The material on which the following description is based was presented by Dr. A. L. Hall to the Department of Mineralogy at Cambridge, and I am greatly indebted to him and to Prof. A. Hutchinson for affording me the opportunity of describing it. The first account of the occurrence was given by Dr. Hall, recording from Aarkop, Magoloring, 'a beautiful delicately rose-coloured mica … in compact dark bluish-grey ore as thick, short, colmnnar aggregates not unlike little books of mica with pseudo-hexagonal outlines and showing the characteristic perfect basal cleavage … the mate: rial was found on the higher slopes defining the west side of Martha's Kloof'. This description was amplified somewhat in a later publication, with the addition of an analysis (see below). As noted therein the mineral also resembles that described by Chudoba as a manganophyllite allied to the phlogopite group, but the fuller description given below reveals important differences.