MALACHITE and CHRYSOCOLLA

This specimen comes from an old collection and is rare. The mine is closed.

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.

Chrysocolla is a hydrous copper phyllosilicate mineral and mineraloid characterized by the formula Cu2 – xAlx(H2Si2O5)(OH)4⋅nH2O (where x < 1) or (Cu, Al)2H2Si2O5(OH)4⋅nH2O. The mineral's structural composition has been debated, with a 2006 spectrographic study indicating that what is commonly recognized as chrysocolla might actually be a combination of the copper hydroxide spertiniite and chalcedony.