Malachite

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This article is about the mineral. For the butterfly see Malachite (butterfly)

Malachite
Image:Malachite Zaire.jpg
General
Category	Mineral
Chemical Formula	Cu₂CO₃(OH)₂
Identification
Crystal system	Monoclinic - prismatic
Crystal habit	Massive, botryoidal, stalactitic
Color	Green
Cleavage	Perfect
Fracture	Conchoidal to splintery
Mohs Scale of Hardness	3.5 - 4
Luster	Dull/vitreous in large quantities, silky in crystal form
Streak	green
Specific gravity	3.6 - 4

Image:MoreMalachite.jpg

Malachite is a carbonate mineral, copper(II) carbonate hydroxide Cu₂CO₃(OH)₂. It crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare, but do occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur.

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.

The stone's name derives (via Latin and French) from Greek molochitis, "mallow-green stone", from molochē, variant of malachē, "mallow". Malachite 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. It is also used for decorative purposes, such as in the Malachite Room in the Hermitage which features a huge malachite vase.