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Semseyite - Brioude-Massiac (Massif Central) France (11x3.5cm)[1]
Category Sulfosalt mineral
(repeating unit)
Pb9 Sb 8 S21
Strunz classification 2.HC.10d
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group C2/c
Unit cell a = 13.64 Å, b = 11.96 Å
c = 24.46 Å; β = 105.87°; Z = 4
Color Dark gray to black
Crystal habit Tabular, elongated prismatic crystals, commonly twisted; rosettelike groups
Cleavage Perfect on {112}
Tenacity Brittle
Mohs scale hardness 2.5
Luster Metallic
Diaphaneity opaque
Specific gravity 6.15
References [2][3][4]

Semseyite is a rarely occurring sulfosalt mineral and is part of the class of lead antimony sulfides. It crystallizes in the monoclinic system with the chemical composition Pb9Sb8S21. The mineral forms dark gray to black aggregates.

Etymology and history[edit]

Semseyite was first described for an occurrence in the Felsöbánya mine in Baia Sprie, Romania in 1881 by József Sándor Krenner (1839–1920). The mineral was named after Hungarian mineralogist Andor von Semsey (1833–1923).

Location: Baia Sprie, Maramures County, Romania


Semseyite forms in hydrothermal solutions at temperatures between 300 and 350 °C.[5] It occurs in association with bournonite, jamesonite, sphalerite, zinkenite, sorbyite, guettardite, jordanite, diaphorite, galena, pyrite, chalcopyrite, tetrahedrite, arsenopyrite and siderite.[2]


  1. ^ J.J. Périchaud : "Metal Layers of the District with Antimony of Brioude-Massiac (French Massif Central)", BRGM, 1968
  2. ^ a b Handbook of Mineralogy
  3. ^ Mindat
  4. ^ Webmineral data
  5. ^ Andreas Kamrath: “Geology and mineralogy of ore stores Herja”