Corundum is one of those rather exceptional rock-formers whose mode of origin is not fully explained, and it is, accordingly, of interest to put on record any new localities for the mineral, together with the features they present. Fragments of it have frequently been found among the old gravels of the Limpopo River, along the Transvaal-Rhodesian and Transvaal-Bechuanaland border, but although the Transvaal Geological Survey has described an occurrence in the Pietersburg district, the source of these fragments for some time remained unknown. However, last year I received from the Rhodesian side of the border, close to Rhodes' Drift on the Limpopo, and north-ward from the well-known Messina copper-mine, some rocks which included large pieces of a type rich in corundum. The area is known to comprise gneissose granulites, consisting of the contact zone and marginal modifications of a granite mass, and the specimens received included large cleavage fragments of felspar and pieces of coarse granite.