P. (1911) The Copper Handbook: Vol. X: 734-735, Detroit Copper Mining Co. of Arizona.
Reber, Jr., L.E. (1916), The mineralization at Clifton-Morenci, Economic Geolgy: 11: 528-573.
University of Arizona Bull. 41 (1916-17), Mineralogy of Useful Minerals in Arizona: 23, 40, 44.
Schwartz, G.M. (1934), Paragenesis of the oxidized ores of copper, Economic Geology: 29: 55-75.
Grout, F.E. (1946), Microscopic characters of vein carbonates, Economic Geology: 41: 475-502.
Watt, Roberta (1956) History of Morenci, Arizona. M.A. thesis, University of Arizona.
Galbraith, F.W. & D.J. Brennan (1959), Minerals of AZ: 39, 55, 108.
Bideaux, R.A. (1973), The collector (on azurite), Mineralogical Record: 4: 34-35.
Bennett (1975) Geology and Origin of the Breccias in the Morenci-Metcalf District, Greenlee County, Arizona, MS thesis, University of Arizona, 153 pp.
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 125, 198, 246, 266, 284, 286.
Arizona Bureau of Mines Bull. 149, No. 15.
U.S. Bureau of Mines - Arizona Bureau of Geology and Mining Technology production file data.
U.S. Bureau of Land Management Mining District Sheet #840.
MRDS database Dep. ID #10088902, MRDS ID #M800424; and Dep. ID #10104152, MRDS ID #M800423.
Mineral List
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