metamorphic
Schist
Mica Schist
Hardness (Mohs scale): 3.5–4; Color: Grey, silver, or black with occasional brown streaks; Luster: Pearly to sub-metallic; Crystal structure: Foliated (schistosity); Cleavage: Excellent in one direction; Specific gravity: 2.7–2.8
- Color
- Grey, silver, or black with occasional brown streaks
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness (Mohs scale): 3.5–4; Color: Grey, silver, or black with occasional brown streaks; Luster: Pearly to sub-metallic; Crystal structure: Foliated (schistosity); Cleavage: Excellent in one direction; Specific gravity: 2.7–2.8
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under high pressure and temperature conditions, typically during mountain-building events.
Uses & applications
Used back in history for building materials and flagstones; today mainly used as decorative garden stone, in landscaping, or for high-quality crushed stone.
Geological facts
The word 'schist' is derived from the Greek word 'schizein', meaning 'to split', referring to the ease with which the rock can be layered or split along its mineral planes.
Field identification & locations
Identify in the field by its distinct 'platiness' or flaky layers and the sparkly reflection of mica flakes. Common in crystalline basement rocks of ancient mountain ranges.
