Known also as Common Mica or Isinglass is a common mineral found in igneous, metamorphic and sedimentary rocks. Muscovite occurs in a variety of brown, gray, yellow and smoky green colors but can also be found in transparent and translucent forms.
Muscovite is used for a range of commercial applications as the mineral forms in natural sheets and is an excellent insulator of electricity and heat. Cleaved into super thin sheets, muscovite has been used for lining the viewing windows of industrial furnaces and also for lining the viewing doors of old microwave ovens.
The name muscovite derives from the term Muscovy-glass as sheets of this minerals have been used as windows in Russia. The base of this names come from the Latin word "micare" which means "to shine".
Muscovite has a Mohs hardness of 2-2.25.
A sheet of muscovite is on display in the Science Alcove in the Science Library at MOSI.