COBALTAUSTINITE on CALCITE

SPECIMEN DESCRIPTION

Cobaltaustinite is a rare secondary calcium cobalt arsenate hydroxide mineral that forms a series with the zinc analogue - Austinite. This specimen was previously labelled as Cobaltoan Austinite - a cobalt-rich variety of Austinite - but most material of this appearance from the Bou Azzer Mining District falls into the domain of Cobaltaustinite. It is a very rich, and large, display quality specimen, with crystal-lined cavities within Calcite coated with finely botryoidal crusts - some quite thick - of matt, leaf-green, to darker green Cobaltaustinite. At one end of the main cavity sparkling uncoated small prismatic Calcite crystal dominate with a fairly rapid transition across the cavity to Calcite crystals entirely covered with Cobaltaustinite. Ex Nick Hawes collection.