metamorphic
Schist
Mica Schist
Hardness: 3.5-4; Color: Grey, silver, greenish-grey; Luster: Pearly to sub-metallic due to mica content; Crystal structure: Foliated (schistosity); Cleavage: Perfect basal cleavage in individual mica grains.
- Hardness
- 3
- Color
- Grey, silver, greenish-grey
- Luster
- Pearly to sub-metallic due to mica content
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Physical properties
Hardness: 3.5-4; Color: Grey, silver, greenish-grey; Luster: Pearly to sub-metallic due to mica content; Crystal structure: Foliated (schistosity); Cleavage: Perfect basal cleavage in individual mica grains.
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under intermediate to high grades of pressure and temperature. Most are associated with major mountain-building events (orogenies).
Uses & applications
Used occasionally as a decorative stone in landscape architecture, building veneer, and crushed stone for road construction. Not suitable for heavy structural use due to splitting along planes.
Geological facts
The word 'schist' is derived from the Greek word 'schizein', which means 'to split'. This refers to the rock's tendency to split easily along the planes of its mineral grains.
Field identification & locations
Identify in the field by its distinct 'shimmer' when held in the light and its tendency to flake into thin sheets. It is commonly found in the Appalachian Mountains, the Scottish Highlands, and the Alps.
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