Mica is the general name of mica group minerals. It is the aluminosilicate of potassium, aluminum, magnesium, iron, lithium and other metals, all of which are layered and monoclinic. The crystal is pseudohexagonal lamellae or plate like, occasionally columnar. The lamellar cleavage is very complete, with glass luster and elastic sheet. The refractive index of mica increases with the increase of iron content, from low protrusion to medium protrusion. The variety without iron is colorless in the flake. The higher the iron content, the darker the color, and the more polychromatic and absorptive.

Mica ore mainly includes biotite, phlogopite, muscovite, lepidolite, sericite, chloritite, ferro lepidolite and so on, and placer is a mixed mineral of mica and quartz. Muscovite and phlogopite are the most widely used minerals in industry, and lepidolite is an important mineral raw material for extracting lithium.

Mica group minerals can be divided into three subgroups according to their chemical composition and optical characteristics, including muscovite, biotite phlogopite and lepidolite.

Mica ore widely exists in Asia, Africa and America, but it is rare in Europe. Until the 19th century, the value of mica in Europe was still very high. With the colonists mining mica in Africa and South America, the price dropped rapidly.

Mica Block Mica has very high insulation and heat insulation performance, good chemical stability, strong acid resistance, strong alkali resistance and compression resistance, so it is an important raw material for manufacturing electrical equipment, so it can also be used as the insulation material in the blower. Mica has birefringence at the same time, so it is also an optical instrument material for manufacturing polarized light sheet. Mica mining used in the electrical industry must be mica blocks with an effective area of more than 4 square centimeters, free of cracks and holes, and non mica minerals on the edge shall not exceed 3 mm. After mica mining, the quality is divided into four categories according to the effective area, and the best special category area is greater than 65 square centimeters.

Muscovite is widely used in industry, followed by phlogopite. It is widely used in building materials industry, fire fighting industry, fire extinguishing agent, welding rod, plastic, electrical insulation, paper making, asphalt paper, rubber, pearlescent pigment and other chemical industries. [2]