Abstract: New plastic compositions, made from a uniform mixture of thermoplastic resin and a naturally occurring aluminosilicate glass (NOAG) produce articles of manufacture by a variety of molding processes that have a more uniform and smoother surface with significantly reduced sink marks, and exhibit an improved dispersion of additives and pigments. The molding machines making articles from these compositions of thermoplastic resin and NOAG exhibit an increase in throughput, lower operating temperatures, less power consumption, reduced injection pressure, and increased injection speed. Running these synthetic plastic compositions through injection, extrusion and blow molding machines also tends to clean and lubricate the screw and the injector nozzles, increasing the life of the machine parts. The NOAG is preferably present in amounts ranging from 0.1% to 3.0% by weight of the composition.