Malachite
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Malachite is a carbonate mineral, copper(II) carbonate hydroxide Cu2CO3(OH)2. Malachite has a hardness between 3.5 and 4. It crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagtitic masses.
Malachite often results from weathering of copper ores and is often found together with azurite (Cu3(CO3)2(OH)2), goethite, and calcite. Except for the iridescent green colour, the properties of malachite are very similar to those of azurite and aggregates of the two minerals together are frequently found, although malachite is more common than azurite. Typically associated with copper deposits associated with limestones, the source of the carbonate.
It was used as a mineral pigment in green paints from antiquity until about 1800. The pigment is moderately lightfast, very sensitive to acids and varying in colour. The natural form was being replaced by its synthetic form, verditer amongst other synthetic greens.
Large quantities of malachite have been mined in the Urals. It is found in the Democratic Republic of Congo; Tsumeb, Namibia; Ural mountains, Russia; Mexico; Broken Hill, New South Wales; England; Lyon; and in the Southwestern United States especially in Arizona at Bisbee and Morenci.
References
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0471805807
- Mineral Galleries (http://mineral.galleries.com/minerals/carbonat/malachit/malachit.htm)
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