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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.
The hunt for strategic metals from large volume, low-grade deposits involved Bureau geologists in research and design of ore concentrating facilities at five major low-grade copper deposits. Following World War II, renewed emphasis on geologic mapping led to the publication of county geologic maps between 1957 and 1960.
Resolution Copper (RCM) is a joint venture owned by Rio Tinto and BHP formed to develop and operate an underground copper mine near Superior, Arizona, U.S. The project targets a deep-seated porphyry copper deposit located under the now inactive Magma Mine .
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]
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 byproducts. [2] Byproduct molybdenum from copper mining makes Arizona the nation's ...
Phyllic alteration typically forms in the base-metal zone of a porphyry system. [2] Alteration assemblages vary with depth and with degree of fluid interaction. In deep environments, the most highly altered areas are veins and thin selvages, or halos, that surround them. The selvages are generally <10 cm in diameter and composed of major ...
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]