Basic copper carbonate. It is an ore of copper.
It occurs as rounded (mamillated) maws or encrustations, consisting of radiating or parallel aggregates of minute elongated crystals. It has striking stratification from quite bright to dark green. The stratifications are curved according to the outer surface of the mass. It is opaque or semiopaque.
It has a low hardness of about 4. like other carbonates. The refractive indices are n 1.655 fly 1.909, but are difficult to establish, both because the material is semiopaque, and because fly is very high, well above the range of ordinary refractometers. It has a density of about 3.8 g/cm.
It is commonly formed by the action of atmospheric agents on copper mineral outcrops.
Large quantities of malachite are found wherever copper outcrops occur: in Chile, the United States, Zaire, Zimbabwe, Namibia, the Soviet Union, are Australia. But it is found almost everywhere in the form of small encrustations, together with azurite.
The name is derived from the Greek matakhe, meaning "mallow," evidently because of the color.
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 of the crystal), which are obviously successive layers of cometion 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 a 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.
The green color, veining, shape of the veins, and polish make it unmistakable.
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.
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 for 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.
Writer – Curzio Cipriani and Alessandro Borelli