MUSCOVITE was once commonly used for windows. The Russian mica mines that produced it gave muscovite its name (it was once widely known as "Muscovy glass"). Muscovite is is a high-aluminum member of the mica family of minerals, all known for the property of perfect basal cleavage; cleavage layers can be easily peeled off into very thin sheets which are quite durable and are not easily destroyed by erosion. Muscovite sheets have high heat and electrical insulating properties and are used to make electrical components.
A common rock forming mineral, muscovite is found in igneous, metamorphic and detrital sedimentary rocks. It is not usually valuable as a mineral specimen but can be found associated with other valued minerals such as tourmaline, topaz, beryl, almandine
Chemistry: Potassium aluminum silicate hydroxide fluoride ♦ Class: Silicates ♦ Group: micas ♦ Crystal system: monoclinic ♦Luster: vitreous to pearly ♦ Color: white, silver, yellow, green and brown ♦ Transparency: transparent to translucent ♦ Fracture: uneven ♦ Cleavage: perfect in one direction producing thin sheets or flakes ♦ Moh's hardness: 2 - 2.5 ♦ Localities: India, Pakistan, Brazil and many USA localities.