Malachite
Kolwezi, Shaba Province, Zaire

This specimen of stalactitic malachite measures 22cm x 15cm x 11 cm. It was donated to the museum by Mr. Robert Sherrod in 1985.

Malachite Cu₂CO₃(OH)₂

Carbonates; basic copper carbonate

Color and Luster: Emerald-green, grass-green, dark green; adamantine, silky, dull; streak light green

Hardness: 3.5-4

Cleavage: Perfect, one direction crosswise

Fracture: Conchoidal, splintery

Crystals: Monoclinic; crystals rare and usually short or long prismatic; also radial, fibrous, botryoidal, stalactitic, incrusting, earthy

Malachite is a common secondary mineral of copper bearing deposits. It may form as small acicular crystals but more commonly occurs as botryoidal or stalactitic masses. Nicely patterned, massive malachite is highly prized as ornamental or gem material, used for carvings and cabochons.

Photo by Mary Sutherland

Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals