Native Copper

Inhalt "Native Copper":

High Quality Content by WIKIPEDIA articles! Copper, as native copper, is one of the few metallic elements to occur in uncombined form as a natural mineral, although 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 as rarely 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(II) carbonate (also known as patina or verdigris). Its specific gravity is 8.9 and its hardness is 2.5-3.The mines of the Keweenaw native copper deposits of Upper Michigan were major copper producers in the 19th and early 20th centuries, and are the largest deposits of native copper in the world.