Basic copper carbonate. It is an ore of copper.
Crystal system Monociinic.

Appearance It occurs as rounded (mamillated) masses or encrustations, consisting of radiating or parallel aggregates of minute elongated crystals. It has striking color stratification from quite bright to dark green. The stratifications are curved according to the outer surface of the mass. It is opaque or semiopaque.

Physical properties It has a low hardness of about 4,
like other carbonates. The refractive indices are nx 1 .655. ny 1.909, but are difficult to establish, both because the material is semiopaque, and because ny is very high, well above the range of ordinary retractometers. It has a density of about 3.3 g/cm.

Genesis It is commonly formed by the action of atmospheric agents on copper mineral outcrops.

Occurrence Large quantities of malachite are found wherever copper outcrops occur: in Chile, the United States, Zaire, Zimbabwe, Namibia. the Soviet Union, and Australia. But it is found almost everywhere in the form of small encrustations, together with azurite.

Malachite
The name is derived from the Greek malakhe, meaning "mallow," evidently because of the color.

Appearance The color is always green, varying from a mid green which can be described as mallow green, to a very dark, even blackish green. These tones appear, as a rule, in alternate stripes (transverse to the length ot the crystal, which are obviously successive layers of concretion and have an arrangement similar to that of the veins in other concretions, with broad curves, dome shapes, and undulations, generally following the direction of the outer surface of the stone. it has a fairly low hardness, but can acquire exceptional {though not very durable) polish. It is easily damaged by acids. Large blocks are used for slabs. balusters. and other sculpted objects. It is also employed for mosaics, boxes, figurines, cabochons. and beads.

Distinctive features The green color, veining, shape of the veins, and polish make it unmistakable.

Occurrence In the past, most malachite came from the Soviet Union (Urals), but nowadays large quantities are also obtained from Zaire, Zimbabwe, Namibia, Chile, the United States, and Australia.

Value It is not often used as a gem and has a very low value. It is much admired, however, as an ornamental material and is quite highly priced tor its category. especially when the attractiveness of the material is matched by fine workmanship.

Simulants and synthetics It has not been imitated and is not produced synthetically.