Copper | |
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General | |
Category | Native metal |
Formula (repeating unit) | Cu |
Strunz classification | 01.AA.05 |
Dana classification | 1.1.1.3 |
Crystal system | Cubic |
Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
Space group | Fm3m |
Unit cell | a = 3.615 Å; Z = 4 |
Identification | |
Color | Pale rose on fresh surface, quickly darkens to copper-red; in reflected light, pale rose |
Crystal habit | As cubes, dodecahedra, and as tetrahexahedra; rarely as octahedra and complex combinations. Commonly flattened on {111}, elongated along [001]. Also as irregular distortions, in twisted, wirelike shapes; filiform, arborescent, massive |
Twinning | On {111} to produce simple contact and penetration twins and cyclic groups |
Cleavage | None |
Fracture | Hackly - jagged |
Tenacity | Highly malleable and ductile |
Mohs scale hardness | 2+1⁄2–3 |
Luster | Metallic |
Streak | Copper-red |
Diaphaneity | Opaque |
Specific gravity | 8.95 |
Solubility | Soluble in nitric acid |
Other characteristics | Tarnishes to black or green in air. |
References | [1][2][3][4] |
Native copper is an uncombined form of copper that 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.