Abstract: This application concerns the separation of fine granular mixtures that may occur when the grains are suitably vibrated within fluid. In particular, the present invention provides a method of separating a particulate mixture comprising different particle types, comprising subjecting a supported particle bed comprising a fluid and said particulate mixture to a vibration thereby to effect separation of the particulate mixture into strata each of which is preferentially rich in substantially one particle type. Apparatus for effecting the above method also provided.