Mica Schist

Physical Properties

Hardness: 3.5–4 on the Mohs scale; Color: Silver, gray, brown, to golden-bronze; Luster: Pearly to metallic; Structure: Foliated with visible flakes; Cleavage: Excellent basal cleavage in mica components.

Formation & Geological History

Formed from the metamorphism of shale or mudstone under medium-grade pressure and temperature conditions (regional metamorphism). The mica crystals grow perpendicular to the direction of pressure, creating the characteristic 'schistosity'.

Uses & Applications

Used historically as a building stone, decorative garden stone, and occasionally for ground mica in industrial lubricants or as a filler in construction materials.

Geological Facts

Mica schist is known for its 'shimmer' or 'sparkle' even in low light. It often contains garnets (porphyroblasts) which can be found as hard, dark red nodules within the foliation layers.

Field Identification & Locations

Identify in the field by its distinct layered (foliated) appearance and the high amount of reflective mica flakes that rub off on hands. Commonly found in mountain ranges and metamorphic belts.

Identified on: 4/5/2026

Mode: Standard