Mineral Database

Mineral Database
Mineralogy of Wales

Sonolite

Crystal System: Monoclinic
Formula: Mn9(SiO4)4(OH,F)2
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Distribution: Rare
Chemical Composition: Manganese silicate fluoride hydroxide
Method(s) of Verification: Llŷn Dywarchen - EMPA (Bennett analysis no. 12459 in Bennett, 1987a)
Chemical Group:
  • Silicates
Geological Context:
  • Metamorphic : low-grade
Introduction:

sonolite belongs to the humite group of minerals.

Occurrence in Wales:

the manganese ore bearing strata in the Harlech Dome area are of Cambrian age and bear a range of manganese minerals. Sonolite forms part of this assemblage, but has only been identified by electron microprobe analysis.

Key Localities:
  • Llŷn Dywarchen, Moel Ysgyfarnogod, Gwynedd: Bennett (1987a) reported the presence of rare orange-yellow Mn-humite associated with barite in a micro-concretion and also in adjacent carbonate-rich red laminated ore in the manganese ore bed of the Hafotty Formation (e.g. National Museum of Wales specimen NMW 24.479.GR32).
References:
  • Bennett, M.A., 1987a The Cambrian manganese deposits of North Wales.  Unpublished Ph.D. thesis, University of Leeds.