Mica

1) The group of muscovites (or common mica, serishm or potash mica) as anisotropic minerals, which are an aluminum and potassium fluosilicate mineral with the chemical formula [KAl2[(OHF)2-AlSi3O10.

The crystals of this group are sub-sheets which usually have elastic ability and their crystallization system is monoclinic and are seen as flexible and resilient scales. The minerals have a specific face and if a blow is made on the surface of the mica group minerals, a six-radial shape is formed. It is insoluble in acids. Other similar minerals are mica.
Muscovite is the most common mica found in granites, pegmatites, gneisses and schists. Muscovites are also known as a contact metamorphic rock or as a secondary mineral material caused by the alteration of topaz, feldspar and kainite.
It has a complex and variable chemical composition and can be seen in green, yellow, white, gray, white colors
The hardness of Muscovite is between 2 and 2.25.
The specific gravity of muscovite is between 2.76 and 3.

Its application: In the electronics industry, it is used to produce insulation, fireproof materials, for insulation and ceramics, and to some extent as a lubricant.
Based on size, mica is divided into two main categories: sheet mica and crushed mica. Mica sheet is suitable for use in electrical works and is used as an insulating sheet in electrical tools and airplane spark plugs, in iron construction, etc.

2) Biotite group: It consists of elements of iron, magnesium, oxygen, hydrogen and silicon, which are placed next to each other by potassium ion with a weak bond. The element of iron in biotite is more than other mica, therefore it is also called iron mica. Biotite has a hardness between 1.5 and 3 and is used in making electrical components.