Vrbaite Locality: Allchar (Alsar), Roszdan, Republic of Macedonia ( Locality at mindat.org ) Picture width 0.8 mm. Collection and photograph Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0
Vrbaite
A dark-red thallium-mercury-antimony-arsenic sulfosalt — pyramidal crystals named for Karel Vrba.
Intro adapted from Wikipedia (CC BY-SA).
Vrbaite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Hg₃Tl₄As₈Sb₂S₂₀.
It crystallizes in the orthorhombic crystal system (space group Aba2).
Key properties: Mohs hardness 3.5; specific gravity 5.3; Pale red with a yellow tone streak; Submetallic to metallic luster; optically biaxial.
IMA symbol Vrb, grandfathered status — known before the IMA’s founding, named in 1912.
Found in a hydrothermal deposit with other As–Tl sulfide minerals.
It is found associated with Realgar, orpiment.
The name refers to Professor Karel Vrba (1845–1922), University of Prague, Prague, Czechoslovakia, Czech mineralogist.