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Porphyry copper deposits represent an important resource and the dominant source of copper that is mined today to satisfy global demand. [6] Via compilation of geological data, it has been found that the majority of porphyry deposits are Phanerozoic in age and were emplaced at depths of approximately 1 to 6 kilometres with vertical thicknesses on average of 2 kilometres. [6]
Arizona is known as the Copper State because it produces two-thirds of US copper annually. Laramide copper porphyry deposits are common around Tucson and include the Twin Buttes, Sierrita-Esperanza, Rosemont, Silver Bell and Mission-Pima mines, as well as the historical Ajo mine to the west.
It is commonly seen in copper porphyry ore deposits in calc-alkaline rocks. Phyllic alteration is characterised by the assemblage of quartz + sericite + pyrite, and occurs at high temperatures and moderately acidic (low pH) conditions. [1] Hydrogen-ion metasomatism is the process that causes phyllic alteration
This is common in porphyry copper and porphyry molybdenum deposits. Argillic alteration, commonly present in the distal areas of porphyry deposits, is a low-temperature assemblage that converts feldspars and some other minerals into clay minerals such as kaolinite and illite. It can overprint older, higher-temperature alteration assemblages. [13]
Gila County, Arizona: Freeport-McMoRan: Copper ore, leached 5 (2021) [2] 18 Carlota Gila County, Arizona: KGHM Polska Miedź: Porphyry copper open pit, producing copper cathode 3.2 (2018) [10] 19 Pumpkin Hollow (see Anaconda) Lyon County, Nevada: Nevada Copper IOCG skarn, underground, producing copper concentrate - (2019) [11]
The Safford Mine is an open-pit copper mine located in Graham County, Arizona, eight miles (13 km) north of the city of Safford. The mine is owned and operated by Freeport-McMoran Copper & Gold. Construction on the Safford mine began in mid-2006. Production began December 26, 2007, with full production starting in 2008. [1]
Mineral alteration refers to the various natural processes that alter a mineral's chemical composition or crystallography. [1]Mineral alteration is essentially governed by the laws of thermodynamics related to energy conservation, relevant to environmental conditions, often in presence of catalysts, the most common and influential being water (H 2 O).
In Arizona, copper mining has been a major industry since the 19th century. In 2007, Arizona was the leading copper-producing state in the country, producing 750 thousand metric tons of copper, valued at $5.54 billion. Arizona's copper production was 60% of the total for the United States. Copper mining also produces gold and silver as ...