Boulangerite
Image: Darla Sondrol (CC0)
Mineral NameBoulangerite
Chemical FormulaPb5Sb4S11
Mohs Hardness2.5
Crystal Systemmonoclinic
Lustermetallic
Streak Colorreddish-brown to black
Cleavagegood on {010}
Fractureuneven
Specific Gravity6.2
Colorslead-gray, bluish-gray, steel-gray, blackish-gray
Transparencyopaque
Type LocalityMolières, Gard, France
Mineral Groupsulfides
Usesore of lead, ore of antimony, collector
Associated Mineralsgalena, sphalerite, pyrite, arsenopyrite, tetrahedrite, bournonite, stibnite, quartz, siderite
Rarityuncommon
Description
Boulangerite typically forms as fibrous, acicular, or plumose aggregates, often with a metallic lead-gray to steel-gray color, as seen in the image.
Geological Context
This sulfosalt mineral forms in low-temperature hydrothermal veins, commonly found in lead-zinc deposits where it is associated with other sulfide minerals.
