Boulangerite or antimonbleiblende is an uncommon monoclinic orthorhombic sulfosalt mineral, lead antimony sulfide, formula Pb5Sb4S11. It was named in 1837 in honor of French mining engineer Charles Boulanger (1810–1849), and had been a valid species since pre-IMA. It was first described prior to 1959, and is now grandfathered.
Boulangerite, covering a block of limestone
Sulfosalt minerals are sulfide minerals with the general formula AmBnXp, whereA represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium
B usually represents semi-metal such as arsenic, antimony, bismuth, and rarely germanium, or metals like tin and rarely vanadium
X is sulfur or rarely selenium and/or tellurium.
Structure of proustite Ag3AsS3, a classic sulfosalt, which can be viewed as the Ag+ salt of AsS3−3. Sulfosalts characteristically feature A–S–B linkages, where A and B are different metals or metalloids.
As illustrated by this specimen of proustite, sulfosalt minerals are often deeply colored.