mus·co·vite 
(mŭskə-vīt′)
(mŭskə-vīt′)n.
A potassium aluminum silicate mineral, KAl2(AlSi3O10)(OH)2, the most common form of mica, which ranges from colorless or pale yellow to gray and brown, has a pearly luster, and is used as an insulator. Also called white mica.
[Muscovy glass, its former name + -ITE1.]