Malachite

Malachite is a green, opaque mineral with the chemical formula Cu2CO3(OH)2, belonging to the copper carbonate hydroxide group. It typically forms in the monoclinic crystal system, appearing as botryoidal, fibrous, or stalagmitic masses within underground fractures and deep spaces where chemical precipitation occurs from hydrothermal fluids and the water table. While individual crystals are uncommon, they can occur as slender, needle-like prisms, and pseudomorphs after azurite crystals are also found.

The mineral’s name comes from the Greek word *molochites lithos*, meaning “mallow-green stone,” due to its resemblance to mallow leaves. This name passed through Latin, Middle French, and Middle English before becoming “malachite.” Its green color comes from copper (Cu2+). Mining of malachite dates back to at least 4000 BC near the Isthmus of Suez and Sinai. Around 3,800 years ago, it was extensively mined at the Great Orme Mines in Britain using stone and bone tools, with activity ending around 600 BC after producing up to 1,760 tonnes of copper. At Timna Valley in modern Israel, malachite has been mined and smelted for copper for over 3,000 years. It has since been used as both an ornamental stone and a gemstone.

The use of malachite and azurite as indicators for copper ore indirectly led to the naming of nickel. The mineral nickeline (also called niccolite) weathers into a green mineral (annabergite) that resembles malachite. This led to failed attempts to smelt nickeline for copper, as the high temperatures needed to reduce nickel made it impossible. In Germany, this deceptive ore was called *Kupfernickel*, meaning “copper demon.” Swedish alchemist Baron Axel Fredrik Cronstedt, trained by cobalt discoverer Georg Brandt, suspected a new metal in *Kupfernickel* and successfully smelted it in 1751, producing a silvery-white, iron-like metal previously unknown except in some meteorites. He named the new metal after the “nickel” part of *Kupfernickel*.

Malachite typically forms from the supergene weathering and oxidation of primary sulfidic copper ores, often alongside azurite, goethite, and calcite. Its properties are similar to azurite’s except for its vibrant green color, and the two minerals frequently occur together. Malachite is more common than azurite and is usually associated with copper deposits near limestone, which provides the carbonate source. Large quantities were mined in the Urals, Russia, though mining there had ceased by 2006, though new deposits may have been discovered. It is found worldwide, including in the Democratic Republic of the Congo, Gabon, Zambia, Namibia, Mexico, Australia, France, Israel, and the southwestern United States, especially Arizona. Historically, malachite was thought to be the main component of patina on copper and copper alloys exposed to open air, but sulfate and chloride from air pollution or sea winds usually produce brochantite or atacamite instead. Synthetic malachite, called basic copper carbonate or green verditer, can also be produced.

Malachite crystallizes in the monoclinic system, with a structure of alternating Cu2+ and OH− ions forming positively charged chains woven between isolated triangular CO32− ions. Each copper ion bonds to two hydroxyl ions and two carbonate ions; each hydroxyl bonds to two copper ions; and each carbonate bonds to six copper ions.

From antiquity until around 1800, malachite was used as a green pigment in paints. It is moderately lightfast, sensitive to acids, and varies in color, but has since been replaced by synthetic greens like verditer. For decorative purposes, malachite appears in the Malachite Room of the Hermitage Museum (featuring a large vase), the Malachite Room in Mexico City’s Castillo de Chapultepec, and in Russian tsars’ castles, paneling, and inlaid works. The Demidov Vase, now in the Metropolitan Museum of Art, and “The Tazza,” a large malachite vase given by Tsar Nicholas II and displayed at the Linda Hall Library, are notable examples. During the reign of Tsar Nicholas I, malachite decorative pieces were popular diplomatic gifts. In China, it was used as far back as the Eastern Zhou period. The base of the FIFA World Cup Trophy contains two layers of malachite.

A 17th-century Spanish superstition held that children wearing a malachite lozenge would sleep better and be protected from evil spirits. Marbodus recommended it as a talisman for young people due to its protective qualities and sleep aid. It was also historically worn for protection from lightning and contagious diseases, as well as for health, success, and constancy in affections. During the Middle Ages, it was worn engraved with a figure or symbol of the Sun.