The green copper carbonate commonly used as a decorative stone and pigment is malachite.
Malachite is a copper carbonate hydroxide with the formula Cu₂CO₃(OH)₂. It usually forms near the surface of copper ore deposits, where circulating water alters primary copper minerals. Its vivid green colour ranges from pale bands to deep concentric patterns, making polished malachite especially recognizable.
Ancient civilizations used malachite as a mineral pigment and ornamental material. Ground malachite produced green paint, while larger pieces were carved into objects, beads, inlays, and decorative panels. Today, specimens and polished material remain popular with collectors and lapidaries, although copper minerals should not be treated as food or casually converted into powders.
Malachite is often confused with azurite, another copper carbonate mineral. Azurite is typically blue, while malachite is green; the two can occur together in the same oxidized copper deposits. Malachite is also softer than quartz, so polished surfaces can scratch more easily than many people expect.