This is a 2.1" long, natural formation of native copper. This specimen is an old collection piece that originally came from the New Cornelia Mine which is located in the Ajo Mining District of Arizona. When active, this open pit mine produced significant amounts of copper ore from 1916 - to the mid 1980's.
Native copper is an uncombined form of copper which occurs as a natural mineral. Copper is one of the few metallic elements to occur in native form, although it most commonly occurs in oxidized states and mixed with other elements. Native copper was an important ore of copper in historic times and was used by pre-historic peoples.
Native copper occurs rarely as isometric cubic and octahedral crystals, but more typically as irregular masses and fracture fillings. It has a reddish, orangish, and/or brownish color on fresh surfaces, but typically is weathered and coated with a green tarnish of copper carbonate.