Mica-rich Schist fragment

Physical Properties

Hardness: 2-2.5 on Mohs scale; Color: Silvery-gray, metallic, green-gray; Luster: Pearly to metallic; Crystal Structure: Monoclinic; Cleavage: Perfect basal (peels into thin flakes).

Formation & Geological History

Formed from the regional metamorphism of clay-rich sedimentary rocks (shales) or igneous rocks under high pressure and temperature. It is commonly found in mountain belts where tectonic plates collide.

Uses & Applications

Used as an insulator in electrical equipment, as a pigment extender in paints, and occasionally in decorative building materials or as a filler in plastic and rubber.

Geological Facts

Mica flakes were historically used as windows in Russian heaters (Muscovy-glass) because they are heat-resistant and transparent when thin.

Field Identification & Locations

Identify in the field by its distinct foliation (schistosity) and the presence of visible, plate-like mineral flakes that glint in the sunlight. Commonly found in eroded metamorphic terrains.

Identified on: 4/14/2026

Mode: Standard