¹This paper collects together the mineralogical details contained in the author's report on ‘The geology of the Postmasburg manganese deposits and the surrounding country’, Geological Survey of the Union of South Africa (Special Publication), Pretoria, 1929, 104 pp. [Min. Abstr., vol. 4, p. 232], with the addition of two new chemical analyses by Mr. H. G. Weall and some other new matter.
With a note on the Crystallography by L. J. SPENCER, F.R.S.