Copper Mines in Arizona - USA - Open pit Copper mines - Arizona: Three open-air...

Copper Mines in Arizona - USA - Open pit Copper mines - Arizona: Three open-air copper mines near the city of Green Valley in Arizona. Image taken from the International Space Station (ISS) on January 14, 2010. This astronaut photograph illustrates three open-pit mines located west-northwest of the town of Green Valley, Arizona. While the mines appear to be close to each other, each exploits a separate porphyry copper deposit. The mine pits are recognizable by the concentric lines of benches cut into the pit sides. The benches allow equipment and personnel access to the fresh ore (gray) exposed at the bottom of the excavation. Water may also pool at the bottom of inactive pits, such as in the Twin Buttes Mine at image upper right (black areas). The open pit areas are surrounded by an array of sculpted tailings ponds and mine dump areas; these receive mine waste rock for storage and later leaching for further recovery of metals. The green color of the water in the tailings pond at image right is likely due to the presence of leached metals. The Asarco-Mission complex (image left) is an active producer of copper and molybdenum (important in making steel and other metal alloys), processing approximately 53,700 tons of ore per day (as of 2008). The Twin Buttes Mine (image top right), also a producer of copper and molybdenum, was closed in 1994 but was recently purchased by a new owner (Freeport-McMoran Copper & Gold) and may reopen. The Sierrita Mine at image lower right (also owned by Freeport-McMoran Copper & Gold) produces copper, molybdenum, and the rare metal rhenium. Rhenium is used to make high-temperature alloys for jet engine parts and in high-octane, lead-free gasoline. This mine can process over 115,000 tons of ore per day (as of 2007). Astronaut photograph was acquired on January 14, 2010 from the International Space Station (ISS)