Mayer's potential energy theory is one of the most widely accepted theories describing jigging. While it represented a substantial contribution to jig theory, the potential energy theory can not be applied directly to describe real jigging operations. A modification to that theory has been made recently and is called the dispersion model of jigging. That model, however, is limited to describing jigging of particles of uniform size. A procedure that uses the Monte Carlo technique and Mayer's principle has been developed, and is used to simulate jigging of particulate mixtures of variable size and density. It is demonstrated that for the case of monosize feeds with variable densities the simulation procedure provides results identical to those from the dispersion model. Further, in the case of binary-sized feeds, it is shown that a layer of fines accumulates in the top of the bed, while a greater proportion of coarse material is observed in the bottom of the bed.