Malachite’s most striking physical property is its green color. All specimens of the mineral are green and range from a pastel green, to a bright green, to an extremely dark green that is almost black. It is typically found as stalactites and botryoidal coatings on the surfaces of underground cavities – similar to the deposits of calcite found in caves. When these materials are cut into slabs and pieces, the sawn surfaces often exhibit banding and eyes that are similar to agate.

Malachite is rarely found as a crystal, but when found, the crystals are usually acicular to tabular in shape. The crystals are bright green in color, translucent, with a vitreous to adamantine luster. Non-crystalline specimens are opaque, usually with a dull to earthy luster.

Malachite is a copper mineral, and that gives malachite a high specific gravity that ranges from 3.6 to 4.0. This property is so striking for a green mineral that malachite is easy to identify. Malachite is one of a small number of green minerals that produces effervescence in contact with cold, dilute hydrochloric acid. It is also a soft mineral with a Mohs hardness of 3.5 to 4.0.

Physical Properties of Malachite
Chemical Classification	Carbonate
Color	Green
Streak	Green
Luster	Rare crystals are vitreous to adamantine. Fibrous specimens are silky. Massive specimens are dull to earthy. Polishes to a very bright luster.
Diaphaneity	Most specimens are opaque. Crystals are translucent.
Cleavage	Perfect in one direction. Fair in a second direction.
Mohs Hardness	3.5 to 4.0
Specific Gravity	3.6 to 4.0
Diagnostic Properties	Green color, soft, effervesces with dilute HCl to produce a green liquid.
Chemical Composition	Cu2(CO3)(OH)2
Crystal System	Monoclinic
Uses	A minor ore of copper. Gemstones, small sculptures, pigment.