Mineral Database (Saesneg yn unig)
Gudmundite
Crystal System: Monoclinic
Formula: FeSbS
Status of Occurrence: Discredited Occurrence
Distribution: None - Discredited
Chemical Composition: Iron antimony sulphide
Method(s) of Verification: Esgairhir Mine - original identifcation visual, subsequently discredited by XRD/EMPA (Mason, 1998).
Chemical Group:
- Sulphides
Geological Context:
- Hydrothermal : epithermal polymetallic veins & pipes
Introduction: gudmundite can occur in a wide variety of hydrothermal ore deposits in association with other sulpharsenides and sulphantimonides, but is usually only an accessory or minor member of any given assemblage.
Occurrence in Wales: in 1988, Rust & Mason reported, in describing the primary mineral paragenesis at Esgairhir Mine in Central Wales, the presence of laths and prismatic crystals of a mineral with the optical properties of gudmundite, overgrowing 'linnaeite' and millerite. Subsequent analytical work, however, correctly identified this mineral to be tucekite (Mason, 1998): therefore gudmundite and references to it at Esgairhir Mine should be amended appropriately.
Key Localities:
There are no key localities for this specimen.
References:
- Tucekite, a mineral new to Britain, and other rare ore minerals from the Central Wales Orefield. UK Journal of Mines and Minerals, 19, 30-36.
- The minerals of Esgair-Hir mine, Dyfed, Wales. UK Journal of Mines & Minerals, 5, 35-43.