The Bingham Canyon Mine, also known as the Kennecott Copper Mine, is an open-pit mining operation extracting a large porphyry copper deposit southwest of Salt Lake City, Utah, USA, in the Oquirrh Mountains. It is the deepest open-pit mine in the world. The mine is owned by Rio Tinto Group, an international mining and exploration company headquartered in the United Kingdom. The copper operations at Bingham Canyon Mine are managed through Kennecott Utah Copper Corporation which operates the mine, a concentrator plant, a smelter, and a refinery. The mine has been in production since 1906, and has resulted in the creation of a pit over 0.75 miles (1.2 km) deep, 2.5 miles (4 km) wide, and covering 1,900 acres (7.7 km²). According to Kennecott, it is the world’s largest man-made excavation. It was designated a National Historic Landmark in 1966 under the name Bingham Canyon Open Pit Copper Mine.
Cross-section through open pit, showing ore zonation, USGS.
The Bingham Canyon orebody is a porphyry copper deposit, formed by a quartz monzonite porphyry intruded into sedimentary rocks. It has the concentric alteration pattern and mineralogic zonation typical of porphyry copper deposits.
The oldest rocks at Bingham Canyon–sandstones, quartzites and limestones–were originally deposited as sediment by the shallow seas that covered the region 300 million years ago (in the late Paleozoic Era). Much later, between 60 and 135 million years ago, extensive folding and faulting of the sediments created the Oquirrh Mountains.
Geologic map showing bedrock geology and alteration zones, USGS.
Thirty to 40 million years ago, massive igneous intrusions initiated the process of mineralization. Extreme pressure forced superheated, mineral-rich solutions into fractured intrusive and adjacent sedimentary rock. Upon cooling, the mineralized solutions deposited enormous quantities of metals throughout a broad section of igneous and sedimentary rock that is now known as the Bingham Stock.
Bingham Canyon is not presently a source of notable mineral specimens. The Bingham Stock is a porphyry deposit, meaning that copper minerals—primarily chalcopyrite–are present in very low grades and disseminated throughout the granite-like host rock as tiny grains, seams and fracture coatings.
Over its life, Bingham Canyon has proven to be one of the world’s most productive mines. As of 2004, ore from the mine has yielded more than 17 million tons (15.4 Mt) of copper, 23 million ounces (715 t) of gold, 190 million ounces (5,900 t) of silver, and 850 million pounds (386 kt) of molybdenum. The value of the resources extracted from the Bingham Canyon Mine is greater than the Comstock Lode, Klondike, and California gold rush mining regions combined. Cumulatively, Bingham Canyon has produced more copper than any other mine in the USA, and is the second in the world after Chuquicamata in Chile. Mines in Chile, Indonesia, Arizona, and New Mexico now exceed Bingham Canyon’s annual production rate. High molybdenum prices in 2005 made the molybdenum produced at Bingham Canyon in that year worth even more than the copper. The value of metals produced in 2006 at Bingham Canyon was US$1.8 billion dollars.
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