AZURITE with MALACHITE (miniature)

Azurite has the chemical formula Cu3(CO3)2(OH)2, with copper(II) cations bonded to both carbonate and hydroxide anions. It is one of two relatively common basic copper(II) carbonate minerals, the other being the bright green malachite. Aurichalcite, on the other hand, is a rare basic carbonate mineral containing copper and zinc. Simple copper carbonate (CuCO3) is not found in nature due to the strong affinity of the Cu2+ ion for the hydroxide anion HO−.

Malachite is a mineral composed of copper carbonate hydroxide, represented by the chemical formula Cu2CO3(OH)2. This opaque mineral features distinctive green bands and crystallizes within the monoclinic system. It typically forms in botryoidal, fibrous, or stalagmitic shapes in fractures and subterranean environments, where the presence of hydrothermal fluids and the water table facilitate chemical precipitation. While individual crystals are uncommon, they can appear as slender or acicular prisms, and pseudomorphs resembling more tabular or blocky azurite crystals are also found.