Brochantite,  Australia.

Brochantite, Australia.

Brochantite is a sulphate mineral, Cu4SO4(OH)6, often referred to as a secondary mineral of copper. The encrustation on this specimen is a mix of brochantite and another copper secondary mineral, probably malachite in the form of minute botryoidal clusters ( see insets).  The brochantite crystals are prismatic, and very small, scattered here and there throughout the specimen, and are a very slightly darker green.  This Australian specimen was collected in the 1960's by our club co-founder, Jim Nicholls, while he was working there on rocket technology.