bournonite, sulfosalt mineral, a lead, copper, and antimony sulfide (PbCuSbS3), that occurs as heavy, dark crystal aggregates and masses with a metallic lustre in association with other sulfur-containing minerals in many locations, including the Harz Mountains of Germany; a number of localities in Italy; Bolivia; Peru; Ontario, Canada; and the western United States. Its crystals have orthorhombic symmetry. For detailed physical properties, see sulfosalt (table).