metamorphic
Mica Schist
Foliated Metamorphic Rock (rich in Muscovite or Biotite)
Hardness: 2-4 (variable); Color: Silvery-gray, charcoal, or brown with a sparkly sheen; Luster: Pearly to sub-metallic; Crystal structure: Platy/foliated; Cleavage: Excellent in one direction (mica flakes); Specific Gravity: 2.7-3.0
- Hardness
- 2-4 (variable)
- Color
- Silvery-gray, charcoal, or brown with a sparkly sheen
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness: 2-4 (variable); Color: Silvery-gray, charcoal, or brown with a sparkly sheen; Luster: Pearly to sub-metallic; Crystal structure: Platy/foliated; Cleavage: Excellent in one direction (mica flakes); Specific Gravity: 2.7-3.0
Formation & geological history
Formed through the regional metamorphism of clay-rich sedimentary rocks (shale or mudstone) under intermediate temperatures and pressures. Most were formed during ancient mountain-building events (Orogenies).
Uses & applications
Historically used for roofing and paving, though currently mostly of interest for geological study and mineral collecting. Occasionally used as a filler in construction materials or as an ornamental stone.
Geological facts
The word 'schist' comes from the Greek word 'schistos', meaning 'split'. This refers to the rock's tendency to split into thin sheets due to its high mica content.
Field identification & locations
Identify by its sparkly, 'glittery' appearance and visible alignment of mineral grains (foliation). It feels rough and may flake off in your hands. Commonly found in metamorphic belts like the Appalachians, Alps, or Himalayas.
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