metamorphic
Schist
Mica Schist (Quartz-Muscovite-Biotite Schist)
Hardness: 3.5–4.5 on Mohs scale; Color: Silvery-gray, brownish-yellow, or bronze due to iron staining; Luster: Pearly to sub-metallic; Crystal structure: Foliated (schistose fabric); Cleavage: Excellent in one direction (micaceous); Specific gravity: 2.7–2.8
- Hardness
- 3
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness: 3.5–4.5 on Mohs scale; Color: Silvery-gray, brownish-yellow, or bronze due to iron staining; Luster: Pearly to sub-metallic; Crystal structure: Foliated (schistose fabric); Cleavage: Excellent in one direction (micaceous); Specific gravity: 2.7–2.8
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under medium-grade pressure and temperature conditions. Typically found in the core of mountain belts and ancient crystalline shields.
Uses & applications
Used historically as a building stone (flagstone), decorative stone in landscaping, and sometimes for the extraction of industrial minerals like garnet or graphite contained within the matrix.
Geological facts
The word 'schist' is derived from the Greek word 'schizein', meaning 'to split', referring to how easily the rock can be divided along its platey mineral layers. Schist is often the source of placer gold in many river systems.
Field identification & locations
Identify in the field by its distinct 'schistosity'—a shimmering, layered appearance where the individual mica flakes are visible to the naked eye. It often has a wavy or crinkled texture.
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