Crystal System: Hexagonal
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Iron sulphate hydrate
Chemical Formula: Fe2(SO4)3.9H2O
Method(s) of Verification: Parys Mountain - XRD (Dr. D. Jenkins, University College of North Wales, Bangor).

Chemical Group:

  • Sulphates

Geological Context:

  • Supergene: post-mining oxidation & weathering deposits
Introduction: a secondary iron sulphate that typically forms in post-mining environments, in association with other sulphate species.
Occurrence in Wales: coquimbite is one of a number of rare, post-mining, sulphate minerals that have been discovered as a result of detailed investigations into the surface and underground workings at Mynydd Parys (Parys Mountain) on Anglesey (Jenkins et al., 2000).

Key Localities:

  • Parys Mountain, Anglesey: coquimbite occurs, with copiapite and other ferric sulphates, as encrustations which occur in overhangs and recesses and other sites protected from the elements in the two major opencasts (Jenkins et al., 2000).


  1. Jenkins, D. A., Johnson, D. B. & Freeman, C., 2000. Mynydd Parys Cu-Pb-Zn mines: mineralogy, microbiology and acid mine drainage. pp. 161-179. In: Environmental Mineralogy: Microbial Interactions, Anthropogenic Influences, Contaminated Land and Waste Management (Cotter-Howells, J. D., Campbell, L. S., Valasami-Jones, E. & Batchelder, M., eds.). The Mineralogical Society of Great Britain & Ireland, London.