ISS015-E-29867 (20 Sept. 2007) — Bingham Canyon Mine, Utah is featured in this image photographed by an Expedition 15 crewmember on the International Space Station. The Bingham Canyon Mine (center) located approximately 32 kilometers to the southeast of Salt Lake City, UT is one of the largest open-pit mines in the world, measuring over 4 kilometers wide and 1,200 meters deep. The mine exploits a porphyry copper, a type of geological structure formed by crystal-rich magma moving upwards through pre-existing rock layers. As the magma cools and crystallizes (forming an igneous rock with large crystals in a fine-grained matrix, known as a porphyry), hot fluids circulate through the magma and surrounding rocks via fractures. This process of hydrothermal alteration typically forms copper-bearing and other minerals in spatial patterns that a geologist recognizes as a potential porphyry copper deposit. Parallel benches (stepped terraces), visible along the western pit face (center left), range from 16 to 25 meters high – these provide access for equipment to work the rock face, as well as maintaining stability of the sloping pit walls. A dark, larger roadway is also visible directly below the benches. Brown to gray, flat topped hills of gangue (waste rock) surround the pit, and are thrown into sharp relief by shadows and the oblique viewing angle of this image. Leachate reservoirs associated with ore processing are visible to the south of the city of Bingham Canyon, UT (right).