Abstract: A method and apparatus for separating from a mixture materials having different specific gravities which can operate in a continuous manner and can separate particles of materials of non-uniform grain size. Water or other fluid is passed upwardly through an apparatus having an upper funnel in which is disposed a rotatable agitator having vanes or paddles which pass close to riffles on the wall of the funnel. Material to be separated is fed into the funnel and the upward flow of fluid is adjusted so that material of low specific gravity is carried up the funnel to an overflow discharge. With the agitator rotating, fine particles of the material to be separated and having a specific gravity higher than a certain figure are captured in "dead-zones" created behind the riffles and move down through the fluid to a discharge tube. Larger particles of the material to be separated move down through the upward flow of fluid to the discharge tube.