Native Copper
Keweenaw Peninsula, Michigan
This specimen measures 11.5cm x 7cm
Copper Cu
Native Elements; often with small amounts of arsenic, antimony, bismuth, iron, and silver
Color and Luster: Copper-red; tarnish black, blue, green; metallic; streak copper-red, shiny
Hardness: 2.5-3
Cleavage: None
Fracture: Hackly; ductile and malleable
Crystals: Isometric; usually form cubic and dodecahedral, rarely octahedral; often flattened, elongated, distorted; also scales, plates, lumps, branching aggregates
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals