Garnet Schist

Physical Properties

Hardness: 6.5-7.5 (garnets) vs 2-3 (mica matrix); Color: Silver-grey matrix with reddish-brown crystals; Luster: Pearly to sub-metallic (matrix), Vitreous (garnets); Foliated texture; Specific Gravity: 2.8-4.3.

Formation & Geological History

Formed through the regional metamorphism of shale or mudstone under high pressure and temperature. The garnets grow as porphyroblasts within the foliated mica-rich matrix.

Uses & Applications

Predominantly used as a geological educational specimen. Industrial-grade garnets can be used as abrasives in waterjet cutting and sandblasting.

Geological Facts

The garnets in these rocks are often 'almandine', the most common member of the garnet group. Schist is characterized by having more than 50% platy and elongated minerals.

Field Identification & Locations

Identify by looking for 'sparkly' or 'shimmery' layers (foliation) containing distinct, rounded, reddish crystals. Found in mountain ranges like the Appalachians, Alps, or Himalayas.

Identified on: 4/18/2026

Mode: Standard