Location: Panasqueira Mine, Covilhã, Castelo Branco, Portugal.
Irregular black Sphalerite aggregate (Marmatite) with several cleavage planes, vitreous to sub-metallic lustre, sprinkled with small inclusions of golden yellow Chalcopyrite and covered with small rhombohedrons of white Dolomite and cubes of Pyrite. Sample with 4.2 x 2.5 x 2.1cm and 29 grams. Formed in mineralized veins of quartz, sulfides, wolframite, cassiterite, micas, fluorite, carbonates, among others, associated with the generation of a greisen dome by granitic intrusion in Paleozoic schists and graywackes.