Abstract
The crystal size is able to calculate according to diffraction degrees and diffraction beam width of X rays. The thickness of the refinement Na tetrasilisic mica crystal in suspension was 27A (2.8 layers). The particle diameter of this sample measured by laser diffractometer is 9.8um. The aspect ratio of Na tetrasilisic mica became 3,600. Such a high aspect ratio particle is useful as barrier filler.