Morenci Mine (Morenci pit; Phelps Dodge Morenci Mine; Morenci-Metcalf), Morenci, Copper Mountain District (Clifton-Morenci District), Shannon Mts, Greenlee Co., Arizona, USA
|Latitude & Longitude (WGS84):||33° 5' 26'' North , 109° 21' 58'' West|
|Latitude & Longitude (decimal):||33.0905555556, -109.366111111|
|Other regions containing this locality:||Sonoran Desert, North America|
An open pit and underground Cu-Mo-Au-Ag-Pb-Zn-U-Re-REE-Gemstone-Gypsum-Talc/soapstone-garnet mine located in secs. 8, 9, 15, 17 and in the N½ sec. 16, T4S, R29E (Clifton 15 minute topo map), at Morenci, 4.5 miles NW of Clifton. First produced 1942. Owned by Phelps Dodge Corp.
Mineralization is an elliptically shaped ore body in a porphyry copper-molybdenum deposit. The ore zone is 1341.12 meters long, 853.44 meters wide with a depth to top of 76.2 meters and a depth to bottom of 701.04 meters, and a thickness of 259.08 meters, and plunges E. Ore control was NE-trending fisures, veining, and crackling. Ore concentration was complex as progressively more silicic intrusions carried sulfide phases into fractures created by older pulses. Alteration was hydrothermal with kaolinization, sericitization, calc-silicate or pelitic hornfels and skarn.
The district is zoned with a chalcopyrite-rich core surrounded by a pyrite envelope which is surrounded by protore. Ag and Au are more abundant in less altered areas. The greatest Mo concentrations are in granite porphyry, less in Precambrian Granite.
The enrichment blanket ranges from 50 to 1000 feet thick and thickens from W to E. Turquoise found in the oxidized part of the deposit. Massive andradite is found in a skarn deposit at the southwest corner of the large open pit.
Area structures include the NW-trending Copper Mountain Fault, which dsplaces enrichment blanket 200 feet. Also NE-trending fissures may have localized porphyry emplacement.
The workings are 2133.6 meters long and 1219.2 meters wide. The open pit work started in 1937. Molybdenite runs 400 to 2000 ppm of Re.
Mineral ListMineral list contains entries from the region specified including sub-localities
|Pliocene - Miocene2.588 - 23.03 Ma||Miocene-Pliocene volcanic rocks|
May include hypabyssal intrusions.
|Paleocene - Late Cretaceous56 - 100.5 Ma||Early Tertiary to Late Cretaceous granitic rocks|
Porphyritic to equigranular granite to diorite emplaced during the Laramide orogeny. Larger plutons are characteristically medium-grained, biotite +/- hornblende granodiorite to granite. Smaller, shallow-level intrusions are typically porphyritic. Most of the large copper deposits in Arizona are associated with porphyritic granitic rocks of this unit, and are thus named 'porphyry copper deposits'. (50-82 Ma)
|Mississippian - Cambrian323.2 - 541 Ma||Cambrian-Mississippian sedimentary|
References for regional geology:
Data provided by Macrostrat.org
Garrity, C.P., and Soller, D.R.,. Database of the Geologic Map of North America: adapted from the map by J.C. Reed, Jr. and others (2005). U.S. Geological Survey Data Series 424 .
USGS compilers. State geologic map data. State Maps.
Geological Survey of Canada. Generalized geological map of the world and linked databases. doi:10.4095/195142. Open File 2915d.
73 valid minerals.
Localities in this Region
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;
Guild, F.N. (1910), The Mineralogy of Arizona, The Chemical Publishing Co., Easton, PA.
University of Arizona Bull. 41 (1916-17), Mineralogy of Useful Minerals in Arizona: 50.
Butler, B.S. & Wilson E.D. (1938), Arizona Bureau of Mines Bull. 145: 72-80.
Moolick, R.T. & J.J. Durek (1966), The Morenci district, in S.R. Titley and C.L. Hicks (editors), Geology of the porphyry copper deposits, southwestern North America, Universty of Arizona Press, Tucson: 221-231.
Langton, J.M. (1973), Ore Genesis in the Morenci-Metcalf District, A.I.M.E. Transactions: 254: 247-257.
Paydirt (1981) Phelps Dodge, A Copper Centennial, 1881-1981.
Engineering and Mining Journal (1987) Phelps Dodge Has Something to Smile About, August, 1987: 24-31.
Phillips, K.A. (1987), Arizona Industrial Minerals, 2nd. Edition, Arizona Department of Mines & Minerals Mineral Report 4, 185 pp.
Minerals Yearbook (1988) - Mining & Quarrying Trends: 31;
Peirce, H. Wesley (1990), Arizona Geological Survey Industrial Minerals card file.
Phillips, et al (1990).
Walenga, Karen (1990) SX-EW Production Doubled to 200 Million PPY, Southwestern Pay Dirt, 4/90: 4A-6A.
Dillard, Gary (1991) Four Major Orebodies will Shoulder the Load. Southwestern Pay Dirt, 11/91: 4A-14A.
Epler, Bill (1991) Phelps Dodge Finds 150 Million More Tons of Ore at Morenci. Southwestern Pay Dirt, 1/91: 3A.
Epler, Bill (1991) Phelps Dodge Relocates Highway at Morenci Mine. Southwestern Pay Dirt, 7/91: 4A-6A.
Blair, G. (1992), The Rockhound's Guide to Arizona: Helena, MT, Falcon Press.
Carter, Russell A. (1992) Expansion Almost Complete at Arizona’s Mission and Morenci Mines. Engineering and Mining Journal, 2/92: C14-C16.
Niemuth, N.J. & K.A. Phillips (1992), Copper Oxide Resources, Arizona Department of Mines & Mineral Resources Open File Report 92-10: 8 (Table 1).
Dillard, Gary (1994) Phelps Dodge is Contemplating SX-EW Expansion at Morenci. Southwestern Pay Dirt, 5/94: 3A, 8A.
Snider, T.R. (1994) Morenci Southside will Add 150 million pounds of Cathode. Southwestern Pay Dirt, 8/94: 3A.
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 124, 125, 163, 166, 193, 198, 233, 261, 292, 314, 345, 368, 388.
Merritt Stephen Enders (2000) The Evolution of Supergene Enrichment in the Morenci Porphyry Copper Deposit, Greenlee County, Arizona. PhD Thesis, University of Arizona
Singer, D.A., Berger, V.I., and Moring, B.C. (2005): Porphyry Copper Deposits of the World: Database, Map, and Grade and Tonnage Models. USGS Open-File Report 05-1060.
Grant, Raymond W., Richard A. Bideaux & Sidney A. Williams (2006), Minerals Added to the Arizona List 1995 to 2005: 1.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10027138, MRDS ID #M002216; and file ID #10282444.
U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0040110018.