Mica Schist

Physical Properties

Hardness: 2-3 (on Mohs scale for the mica minerals); Color: Silvery-grey to brownish; Luster: Pearly to metallic; Structure: Foliated with visible mineral grains; Cleavage: Perfect basal cleavage in mica flakes; Specific Gravity: 2.7-3.0

Formation & Geological History

Formed through the regional metamorphism of shale or mudstone under intermediate to high temperatures and pressures. This process aligns mineral grains into parallel layers, creating a schistose texture.

Uses & Applications

Used historically as a building stone (flagstone) and decorative garden stone. Ground mica is used as a filler in construction materials, paints, and cosmetics for its glittery appearance.

Geological Facts

The word 'schist' is derived from the Greek word 'schizein', meaning 'to split', referring to how easily the rock can be cleaved along its foliation planes. It is the intermediate stage between phyllite and gneiss.

Field Identification & Locations

Identify in the field by its strong foliation (schistosity) and 'sparkly' appearance caused by large, visible flakes of mica. It is commonly found in mountain ranges such as the Appalachians or Alps.

Identified on: 4/20/2026

Mode: Standard