Malachite is a copper carbonate mineral known for its opaque green color and bands of light and dark green that curve through the stone like contour lines. It is soft (3.5 to 4 on the Mohs scale), so it works best in pendants, earrings, beads and carvings. People have used it as a pigment, a cosmetic and an ornamental stone for thousands of years.
What malachite is
Malachite has the formula Cu2CO3(OH)2. Copper is part of its chemistry, which makes it an idiochromatic mineral: the green comes from the mineral itself and does not depend on a trace impurity. Every piece of malachite is some shade of green, from pale mint to a green so dark it looks almost black.
Single crystals are rare and usually tiny needles. Almost all gem malachite is massive, built from countless fine fibers packed together. These aggregates often grow in rounded, grape-like masses that mineralogists call botryoidal, and in stalactites that form in open cavities. The crystal habit explains the look of the polished stone. When a lapidary slices across a botryoidal mass, the growth layers show up as concentric rings, often called bull's-eyes. A cut along the length of a stalactite shows parallel stripes instead.
The fibrous structure also gives polished malachite a silky sheen. Some pieces show a faint chatoyant shimmer when the fibers run parallel.
How and where it forms
Malachite is a copper ore mineral that forms near the surface. Rainwater and groundwater seep into copper deposits and react with copper sulfide minerals. The dissolved copper then meets carbonate from limestone or other rock, and malachite precipitates in cracks and cavities. Geologists call this the oxidized zone of a copper deposit. The same weathered zone produces turquoise, azurite and chrysocolla, and the page on sedimentary rocks and gemstones covers this kind of near-surface mineral growth.
Because malachite follows copper, its sources map onto the world's copper districts:
- The Katanga copper belt in the Democratic Republic of the Congo has been the main source of malachite for jewelry and carving since the 20th century. Zambia, on the same belt, also produces it.
- The Ural Mountains of Russia were the great source of the 18th and 19th centuries. Mines near Nizhny Tagil and Yekaterinburg produced huge solid masses.
- Arizona copper mines, Bisbee among them, have produced fine specimens, often mixed with azurite.
- Australia, Namibia, Mexico and China have also yielded gem and specimen material.
Azurite-malachite and other combinations
Azurite is a closely related copper carbonate with a deep blue color and the formula Cu3(CO3)2(OH)2. The two often grow side by side. Azurite holds less water in its structure, and over time it can alter into malachite. Some specimens show blue azurite crystals partly or fully replaced by green malachite that keeps the original crystal shape.
Lapidaries cut the mixed material as azurite-malachite, a blue and green stone that shows both minerals in one cabochon. Malachite also appears with blue-green chrysocolla, and in Arizona with turquoise. These mixtures share malachite's softness and need the same gentle handling.
Malachite in history
Ancient Egyptians mined malachite in the Sinai and the Eastern Desert. They ground it into a green pigment for paint and used it as eye makeup. European painters later used ground malachite as a green pigment until synthetic greens replaced it in the 19th century. The name comes from the Greek word for the mallow plant, a reference to the green of its leaves.
Russia made malachite famous as a decorative stone. Workshops in the Urals and St. Petersburg developed a technique now called Russian mosaic. Workers sawed malachite into thin slices, then fitted the pieces over a stone or metal base so the bands matched across the joins. The finished surface looked like one enormous block. This method stretched the supply of good material and made very large objects possible.
The best-known result is the Malachite Room in the Winter Palace, now part of the State Hermitage Museum in St. Petersburg. Architect Alexander Bryullov designed it after a fire gutted the palace in 1837. Its columns, pilasters, fireplace and vases are faced with Ural malachite in Russian mosaic. Malachite columns and other veneered pieces also appear in St. Isaac's Cathedral and in collections across Europe, many of them gifts from Russian rulers.
Malachite in jewelry
Jewelers use malachite mostly as cabochons, beads, inlay and carved pieces. Good material has crisp, high-contrast banding, an even polish and no pits or cracks. Bull's-eye patterns centered in a cabochon are especially popular. Carvers use it for boxes, spheres, animal figures and tabletops, often veneered over a cheaper base.
Rings and bracelets are possible but risky. Quartz dust, which is in ordinary household dust, has a hardness of 7 and will scratch malachite over time. A bezel setting and occasional repolishing help. For daily-wear pieces, the Mohs hardness scale page explains why softer stones dull faster.
Some malachite is treated. Porous pieces may be impregnated with wax or resin to improve the polish and hold them together, and reconstituted malachite is made from crushed material bonded with resin. The gemstone treatments page covers impregnation and how labs detect it. Imitations include banded glass, plastic and dyed stones, and a gemologist can separate them by hardness, density and the fibrous structure seen under magnification.
Cutting safety
Malachite is a copper compound, and copper mineral dust is harmful to breathe or swallow. Lapidaries cut and polish it wet, which keeps the dust down, and wear dust masks and gloves. They also clean the water and slurry from their machines carefully. These precautions apply to cutting and sanding the raw material. A finished, polished stone does not shed dust in normal handling.
Care and cleaning
Malachite reacts with acids and breaks down under heat. Keep it away from household cleaners, ammonia, perfume and hot water. Do not use ultrasonic or steam cleaners. Clean it with a soft cloth and lukewarm water with a drop of mild soap, then dry it right away. The guide to cleaning jewelry safely lists other gems that need the same gentle method.
Store malachite apart from harder gems so it does not get scratched, and take it off before exercise, swimming or housework.
Frequently asked questions
Is malachite safe to wear?
Yes. The hazard comes from inhaling or swallowing dust during cutting and grinding. Polished malachite in jewelry does not release dust under normal wear.
How can you tell real malachite from an imitation?
Real malachite has fine fibrous bands with soft, slightly irregular edges and feels heavy for its size. Glass and plastic imitations often show bubbles, molded edges or bands that look painted on. A gemologist can confirm it with specific gravity and magnification.
Is malachite a birthstone?
No. Malachite is not on the standard modern or traditional birthstone lists. The birthstones by month page shows which gems are.
Why does malachite lose its shine?
It is soft, so dust and contact with harder objects scratch the surface. Acids in cosmetics and sweat can also etch it. A jeweler can repolish a dull piece.