Mica has been recognized as a unique inorganic Plastic filler because of its exceptional properties not found in any other filters. Mica has outstanding mechanical, thermal, electrical and chemical properties rarely found in any other fillers.  Mica is chemically inert and can resist heat, water, oil, solvents, and various chemicals. Addition of mica improves stiffness and high temperature performance, but due to structure of the mineral, it provides even more of a boost to these properties of the base polymer.