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):||33.09056,-109.36611|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||Csb : Warm-summer Mediterranean climate|
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
74 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
2.588 - 5.333 Ma
|Cenozoic volcanic rocks|
Age: Pliocene (2.588 - 5.333 Ma)
Lithology: Volcanic rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
|Ypresian - Campanian|
47.8 - 83.6 Ma
|Early Tertiary to Late Cretaceous granitic rocks|
Age: Phanerozoic (47.8 - 83.6 Ma)
Description: 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)
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.