Mica group or briefly mica is the term for a group of sheet silicates showing perfect cleavabilty into resilient sheets, whose most significant characteristics are high thermal resistance, chemical inertness, acid-resistance as well as good electrical insulation properties. There are different types of mica, categorized according to their chemical composition, but only muscovite (potassium-aluminium silicate) and phlogopite (manganese-iron-aluminium silicate) are relevant for industrial applications.
In distant past already, mica was used for cosmetic purposes, and it is also applied in decorative cosmetics today. Here, as in many other applications as construction material, in paints, plastics, welding electrodes, casting products or optical applications, ground mica is typically used as a filler material, whereas it primarily serves as a release agent in the rubber industry.
And indeed, the kind of application is decisive as regards mica processing: if the sheet structure of mica must be preserved, the wet grinding method is applied, since dry grinding into flakes or powder will largely destroy the structure.