Acid and Basic Sulphates – Brochantite Composition

Brochantite
A basic sulphate of copper, CuSO4.3Cu(OH)2. orthorhombic. Slender prismatic crystals , vertically striated, often acicular. Some times massive reniform. Perfect pinacoidal cleavage. H. = 3.5-4. G. = 3.9. Vitreous luster. Emerald to blackish green in color. Transparent to translucent. Fusible (3.5). Copper globule when fused with sodium carbonate on charcoal. Hidrochloric acid solution with barium chloride gives white precipitate of barium sulphate. Water in C.T. A rare mineral found in the oxidized portions of copper veins.