metamorphic
Schist
Mica Schist
Hardness: 3.5 - 4 (on Mohs scale); Color: Silvery-gray, brownish-red, metallic sheen; Luster: Pearly to metallic; Structure: Foliated with visible mica flakes; Cleavage: Perfect basal cleavage in individual mica grains; Specific gravity: 2.7 - 2.8.
- Hardness
- 3
- Color
- Silvery-gray, brownish-red, metallic sheen
- Luster
- Pearly to metallic
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Physical properties
Hardness: 3.5 - 4 (on Mohs scale); Color: Silvery-gray, brownish-red, metallic sheen; Luster: Pearly to metallic; Structure: Foliated with visible mica flakes; Cleavage: Perfect basal cleavage in individual mica grains; Specific gravity: 2.7 - 2.8.
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under intermediate to high pressure and temperature. The mica flakes align perpendicularly to the direction of pressure, creating a 'schistose' texture.
Uses & applications
Primarily used as a decorative stone in construction for flagstones, tiles, and landscaping. Historically used for roofing slates in some regions. Occasionally used as a host rock for semi-precious gems.
Geological facts
The word 'schist' is derived from the Greek word 'schizein,' meaning 'to split,' referring to how easily the rock can be parted along its foliated layers. Its presence often indicates a significant tectonic event in the geological past.
Field identification & locations
Identify it by its distinct 'shimmer' or 'glitter' when rotated in sunlight and its layered, flaky appearance. It is commonly found in mountain ranges such as the Appalachians, Alps, and Himalayas.
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