Iron Bort

Abstract

WE have been getting occasional pieces of a curious material from the diamond mines, which may prove to have a relation to the mineral described in NATURE of September 7 (J. R. Sutton, “A New Mineral?”), and also may throw some light ultimately upon the origin of the diamond. To outside appearance, in extreme cases, the material has a cindery look; in less extreme cases its diamond affinities are fairly evident. It can be readily disintegrated with a mineralogical file, but it has hard corners which will scratch corundum. The specific gravity is 3.3 to 3.5, i.e. slightly lighter than diamond. It is insoluble in acid, is feebly magnetic, and when suspended by a light thread or floated on water (on a cork) shows distinct polarity under the influence of an ordinary large steel horse-shoe magnet. When it is crushed a small bar magnet will readily take up small specks of it. (The mineral previously described in NATURE, by the way, shows no polarity.)