Rock Identifier
Mica-rich schist (Muscovite–biotite quartz schist, composition variable) — metamorphic
metamorphic

Mica-rich schist

Muscovite–biotite quartz schist, composition variable

AI-generated identification · may be incorrect

Typically gray to silvery, with glittering platy mica and uneven foliation; quartz gives a glassy luster. Hardness is about 2–3 for mica and 7 for quartz; specific gravity commonly 2.6–2.8, with no consistent cleavage for the whole rock but excellent mica cleavage.

Identified More metamorphic
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Physical properties

Typically gray to silvery, with glittering platy mica and uneven foliation; quartz gives a glassy luster. Hardness is about 2–3 for mica and 7 for quartz; specific gravity commonly 2.6–2.8, with no consistent cleavage for the whole rock but excellent mica cleavage.

Formation & geological history

Formed when shale or other clay-rich sediment was subjected to moderate heat and pressure during regional metamorphism, commonly during mountain building. Its exact geological age cannot be determined from the photograph.

Uses & applications

Used locally as decorative stone, landscaping material, and occasionally wall or roofing stone; most specimens have modest collector value.

Geological facts

The visible sparkle comes from mica flakes reflecting light, while the layered texture records directed metamorphic pressure. Schist commonly represents a metamorphic grade higher than slate or phyllite.

Field identification & locations

Identify it by its strongly foliated, flaky texture and mica sparkle; it may split along wavy layers and is softer than granite. Common in metamorphic mountain belts worldwide, including the Appalachians, Alps, and Himalayas.