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 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.
Colors: Pale rose on fresh surface, quickly darkens to copper-red; in reflected light, pale rose. Tarnishes to black or green in air. Copper gives a deep blue coloration in the presence of ammonia ligands.
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