Mineral Guide · Mineral group or series
Mica is a group of sheet silicate minerals known for flexible or brittle cleavage into thin, shimmering sheets.
Mica is the name for a group of sheet silicate minerals rather than one mineral species with a single fixed formula. Common members include muscovite, biotite, phlogopite and lepidolite, each with its own chemistry and details.
Mica minerals have layered crystal structures that allow them to split into thin sheets. Cleavage surfaces are often pearly or vitreous and may show a characteristic shimmer. Colours range from colourless and silvery through brown, black, green, lilac and pale yellow, depending on the mica species and its chemistry.
Micas occur in igneous, metamorphic and hydrothermal rocks. They are common in granites, pegmatites, schists and marbles. Muscovite and other mica-group minerals are found in mineral localities worldwide, with important collector material from Brazil, Russia, India, Madagascar, Pakistan, the United States and many European regions.
Mica is valued for reflective flakes, thin translucent sheets and natural colour. In a mineral specimen or mosaic composition, the exact species and locality should be recorded whenever known. Because mica splits easily along cleavage, thin pieces should be supported and protected from bending or impact.
Reviewed by NotOnlyRocks Editorial Team
Last reviewed: 20 August 2026