Crystal System: Hexagonal
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Aluminium sulphate hydroxide hydrate
Chemical Formula: Al4(SO4)(OH)10.5H2O
Method(s) of Verification: Moel Goedog - XRD & DTA analysis; Parys Mountain - XRD.

Chemical Group:

  • Sulphates

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Introduction: a secondary mineral formed by the dehydration of hydrobasaluminite under weathering conditions.
Occurrence in Wales: Ball (1969) provided the first account of basaluminite from Wales from shattered black shales of the Clogau Group, exposed on a hillside near Harlech. More recently, investigations into the post-mining mineralogy of Parys Mountain have produced a second account of basaluminite in Wales.

Key Localities:

  • Moel Goedog, near Harlech, Gwynedd: Ball (1969) described a single cavity (c. 2 x 1 cm diameter) in black shale, filled with a white earthy mineral which was subsequently shown to be basaluminite, from a small roadside pit on the slopes of Moel Goedog.
  • Parys Mountain, Anglesey: basaluminite, from this locality, was listed without description by Jenkins et al. (2000).

There are no key localities for this specimen.


  1. Ball, D.F., 1969. Basaluminite from Cambrian rocks near Harlech. Mineralogical Magazine, 37, 291-293.
  2. 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.

There are no references for this specimen.