The Magnetic Separation of Heavy Minerals in the Field

Abstract

FOR some time I have been trying to find a simple and rapid field method of separating the magnetic and faintly magnetic from the non-magnetic minerals in the residue obtained by panning a river sand or gravel. In the laboratory this is usually done by means of the electromagnet. I have experimented in the field with a portable electromagnet, but, apart from the disadvantages of weight, bulk, and clumsiness of manipulation, the dynamo is readily liable to go out of order and render the whole apparatus useless. My colleague, Mr. Longbottom, has experimented with a compound magnet composed of three or four simple horseshoe magnets bound together and fitted with adjustable poles. This gives admirable results, and is to be recommended for fractional separations, but the constant adjusting and re-adjusting of the poles becomes tedious in actual practice.