This metal has been mined for thousands of years. Copper has a very high thermal and electrical conductivity. Pure copper is soft and has a reddish-orange color. Most copper is mined from large, open-pit mines. Chile is the top mine producer of the metal, followed by the U.S. Copper is used in electrical wires, plumbing, roofing, and various industrial uses in machines. In many instances, copper is used in place of aluminum because it is a better electrical conductor. Since it is waterproof, it has been used as roofing material. The green color of copper occurs when it is oxidized over a long period of time.