Pellouxite

Pellouxite is a very rare silver sulphosalt only known from 3 localities worldwide, being this one from the type and most classic locality in Italy (Buca Della Vena Mine, Apuan Alps, Lucca Province, Tuscany). It occurs in this specimen as metallic acicular and prismatic crystals with good contrast with the white matrix — Photo: David Hospital · CC BY-SA 4.0

Pellouxite

Pellouxite is an IMA-recognized mineral species in the halide class, with the chemical formula (Cu,Ag)₂Pb₂₁Sb₂₃S₅₅ClO.

It crystallizes in the monoclinic crystal system (space group C2/m).

Key properties: specific gravity 5.97; Brown streak; Metallic. Bireflectance: Weak, white to white-gray. Anisotropism: Distinct luster.

IMA symbol Plx, IMA status: approved, named in 2001.

Formed by high chlorinity hydrothermal fluids in cavities and vugs in calcite veins that cut a Ba-Fe deposit, as well as, the enclosing greenschist facies phyllite and dolomitic limestone.

It is found associated with Zinkenite, boulangerite, robinsonite, tintinaite, and, rarely, scainiite and pillaite; and tetrahedrite, bournonite, sphalerite, cinnabar, galena, andorite.

The mineral was named to honor Professor Alberto Pelloux (1868-1947), curator of the mineralogical Museum, University of Genoa, Italy, and past President of the “Società Geologica Italiana”.