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Muscovite
Chemical Formula	KAl2(AlSi3O10)(F,OH)2
Species	Silicates
Crystal System	Monoclinic
Mohs Scale	2
Specific Gravity	2.76-3
Color	White, grey, silvery
Streak	White
Luster	Vitreous, Silky, Pearly
Refractive Index	n = 1.552 - 1.576 n = 1.582 - 1.615 n = 1.587 - 1.618
Diaphaneity	Transparent, Translucent
Cleavage	PerfectPerfect on .
Fracture	Micaceous
Crystal Habit：massive to platy
Geological Setting：Muscovite is common in many different rock types as a primary mineral.

Muscovite (also known as common mica, isinglass, or potash mica) is a phyllosilicate mineral of aluminium and potassium with formula KAl₂(AlSi₃O₁₀)(F,OH)₂, or (KF)₂(Al₂O₃)₃(SiO₂)₆(H₂O). It has a highly-perfect basal cleavage yielding remarkably-thin lamin? (sheets) which are often highly elastic. Sheets of muscovite 5×3 m have been found in Nellore, India.

Muscovite has a Mohs hardness of 2–2.25 parallel to the [001] face, 4 perpendicular to the [001] and a specific gravity of 2.76–3. It can be colorless or tinted through grays, browns, greens, yellows, or (rarely) violet or red, and can be transparent or translucent. It is anisotropic and has high birefringence. Its crystal system is monoclinic. The green, chromium-rich variety is called fuchsite; mariposite is also a chromium-rich type of muscovite.

Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic rock or as a secondary mineral resulting from the alteration of topaz, feldspar, kyanite, etc. In pegmatites, it is often found in immense sheets that are commercially valuable. Muscovite is in demand for the manufacture of fireproofing and insulating materials and to some extent as a lubricant.

The name of muscovite comes from Muscovy-glass, a name formerly used for the mineral because of its use in Russia for windows.