Mica Schist

Physical Properties

Hardness: 2-2.5 (for mica layers). Color: Silver-grey, pearly to metallic. Luster: Vitreous to pearly. Structure: Foliated with distinct layers of mica flakes. Cleavage: Perfect basal cleavage in individual grains.

Formation & Geological History

Formed through the regional metamorphism of shale or clay-rich sedimentary rocks under intermediate temperature and pressure. It originates in mountainous regions where tectonic plates collide.

Uses & Applications

Historically used for insulation in electrical equipment due to mica's dielectric properties. Use in construction as decorative stone or in 'glitter' coatings. Highly valued by educators for demonstrating foliation.

Geological Facts

The word 'schist' comes from the Greek 'schistos' meaning 'split', referring to the ease with which it can be split along the mica layers. It is transitional between phyllite and gneiss.

Field Identification & Locations

Identify by its 'sparkly' or 'glittery' appearance and its tendency to flake off in thin, shiny scales when scratched. Common in regional metamorphic belts like the Appalachians or the Alps.

Identified on: 4/13/2026

Mode: Standard