In its earlier form, a mineral separator to which the material was fed by a vibrating conveyor and passed through successive zones of magnetic influence. The zones were covered by the rims of rotating disks, which became magnetized, carried the particles having magnetic susceptibility out of the fields, were demagnetized, and dropped the concentrate beyond the edge of the belt. Now made with rollers having an induced magnetism; dried, finely crushed ore passed over the rollers in a thin stream from which particles attracted by the magnet are drawn out.