Black crystals of the extremely rare thallium mineral jankovicite in a matrix of realgar from a new find in Shimen, China (Jiepaiyu, Shimen County, Hunan Province, China), a locality that was only previously known for orpiment and realgar crystals. — Photo: David Hospital · CC BY-SA 4.0
Jankovićite
Jankovićite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Tl₅Sb₉(As,Sb)₄S₂₂.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2; specific gravity 5.12; Brown-violet streak; Metallic luster.
IMA symbol Jkv, IMA status: approved, named in 1993.
Found in a hydrothermal Tl–Sb–As deposit, formed at low temperatures.
It is found associated with Realgar, stibnite, pyrite.
The mineral was named to honor Prefessor S. Janković (1925–), who has worked in the Allchar region.