Malachit

Malachite is a copper carbonate hydroxide mineral with the chemical formula Cu2(CO3)(OH)2. It forms as a secondary mineral in the oxidized zones of copper-bearing ore deposits, developing from the weathering and alteration of primary copper sulfides such as chalcopyrite. Malachite commonly occurs as massive, botryoidal, or stalactitic deposits and exhibits characteristic green banding caused by variations in copper content and formation conditions. It is frequently found alongside azurite, chrysocolla, and cuprite.

Physical properties: Malachite is opaque with a silky to earthy luster and a bright to dark green color. It has a Mohs hardness of about 3.5 to 4 and a specific gravity around 3.6 to 4.0. The mineral shows a pale green streak and tends to break with a conchoidal to uneven fracture; it has one good cleavage direction. Crystals are uncommon; when present, malachite belongs to the monoclinic system.

Occurrence and localities: Important sources include copper districts in the Ural Mountains, the Democratic Republic of Congo (formerly Zaire), Namibia, Australia, and various locales in the United States such as Arizona and Nevada. It often forms in the same deposits as azurite.

Uses: Malachite is mined as a minor copper ore and is widely valued for ornamental purposes. It has been used as a gemstone and lapidary material, and as a pigment historically in green paints. It is typically processed to extract copper ore in some deposits, but in most cases is collected for its beauty rather than ore value.

Safety: Malachite can generate copper-containing dust that is toxic if inhaled. It should be handled with care, especially during grinding or cutting, and dust inhalation should be avoided.