Mineral Database (Saesneg yn unig)

Mineral Database (Saesneg yn unig)
Mineralogy of Wales

Hexahydrite

Crystal System: Monoclinic
Formula: MgSO4.6H2O
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Magnesium sulphate hydrate
Method(s) of Verification: Treharris - XRD (National Museum of Wales, NMW X-282).
Chemical Group:
  • Sulphates
Geological Context:
  • Supergene : in situ natural oxidation & weathering deposits
Introduction: hexahydrite is a member of the hexahydrite group, that forms typically through the dehydration of epsomite.
Occurrence in Wales: a number of specimens from Treharris in the National Museum of Wales Mineral Collection display hexahydrite alteration from epsomite. This is the only record of hexahydrite from Wales.
Key Localities:
  • Treharris, South Wales: hexahydrite is present on a number of specimens labelled ‘epsomite’ in the mineral collection of the National Museum of Wales. It is likely that this formed through the dehydration of epsomite in a museum environment (Bevins, 1994).
References:
  • Bevins, R.E., 1994 A Mineralogy of Wales  National Museum of Wales, Geological Series No. 16, Cardiff, 146pp.