The Collaborative International Dictionary
Boulangerite
Boulangerite \Bou*lan"ger*ite\, n. [From Boulanger, a French mineralogist.] (Min.) A mineral of a bluish gray color and metallic luster, usually in plumose masses, also compact. It is a sulphide of antimony and lead.
Wiktionary
boulangerite
n. (context mineral English) A lead antimony sulfide mineral that forms metallic grey monoclinic crystals.
Wikipedia
Boulangerite
Boulangerite is a sulfosalt mineral, lead antimony sulfide, formula PbSbS. 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.