A great crystal specimen of the rare Copper Antimony Sulphide Chalcostibite. The elongate crystals of Chalcostibite are intergrown, exhibiting the classic overgrowth of bright blue Azurite and minor green Malachite. The main Chalcostibite crystal displays well in the vertical position, with a flat top termination. The matrix is a light biscuit coloured rock with colourless to translucent white Calcite. A fine example of Chalcostibite from Morocco, rare in this size of crystal - such specimens first came to notice in 1919.