Mineral description : Boulangerite

Boulangerite from Nasafjäll silver mine, Lappland.

Mineral class Sulphides : Tetrahedrite bournonite boulangerite group
Chemical formula Pb5Sb4S11
Crystal system Monoclinic
Habitus Crystals rare, mostly as radiating and fibric masses.
Cleavage Good, fracture uneven.
Hardness 2.5-3
Density 5.8-6.2
Color Led gray to bluish gray.
Streak Brownish black.
Luster Dull or metallic
Description  
Occurance In hydrothermal veins.
Associates Galena, pyrite, sphalerite, tetrahedrite, tennantite, proustite, quartz.
Notes Fuses very easily.
Does not react with cold weak acids, but dissolves in hot strong acids.
Locations A rare mineral in Sweden.
  • Nasafjäll silver mine, Lappland. Common as fibric masses with galena and sphalerite. Rusty tarnish.
  • Sala silver mine, Västmanland. Used to be a good locality. As fibric masses in a grainy mixture of galena and sphalerite. Also in dolomite.
  • Also found in Boliden, Rakkejaur and Stekenjokk.

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axelsson@acc.umu.se
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Last changed : 1998-03-07