BROCHANTITE (from the name of the French mineralogist André-Jean-François-Marie Brochant de Villiers * EN: brochantite; DE: Brochantit; FR: brochantite; ES: brochantita; RU: брошантит) is the mineral of the class of sulfates, Cu4[SO4](OH)6. It contains 69-70% of CuO. It crystallizes itself into the monoclinic crystal system. The crystal structure is sub-layered, and is formed of the CuO(OH)5 octahedra. The crystal habit is thick-prismatic, to acicular, less often tabular; there are usual the twin crystals. It often forms the druse-alike intergrowths, small crusts, granular aggregates; there have been observed the pseudomorphoses on malachite and azurite. The colour is emerald green to dark green; it is transparent, to translucent. The cleavage is perfect. The hardness is 3.5-4. The density is 3970 kilograms per cubic metre.

Brochantite is the characteristic supergene mineral within the zone of oxidation within the copper deposits within the arid regions, where it may be found together with malachite, azurite, cuprite, chrysocolla, and other minerals (for example, the Gumeshevskiy deposit, at the Urals mountains; the Broken Hill deposit, within Australia).