Location: Mina da Panasqueira, Covilhã, Castelo Branco, Portugal.
Irregular black Sphalerite cluster (Marmatite) with several cleavage planes, vitreous to sub-metallic lustre, sprinkled with small inclusions of golden yellow Chalcopyrite, green Sericite (variety of Muscovite) and a small crystal of Fluorapatite. 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 schistas and graywackes.