Location: Panasqueira Mine, Covilhã, Castelo Branco, Portugal.
Curved rhombohedral crystals of Siderite associated with Cassiterite (tetragonal prismatic crystal at the top with 7x7x4mm). Sample with 4.0 x 3.5 x 2.0cm. 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.