- Benallt Mine, Llŷn, Gwynedd: clove-brown, alleghanyite was identified from this locality by Dr Brian Mason and reported by Campbell Smith et al. (1944). Both individual crystals and composite crystals occur with tephroite (Mn2+2SiO4) as criss-crossing veins cutting banalsite, calcite and baryte in dark spotted manganese ore from the footwall side of the No. 1 ore-body (More specifically – ‘by the No. 1 chute 50-60 feet west of the main shaft and some 10-20 feet above the 130 foot level’, Campbell Smith et al. (1944)). The composite alleghanyite crystals are up to 20 mm long and vary in thickness from microscopic to 2 mm and have a blade-like form. Compared to alleghanyite from the type locality (Bald Knob, Alleghany County, North Carolina, USA), the Benallt occurrence is Ti-rich, containing up to 4.8 wt% TiO2 (Campbell Smith et al., 1944).
There are no key localities for this specimen.
- Brown, M.J. & Evans, A.D., 1989. Geophysical and geochemical investigations of the manganese deposits of Rhiw, western Llyn, North Wales. British Geological Survey Technical Report WF/89/14 (BGS Mineral Reconnaissance Programme Report No.102).
- Campbell Smith, W., Bannister, F.A., & Hey, M.H., 1944b. Banalsite, a new barium-felspar from Wales. Mineralogical Magazine, 27, 33-46.
There are no references for this specimen.