A new class of injection-moldable reinforced thermoplastics that utilizes flake reinforcement, instead of fibrous reinforcement, has been developed. It is found that a suitably prepared grade of mica can be used to reinforce ABS, SAN, and Nylon 6/6. The moduli of these new compounds are much higher than existing glass-fiber RTP, the strengths are comparable, the impact strengths somewhat lower. Ternary composites of mica, glass-fiber, and thermoplastic have also been produced. These have improved impact strengths but somewhat lower moduli compared to the mica only composites.