Mineral Database

Mineral Database
Mineralogy of Wales

Clinotyrolite

Crystal System: Monoclinic
Formula: Cu2+9Ca2[(As,S)O4]4(O,OH)10.10H2O
Status of Occurrence: Unconfirmed Occurrence
Distribution: Rare
Chemical Composition: Copper calcium arsenate sulphate hydroxide hydrate
Method(s) of Verification: none.
Chemical Group:
  • Arsenates
  • Sulphates
Geological Context:
  • Supergene : in situ natural oxidation & weathering deposits
Introduction: clinotyrolite is a secondary mineral found typically in the oxidized zone of copper-bearing ore bodies.
Occurrence in Wales: the presence of this species is as yet unconfirmed. However, a number of tyrolite occurrences have produced XRD patterns that do not match ideal tyrolite (see for example Cotterell et al., 2011), while tyrolite from Gwaith-yr-Afon Mine was described by Rust & Mason (1994) as sulphatian. Further research is required to establish the true identity of all Welsh tyrolites.
Key Localities:
There are no key localities for this specimen.
References:
  • Cotterell, T.F., Green, D.I., Hubbard, N., Mason, J.S., Starkey, R.E. and Tindle, A.G., 2011 The Mineralogy of Dolyhir Quarry, Old Radnor, Powys, Wales.  UK Journal of Mines and Minerals, 32, 5-61.
  • Rust, S.A. & Mason, J.S., 1994 An unusual occurrence of arsenate minerals at Gwaith-yr-Afon mine, Dyfed, Wales.  Journal of the Russell Society, 5(2), 109-113.