Mica Schist

Physical Properties

Hardness: 3.5-4 on Mohs scale; Color: Silver-grey to brownish; Luster: Pearly to metallic; Crystal structure: Monoclinic; Cleavage: Perfect basal cleavage in individual grains; Specific gravity: 2.7-3.0

Formation & Geological History

Formed through the regional metamorphism of shale or mudstone under medium-grade heat and pressure. This process causes clay minerals to recrystallize into large, visible plate-like mica minerals.

Uses & Applications

Historical use in hearths and stone walls. Today, Schist is sometimes used as a decorative stone for gardening, walkways, and occasionally as a source for graphite or garnets which frequently grow within it.

Geological Facts

The word 'schist' is derived from the Greek word 'schizein', meaning 'to split', referring to the rock's tendency to split easily along the planes of its mica flakes, a property known as schistosity.

Field Identification & Locations

Identify in the field by its distinct 'shimmer' or 'sparkle' when rotated in sunlight. It has a foliated texture where the mica flakes are aligned. Commonly found in mountain ranges like the Appalachians, Alps, and Himalayas.

Identified on: 4/27/2026

Mode: Standard