The main crystal mica into monoclinic, Crystal was off the six-party thin sheet, scale-like, plate, sometimes to the six-party column was false. 2 to 3 hardness, the proportion of 2.70 to 3.20. The refractive index of mica with higher iron content and the corresponding increase may be lower processes are processes to Chiang Kai-shek. The iron-free variant of thin colorless, the higher iron content, the deeper the color, multicolor and at the same time to absorb