Brochantite - Cu₄SO₄(OH)₆

Habit: Green, emerald green, greenish black or light green. Crystals stout prismatic to acicular, also tabular; loosely coherent aggregates of acicular crystals, groups and drusy crusts, massive or granular. Vitreous luster, somewhat pearly on cleavages; transparent to translucent. Pale green streak.

Environment: Common in the oxidized zone of copper deposits. Forms in conditions of low acidity, principally in arid regions.

Etymology: Named for A.J.M. Brochant de Villiers (1772-1840), a French geologist and mineralogist.