Gudmundite Locality: Pezinok, Pezinok Co., Bratislava Region, Slovakia Dimensions: 5.0 cm x 4.9 cm x 2.1 cm This species gets its name from the Type Locality of Gudmundstorp, Sweden. Gudmundite is a relatively rare iron antimony sulfide, and good quality specimens are certainly few and far between. This relatively rich miniature piece features small bright, metallic, platy crystals on matrix from this vein-type antimony deposit in Slovakia. The crystals are <1mm, but some of them are beautiful under high magnification. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Gudmundite
Gudmundite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula FeSbS.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Arsenopyrite structural group.
Key properties: Mohs hardness 5–6; specific gravity 6.72; Metallic luster.
IMA symbol Gu, grandfathered status — known before the IMA’s founding, named in 1928.
A late-stage hydrothermal mineral formed in sulfide deposits.
It is found associated with Pyrite, pyrrhotite, chalcopyrite, lead sulfantimonides, antimony, bismuth, kermesite, arsenopyrite, argentian gold.
The name refers to the occurrence at Gudmundstorp, Sweden.