Wolframite (Ferberite).
  
From: Panasqueira Mine, Covilhã, Castelo Branco, Portugal.
  
Tabular prism with vertical striation, with 4.0 x 2.0 x 1.0cm and 40 grams, black, opaque and with semi-metallic lustre. 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.