MALACHITE & AZURITE
Malachite & azurite are attractive, richly colored copper hydroxy-carbonate minerals. Malachite has a nice green color - its formula is Cu2CO3(OH)2. Azurite has a dark, rich blue color - its formula, Cu3(CO3)2(OH)2, is very close to malachite. The blue color of azurite is from Cu+, while the green color of malachite is from Cu+2. Azurite & malachite almost invariably occur together, and are telling indicators of copper in the field, even in very small quantities. Blue azurite tends to crystallize first, and can convert to green malachite. Some azurite-malachite specimens are solid enough to be cut and polished as semi-precious stone.
Malachite & Azurite (7.5 cm across)
Botryoidal malachite (7.7 cm across) from Katanga Province, southern Zaire ("D.R. Congo").
Botryoidal malachite (3.9 cm across) from Milpillas, Sonora, Mexico.
Azurite from Shilu, Guangdong Province, China.
Azurite and malachite (above & below) acting as cement minerals in a breccia. From the Morenci Mine in Arizona, USA.