Metallic crystals of the very rare thallium mineral weissbergite, with only 4 localities known worldwide. From: Lookout Pass, Little Valley, Tooele County, Utah, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Weissbergite
Weissbergite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula TlSbS₂.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Weissbergite structural group.
Key properties: Mohs hardness 1.5; specific gravity 5.79; Dark gray streak; Bright metallic luster.
IMA symbol Wsb, IMA status: approved, named in 1975.
Found in late-stage hydrothermal veins that brecciate silicified dolomitic carbonate rocks.
It is found associated with Stibnite, quartz.
The name refers to Dr. Byron G. Weissberg, Chemistry Division, D.S.I.R., New Zealand.