Vrbaite

Vrbaite (symbol: Vrb) is an opaque to subtranslucent brittle mineral with chemical formula Tl₄Hg₃Sb₂As₈S₂₀ and pyramidal crystals. It is names after Czech mineralogist Karel Vrba [cs]. It is bluish white with red internal reflections and dark red in translucent thin fragments. It is classified in the class "sulfides and sulfosalts".^[1][2]

CategoryMinerals

FormulaTl4Hg3Sb2As8S2

Strunz classification2 SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)

 2.H Sulfosalts of SnS Archetype
  2.HF With SnS and PbS archetype structure units

   2.HF.20 Vrbaite Tl4Hg3Sb2As8S20
Space Group C mca
Point Group 2/m 2/m 2/m

Dana classification03.07.15.01

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Vrbaite
Vrbaïte, Crven Dol Mine, Allchar (Alsar), Roszdan, North Macedonia
General
Category	Minerals
Formula	Tl4Hg3Sb2As8S2
Strunz classification	2 SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)  2.H Sulfosalts of SnS Archetype   2.HF With SnS and PbS archetype structure units    2.HF.20 Vrbaite Tl4Hg3Sb2As8S20 Space Group C mca Point Group 2/m 2/m 2/m
Dana classification	03.07.15.01
Crystal system	orthorhombic
Crystal class	Dipyramidal ; ${\displaystyle C}$ ${\displaystyle mca}$ {C 2/m 2/c 2 India/a}
Identification
Color	black, gray-black, bluish, dark red; on polished sections, bluish white with internal red highlights
Fracture	uneven/irregular to conchoidal
Tenacity	3,5
Density	5,27-5,33
Refractive index	n = 2,72-2,73
Dispersion	r > v
Ultraviolet fluorescence	aucune
Absorption spectra	opaque

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Type locality: Allchar deposit, Ržanovo mine [mk], Kavadarci Municipality, North Macedonia.^[2][3]