metamorphic

Schist

Mica schist, typically quartz–muscovite/biotite schist

AI-generated identification · may be incorrect

Usually gray to silvery, with a foliated, flaky texture and sparkly mica luster; individual minerals are commonly Mohs 2–7, while the rock’s effective hardness is variable. Visible foliation and platy mica layers are diagnostic; cleavage follows mica sheets.

Identified September 14, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or another clay-rich sediment is subjected to regional metamorphism, commonly during mountain building, at roughly 300–650°C and moderate pressure. Its exact age cannot be determined from the photograph and may range from Precambrian to younger.

Uses & applications

Used locally as decorative stone, landscaping rock, wall stone, and occasionally aggregate; attractive mica-rich pieces are collected, but it is rarely a high-value gemstone material.

Geological facts

Schistosity develops as mica and other platy minerals recrystallize and align under directed pressure. Quartz-rich varieties can resemble gneiss, slate, or phyllite depending on grain size and foliation strength.

Field identification & locations

Common in metamorphic belts worldwide, including the Appalachians, Alps, Himalaya, and New England. Identify it by wavy foliation, glittering mica flakes, and splitting along aligned layers; confirm composition with a hand lens or thin section.