Malachite

Formula: Cu2(CO3)(OH)2

Colour: Bright green, with crystals deeper shades of green, even very dark to nearly black; green to yellowish green in transmitted light.

Lustre: Silky, Earthy

Hardness: 3½ – 4

Specific Gravity: 3.6 – 4.05

Crystal System: Monoclinic

Member of: Rosasite Group.

Name: Named in antiquity (see Pliny the Elder, 79 CE) molochitus after the Greek μαλαχή, “mallows,” in allusion to the green color of the leaves. Known in the new spelling, malachites, at least by 1661.

Malachite is a green, very common secondary copper mineral with a widely variable habit. Typically it is found as crystalline aggregates or crusts, often banded in appearance, like agates. It is also often found as botryoidal clusters of radiating crystals, and as mammillary aggregates as well. Single crystals and clusters of distinguishable crystals are uncommon, but when found they are typically acicular to prismatic. It is also frequently found as a pseudomorph after Azurite crystals, which are generally more tabular in shape. The Cu analogue of chukanovite.