Mineral Database

Mineral Database
Mineralogy of Wales

Eggletonite

Crystal System: Monoclinic
Formula: (Na,K,Ca)1-2(Mn)6(Si,Al)10O24(OH)4.7-11H2O
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Distribution: Rare
Chemical Composition: Hydrated sodium-manganese aluminosilicate hydroxide
Method(s) of Verification:

Benallt Mine: electron microprobe analysis on NHM specimen no. BM 1949,164 published in Dunn et al. (1983) and SEM EDS at the National Museum of Wales (specimen no. NMW 2006.4G.M.2b).

Chemical Group:
  • Silicates
Geological Context:
  • Metamorphic : low-grade
Key Localities:
  • Benallt Mine, Llŷn, Gwyneddŷ:
References:
  • Dunn, P.J., Peacor, D.R., Nelen, J.E. & Ramkin, R.A., 1983 Ganophyllite from Franklin, New Jersey; Pajsberg, Sweden; and Wales; new chemical data.  Mineralogical Magazine, 47, 563-566.
  • Tindle, A.G., 2008 Minerals of Britain and Ireland. 

    Terra Publishing.