Natural mica will undergo hydration reaction under the long-term scouring of high temperature and high pressure water to make mica discolor, stratification, scale, wet and even rupture. Natural muscovite has a tendency to lose weight from 200 ° C. When the temperature is higher than 450 ° C, it begins to decompose, the thickness expands, and the weight loss is above 600 ° C, and it almost completely decomposes at 900 ° C.

 

         The phlogopite starts to decompose from 500 ° C, and the weight loss is remarkable at 900 ° C or above. The specific performance of its weight loss is gradually starting from 200 ° C, discoloration, and shedding. Therefore, the use temperature of natural mica is limited. For ultraviolet light, natural mica is basically impermeable, and natural muscovite has a distinct absorption peak at 2.75 microns (wavenumber 3636 cm-1).