Muscovite, the most common type of mica, is used for a variety of purposes, including in paints, cosmetics, construction materials and electronics. Before humans discovered how to make glass from quartz, most glass was made from thin sheets of muscovite, although this glass was not fully transparent.
Muscovite has a very shiny, pearlescent luster, which is why ground muscovite is used to add a glittery look to cosmetics and paints. Sheets of muscovite mica also have very good insulating properties, so it is very commonly used in the construction of both building materials and electronic components. The crystalline structure of muscovite allows it to cleave into thin, uniform sheets that enable it to be used as window panes. However, there are only a few muscovite deposits in Eastern Europe and India that contain large enough crystals to be suitable for windows.
Muscovite is the only common mineral that can be perfectly cleaved into even, transparent sheets, making it quite easy to identify. It is one of the most common rock-forming minerals and can be found in sedimentary, igneous and metamorphic rocks. Muscovite is especially common in rocks of granitic origin and is only very rarely found in mafic igneous rocks.