Abstract: Apparatus for removing heavy material from ore in a water environment includes an upstanding tube, a reservoir, and a pulsator connected between the upstanding tube and the reservoir. The pulsator cyclically causes the upstanding tube to move downward, and fluid pressure within reservoir causes it to move back upward. This vertical pulsation of the upstanding tube effects the separation of heavy material from lighter material contained within the ore. The pulsator includes a member and diaphragm which are cyclically forced downward into the reservoir by a cam-driven rocker arm. A given downward movement of the member and diaphragm results in an amplified upward movement of the ore and the water within the upstanding tube.