Classic Cornish specimen of Blister Copper from the Carn Brea Mine, Illogan. Characteristic botryoidal Chalcopyrite has a dark metallic patine, over the metallic yellow interior. Formed on a white vein Quartz with typical dull green Chlorite. The underside of the specimen shows colourless glassy hexagonal micro-crystals of Apatite (Francolite). A fine small cabinet specimen of the Chalcopyrite variety.