Crystal System: Monoclinic
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Chemical Composition: Manganese silicate fluoride hydroxide
Chemical Formula: Mn9(SiO4)4(OH,F)2
Method(s) of Verification: Llŷn Dywarchen - EMPA (Bennett analysis no. 12459 in Bennett, 1987a)
- 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.
- 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).
- Bennett, M.A., 1987a. The Cambrian manganese deposits of North Wales. Unpublished Ph.D. thesis, University of Leeds.