Muscovite Mica

Physical Properties

Hardness: 2-2.5 on Mohs scale; Color: Colorless, silvery-white, or pale yellowish; Luster: Pearly to vitreous; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin sheets); Specific Gravity: 2.76-3.00

Formation & Geological History

Formed in igneous environments (granites and pegmatites) and metamorphic rocks (schists and gneisses). Occurs worldwide in mountain belts and continental shield areas.

Uses & Applications

Used as an electrical insulator in capacitors, as a filler in paints and plastics, as a shimmering agent in cosmetics (glitter), and in high-temperature furnace windows.

Geological Facts

Muscovite was historically known as 'Muscovy glass' because it was used as a cheaper, more durable alternative to glass for windows in Russia. It can withstand extreme temperatures without melting.

Field Identification & Locations

Identify in the field by its 'book' like structure and the ability to peel off very thin, flexible, transparent flakes with a fingernail. Commonly found in sparkling outcrops of granite.

Identified on: 5/16/2026

Mode: Standard