Hardness: 3.5 - 4 on the mohr's scale.
Brochantite is a sulfate mineral, one of a number of cupric sulfates. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it is named for its discoverer, the French geologist and mineralogist, A. J. M. Brochant de Villiers (1772–1840). Crystals of brochantite can range from emerald green to black-green to blue-green, and can be acicular or prismatic. Brochantite is often associated with minerals such as malachite, azurite, and chrysocolla, and may form pseudomorphs with these minerals.