Mineral Database (Saesneg yn unig)

Mineral Database (Saesneg yn unig)
Mineralogy of Wales

Woodwardite

Crystal System: Hexagonal
Formula: Cu4Al2SO4(OH)12.2-4H2O
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Copper aluminium sulphate hydroxide hydrate
Method(s) of Verification: Eaglebrook (Nant-y-cagl) Mine - Infra-red spectroscopy (Braithwaite, 1982) & XRD (W. Birch, National Museum of Victoria, Austalia, cited in Braithwaite, 1982).
Chemical Group:
  • Sulphates
Geological Context:
  • Supergene : post-mining oxidation & weathering deposits
Introduction: this is an inadequately characterized, post-mining, secondary copper mineral that forms porous crusts on mine walls, and coats rock fragments within mine dumps containing copper mineralization.
Occurrence in Wales: woodwardite was described as a new mineral species by Church (1866) on specimens from Cornwall. Similar material was identified from Carnarvonshire (Gwynedd), but later shown to be identical to the new mineral hydrowoodwardite (Mandarino, 2001). Hydrowoodwardite was approved as a new species in 1996 and is considered to be the copper-dominant analogue of glaucocerinite and carrboydite (Mandarino, 2001). Raade et al. (1985) showed the so-called woodwardite from two localities in North Wales to be the Cu-analogue of glaucocerinite, following the discovery by Nickel (1976) that, alleged woodwardite from Carnarvonshire was distinctly different to woodwardite from the type locality in Cornwall. Woodwardite has however, been confirmed from Eaglebrook (Nant-y-cagl) Mine in the Central Wales Orefield as pale blue micro-botryoidal coatings (Braithwaite, 1982).
Key Localities:
  • Eaglebrook (Nantycagl) Mine, Ceulanymaesmawr, Ceredigion: pale blue micro-botryoidal coatings, are described by Braithwaite (1982) from this locality and infra-red analysis shows a spectrum similar to that of woodwardite (Braithwaite, 1982).
References:
  • Braithwaite, R.S.W., 1982a Wroewolfeite in Britain.  Mineralogical Record, 13, 167-174.
  • Church, A.H., 1866   J. Chem. Soc. 19, 131.
  • Mandarino, J.A., 2001 New Minerals 1995-1999.  The Canadian Mineralogist Special Publication 4. 281 pp.
  • Nickel, E.H., 1976 New data on woodwardite.  Mineralogical Magazine, 40, 644-647.
  • Raade, G., Elliott, C.J., & Din, V.K., 1985 New data on glaucocerinite.  Mineralogical Magazine, 49, 583-590.