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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.

Semseyite
Semseyite2.jpg
Semseyite - Brioude-Massiac (Massif Central) France (11x3.5cm)[1]
General
CategorySulfosalt mineral
Formula
(repeating unit)
Pb9 Sb 8 S21
Strunz classification2.HC.10d
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/c
Unit cella = 13.64 Å, b = 11.96 Å
c = 24.46 Å; β = 105.87°; Z = 4
Identification
ColorDark gray to black
Crystal habitTabular, elongated prismatic crystals, commonly twisted; rosettelike groups
CleavagePerfect on {112}
TenacityBrittle
Mohs scale hardness2.5
LusterMetallic
Diaphaneityopaque
Specific gravity6.15
References[2][3][4]

Etymology and historyEdit

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).

OccurrenceEdit

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]

ImagesEdit

ReferencesEdit

  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” Archived 2011-02-13 at the Wayback Machine