Malachite is a mineral with a hardness of 4 out of 10 on the Mohs scale of mineral hardness [?]. These Monoclinicly structured gems are made of copper hydroxycarbonate, their full chemical compound being Cu2(OH)2CO3.
Malachite is a bright green, basic copper carbonate.
It appears as fibrous, radiating aggregates with silky to dull luster, and its crystals are adamantine. Acicular crystals are common. It commonly occurs as a green film on other copper minerals and as botryoidal or reniform masses with concretionary, banded structure and emerald green color.
The color of the glassy, lustrous crystals is dark green, but in massive aggregates it varies in the individual layers from a luminous, sometimes bluish green to a dark, blackish green. These tones appear in alternate stripes (transverse to the length of 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 is semi-hard, heavy, fragile, and has good cleavage. It is semi-opaque, or translucent with vitreous to silky luster. It is soluble in concentrated acids, with effervescence. In hydrochloric acid it turns the solution green. When heated, it thoroughly loses water and turns black, then fuses fairly easily, coloring the flame green (copper).
It occurs widespread in the oxidized zone of copper deposits as a secondary mineral, produced by the reaction of sulfides with carbonate gangue. It is associated with azurite, cuprite, native copper, limonite and chrysocolla. It sometimes occurs in large masses with a core of azurite, also found disseminated in sandstones deposited by meteoric waters.
Pseudomorphs of malachite after azurite are common. It is also seen as a pseudomorph after cuprite in Chessy, near Lyon (France), and Ojanga (Namibia). Also after tennantite at Bieber, Hessen, and calcite, azurite, and cerussite at Tsumeb (Namibia).
Deposits were found in large masses in the Shaba (formerly Katanga) province (Zaire); Demidoff Mine, Nizhne-Tagilisk and Sverdlovsk (Russia). Good crystals can be found at Betzdorf (Germany), Chessy (France), Tsumeb (Namibia), Redruth, Cornwall (England), and above all in Copper Queen Mine, Bisbee, Arizona (USA). It is fairly rare in Italy, with compact masses on Elba and acicular crystals in Sardinia (Arenas, Sa Duchessa, Campo Posano).
During the last century enormous blocks weighing many kilos were extracted from iron-rich clay in mines in the Urals (Mednoroudianskoy and Goumechevskoy, Russia). They are almost legendary, because of their enchanting beauty. A giant mass was found in the early 1820's which produced about 250 tons of the finest cutting quality malachite.
Malachite is known as green copper carbonate, in contrast to azurite, known as blue copper carbonate.
Malachite is named after the Greek "malche" or "moloche," meaning "mallow," as it is similar in color to a mallow leaf.
Malachite was popular among the ancient Greeks and Romans. According to Pliny (77 A.D.) "molochitis," an opaque and saturated green colored mineral, was useful for cleaning wounds when burned, pulverized, and mixed with oil and wax. It was used in the Middle Ages as an emetic, and for the treatment of colic, in ancient Egypt as cosmetic and eye shadow.
It later became fashionable in the courts of the Russian Czars. The magnificent columns of St. Isaac's Cathedral, countless tables and urns in the Hermitage, and the hall facings of the winter Palace (Leningrad, Russia), are made of malachite.
The cutting plants of Leningrad produced many works of art in malachite, often given as tokens of friendship by the Czars to other princes.
The localities in the Ural Mountains have since been shut down. What remains is the Russian legend that anyone who drinks from a malachite goblet will understand the language of animals.
Malachite has long been prized as a semi-precious stone. Beautiful ornaments and table tops are made from banded forms of malachite. It is extremely decorative when cut into flat pieces and polished, due to the variegated color banding in various shades of green.
Large blocks are used for slabs, balusters, and sculpted objects, while smaller pieces are used for mosaics, boxes, figurines, cabochons, and beads.
Crushed malachite has been used as an inorganic pigment (mountain green).
Malachite is also a copper ore, and of interest to scientists and collectors.
It is still a coveted material for jewelry and artistic sculptures. The finest gem-quality malachite now comes from Kolwezi, Shaba (Zaire) and also from Mkubwa (Zambia).
Though it has very low value as a gem, it is highly-valued and priced when the attractiveness of the material is matched by fine workmanship. It has not been imitated and is not produced synthetically.