X represents large interlayer cations, such as K+, Na+, Ca2+, Ba2+, Rb+, Cs+, etc. Y represents octahedral cations, such as Al3+, Fe2+, Mg2+, Cr3+, Ti4+, Fe3+, etc. Z is mainly Si4+ and Al3+; The ideal ratio of the additional anion (OH)- to (O)2- is 2:10, and (OH)- can be replaced by F- and Cl-. Most mica contain 4% to 5% water. Therefore, although they may be called mica, the chemical composition of different mica may be very different, for the purpose of research, we collectively refer to the minerals with this type of characteristics as mica group minerals.  

Mica has a wide range of uses, in ancient China, it is often used to do traditional Chinese medicine, the ancients even think that taking mica: a year to remove all diseases (heavy metal poisoning), three years of long service, husband into a boy (body scrap), Zhongshan uncle Qing suit, over time can become a cloud (soul ascension). However, in the era without glass, the transparency of mica makes it a better decorative material, for example, we are familiar with the mica screen candle shadow deep, the river gradually falling Xiaoxing sink. Mica screen is low, tassel tent is small and mica calf car.

Natural mica powder and synthetic mica powder also have great differences in electrical insulation, mechanical properties, chemical stability, application range and cost. Natural mica powder has good electrical insulation, but the volume resistivity is lower than that of synthetic mica. Synthetic mica powder has better electrical insulation properties, high volume resistivity and stable dielectric constant, and is suitable for high performance electrical insulation materials. The hardness of natural mica powder is relatively low (2-3), and it has good elasticity and peeling property. The hardness of synthetic mica powder is higher (between 3 and 4), and the tensile strength and compressive strength are better than that of natural mica powder. Natural mica powder is stable in acid-base solution, but it is easy to decompose at high temperature. Synthetic mica powder is stable to acid and base at room temperature, but will be slowly corroded by sulfuric acid above 300℃. Better thermal stability, not easy to release gas. Natural mica powder is widely used in electrical appliances, welding rods, rubber, plastics, paper making, paint and other fields. Synthetic mica powder is mainly used in high-end electrical insulation materials, aviation, aerospace, national defense industry and other high-tech fields. Because synthetic mica powder needs to be produced through complex chemical processes, its production cost is usually higher than that of natural mica powder. Therefore, in the market, the price of synthetic mica powder is often higher than that of natural mica powder. However, with the continuous progress of production technology and the gradual emergence of scale effects, the price of synthetic mica powder is expected to gradually decrease.