Location: Panasqueira Mine, Covilhã, Castelo Branco, Portugal.
Aggregate of black isometric crystals of Sphalerite (Marmatite) with several striated faces, sub-metallic lustre, with golden yellow Pyrite in the form of a small aggregate of twinned pyritohedron crystals, covered with some small crystals of yellowish Siderite. Sample with 3.1 x 2.6 x 2.1cm and 35 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.