Bournonite (crystals, associated with jamesonite and quartz, tetragonal system) is made up of PbCuSbS3, containing 42.5% plumbum, 13.0% copper, and 24.7% antimony and as well as traces of impunities like arsenic, iron, silver, zinc, manganese, etc. It is brittle. Under the metallographic microscope, the reflected color is white and it takes slight bluish grey in oil.