Muscovite is a member of the mica group of silicate minerals (sheet silicates) in which the base of all of the SiO 4 tetrahedra lie in one plane and three corners of the base are shared with the neighbouring tetrahedra. This creates a strongly layered sheet-like structure, hence the term sheet silicate (the sheets are weakly bound together by layers of potassium ions). Muscovite, biotite and chlorite are all common mica group minerals.

Muscovite is commonly found in metamorphic rocks such as schists and gneisses, sedimentary rocks (as the fine grained variety sericite), and in igneous rocks such as granite.

Although muscovite has perfect cleavage, individual sheets are quite durable and are often found in sands that have undergone erosion and transport that would have destroyed most other minerals. Sheets of muscovite have high heat and electrical insulating properties and are used in the manufacture of many electrical components. Muscovite sheets were used for kitchen oven windows before synthetic materials replaced them.

Chemical composition - KAl 3Si 3O 10(OH) 2
Hardness - 2-2.5
Specific gravity - 2.8
Transparency - Transparent to translucent
Colour - White, silver, yellow, green and brown
Streak - White
Lustre - Vitreous to pearly
Cleavage/fracture - Perfect in one direction producing thin sheets or flakes / uneven
Crystal habit/mode of occurrence - Tabular (sheets or flakes)