THE PREPARATION OF HIGH PERFORMANCE COMPOSITE MICAPOLYMER MATERIAL. IN ONE SYSTEM POLYSTYRENE IS COATED ONTO MICA FLAKES HAVING A HIGH ASPECT RATIO OF AT LEAST ABOUT 20, AND PREFERABLY IN THE RANGE OF 50 TO 100 OR HIGHER. THE MICA FLAKES ARE COATED WITH THE POLYMER BY IN SITU POLYMERIZATION ONTO THE MICA PARTICLES IN SUSPENSION. VARIOUS ADDITIVE MATERIALS MAY BE EMPLOYED TO ENHANCE THE EFFICIENCY OF THE IN SITU COATING STEP. FOR EXAMPLE, A SILANE COUPLING AGENT MAY BE ADDED TO AN AQUEOUS SLURRY OF THE MICA PARTICLES. AS ANOTHER EXAMPLE A COPOLYMERIZABLE MONOMER SUCH AS DIMETHYLAMINOETHYLMETHACRYLATE (DMAEMA) MAY BE ADDED. THE COATED MICA PARTICLES ARE FILTERED AND THE RESULTANT COMPOSITE POWDER IS USEFUL FOR THE MOLDING OF HIGH PERFORMANCE COMPOSITE PARTICLES.