Mica is a rock-forming mineral in the earth's crust, and is a general term for a group of minerals. Mica group minerals are aluminosilicate ore with complex chemical composition, the main elements include potassium, sodium, magnesium, iron and lithium in addition to silicon, aluminum and oxygen. In addition, natural mica group minerals are more common in the  isomorphous of homogeneous substitution and contain other minor elements such as manganese, titanium, gallium, barium, sulfur, etc.