Boulangerite is a sulfosalt mineral, lead antimony sulfide, formula Pb₅Sb₄S₁₁. It was named in 1837 in honor of French mining engineer Charles Boulanger (1810-1849). It forms metallic grey monoclinic crystals. Sometimes the crystals form a fine feathery mass which has been called plumosite. Boulangerite is used as a lead ore.