Mica Schist with Garnet

Physical Properties

Hardness: 6-7.5 (Garnet crystals), 2-3 (Mica matrix); Color: Silvery-gray, brownish-green with dark red/black spots; Luster: Pearly to Vitreous; Crystal structure: Monoclinic and Isometric grains; Cleavage: Perfect basal cleavage in mica; Specific gravity: 2.8-3.2

Formation & Geological History

Formed through the regional metamorphism of clay-rich sedimentary rocks (pelites) under intermediate to high temperatures and pressures. Most common in mountain-building belts from various geological ages.

Uses & Applications

Primarily used as a decorative stone, in construction as fill or base material, and occasionally processed for garnet abrasives used in waterjet cutting.

Geological Facts

The presence of garnet in schist is a geological indicator of the intense pressure and temperature conditions the rock endured during the formation of mountain chains like the Appalachians or Himalayas.

Field Identification & Locations

Identify by its 'schistose' texture (layered appearance) and the sparkling, flaky mica grains. Often found in metamorphic terrains such as parts of New England or the Blue Ridge Mountains.

Identified on: 5/3/2026

Mode: Standard