Chemistry:Vrbaite

Vrbaite
Vrbaïte, Crven Dol Mine, Allchar (Alsar), Roszdan, North Macedonia
General
Category	Mineral
Formula (repeating unit)	Tl4Hg3Sb2As8S2
Strunz classification	Template:Strunz-inline
Dana classification	03
Crystal system	orthorhombic
Crystal class	Dipyramidal ; $C$ $mca$ {C 2/m 2/c 2Template:Ind/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

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".

Type locality: Allchar deposit, Ržanovo mine (mk), Kavadarci Municipality, North Macedonia.