Location: Panasqueira Mine, Covilhã, Castelo Branco, Portugal.
Irregular black Sphalerite aggregate (Marmatite) with several cleavage planes, vitreous to sub-metallic lustre, sprinkled with small crystals of golden yellow Chalcopyrite and green Sericite green (variety of Muscovite). Sample with 3.0 x 2.8 x 2.0cm and 20 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 shists and graywackes.