Dufrenoysite - Encyclopedia
Class : Sulfides and sulfosalts
Subclass : Sulfosalts
Crystal system : Monoclinic
Chemistry : Pb2As2S5
Rarity : Very rare
Dufrenoysite is a very rare lead sulfoarsenide, present in hydrothermal gold deposits (Hemlo, Canada), and in hydrothermalized dolomites (Binn, Switzerland). It was named in honor of Pierre Armand Dufrénoy, professor of Mineralogy at the Ecole des Mines de Paris. It forms tabular crystals with a maximum size of 2.5 cm, moderately elongated along [100] or [010], striated along [100], lead gray to steel gray in color. It accompanies various arsenic and antimony minerals (realgar, orpiment, tetrahedrite) and, in Binn, other extremely rare lead sulfoarsenides (rathite, baumhauerite, sartorite, etc...).
Main photo : Dufrenoysite and realgar from Lengenbach Quarry, Fäld, Binn, Goms, Valais, Switzerland © Joy Desor
Dufrenoysite in the World
Twinning
A twin is known on {001}.
Fakes and treatments
No fake listed for this mineral species.
Hardness : 3
Density : 5.50 to 5.57
Fracture : Conchoidal
Streak : Brown
TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None
Solubility : -
Magnetism : None
Radioactivity : None