CuCO3-Cu(OH)2. An opaque green mineral composed of basic (hydrated) copper carbonate with pronounced, often concentric, banding. It has a Mhos hardness of 4. Malachite occurs naturally with the blue copper carbonate mineral called azurite with malachite being the more abundant of the two. Major deposits of the copper ores have been found in Siberia (Nizhne-Tagilsk), France (Chessy), Nambia (Tsumeb), and the U.S. (Bisbee, Arizona). Both malachite and azurite have been used as gemstones and paint pigments since before 3000 BCE. Malachite is prepared as a pigment by careful selection, grinding, washing and levigation. Coarsely ground malachite gives a dark green colour while finely ground particles give a lighter more transparent tone. Malachite is lightfast but is sensitive to acids and sulphur fumes. Basic copper carbonate can also be made artificially by colouring chalk with copper sulphate. The synthetic pigment, called green verditer, tends to have regularly sized particles with rounded edges. The colour is paler than malachite. It was rarely used in fine art paintings, but rather for both distemper and oil based interior house paints in the 19th century. It is listed among the pigments used for colouring stucco marble in the nineteenth and twentieth century. Synonyms: basic copper carbonate; basic cupric carbonate; green hydrous copper carbonate; green bice; Bremen green; green verditer; Hungarian green; mountain green; mineral green; copper green; iris green; Olympian green; Berggrün (Ger.); Malachit (Ger.); verdetto della Magna (It.); malachito (It.) malaquita (Sp.); malachite (Fr.); rokusho (Jap.); shih lü (Chin.). Wittenburg (1999); Museum of Fine Arts, Boston (2000); Trench (2000). [J. Cassar, R. de Angelis]