Barium-felspars (celsian and paracelsian) from Wales

In 1911 an interesting find of barium-felspars was made in the Benallt manganese mine near Rhiw in the Lleyn peninsula of Carnarvonshire. A brief preliminary note on the occurrence was given by Mr. Arthur Russell in the same year. At the same time he very generously handed over to me for crystallographic and optical description a selection of the material he had collected, while he himself made a start on the chemical analysis of the material. Chemical analyses have now, at last, been made by Miss Hilda Bennett in the Mineral Department of the British Museum, and it therefore seems time to collect together the large volume of notes on the work done in 1911.