Crystal System: Monoclinic
Status of Occurrence: Unconfirmed Occurrence
Distribution: Rare
Chemical Composition: Calcium sodium potassium aluminium silicate hydrate
Chemical Formula: (Ca,Na,K)5(Si,Al)36O72.24H2O
Method(s) of Verification: not known.

Chemical Group:

  • Silicates

Geological Context:

  • Hydrothermal
  • Metamorphic: low-grade
Introduction: heulandite is a zeolite mineral, and forms a group consisting of heulandite-Ca, heulandite-K, heulandite-Na, and heulandite-Sr.
Occurrence in Wales: although the presence of a heulandite mineral from Wales has not been verified a reference in Mineralogical Magazine (volume 17, p.27), refers to specimens of ‘heulandite and prehnite from Wales’ being exhibited by Mr. Arthur Russell at a General Meeting of the Mineralogical Society held on March 17, 1914.

Key Localities:

There are no key localities for this specimen.


There are no references for this specimen.