Sharp outstanding prismatic and acicular crystals of the rare sulphide krupkaite fom the type locality: Barbora Adit, Krupka, Usti Region, Bohemia, Czech Republic. — Photo: David Hospital · CC BY-SA 4.0
Krupkaite
Krupkaite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula PbCuBi₃S₆.
It crystallizes in the orthorhombic crystal system (space group Pmc2_1). It is a member of the Meneghinite structural group.
Key properties: specific gravity 6.98; Metallic. R1 –R2: (400) 39.8–46.9, (420) 40.0–46.7, (440) 40.1–46.3, (460) 40.2–46.2, (480) 40.1–46.3, (500) 39.9–46.5 luster.
IMA symbol Krp, IMA status: approved, named in 1974.
Rare in hydrothermal veins.
It is found associated with Gladite, bismuthinite, aikinite, bismuth, cassiterite, quartz.
The name is derived from the locality in the Czech Republic at Krupka.