metamorphic
Mica Schist
Mica Schist (varies based on mineral makeup, often Biotite/Muscovite schist)
Hardness: 3.5-4 on Mohs scale; Color: Dark grey, charcoal, to black with silvery mineral grains; Luster: Sub-metallic to vitreous (pearly/shiny mica flakes); Cleavage: Foliated/schistose (splits along aligned mica sheets); Specific Gravity: 2.7-3.0
- Hardness
- 3
- Color
- Dark grey, charcoal, to black with silvery mineral grains
- Luster
- Sub-metallic to vitreous (pearly/shiny mica flakes)
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Physical properties
Hardness: 3.5-4 on Mohs scale; Color: Dark grey, charcoal, to black with silvery mineral grains; Luster: Sub-metallic to vitreous (pearly/shiny mica flakes); Cleavage: Foliated/schistose (splits along aligned mica sheets); Specific Gravity: 2.7-3.0
Formation & geological history
Formed through regional metamorphism of shale, mudstone, or clay-rich sedimentary rocks under moderate temperatures and pressures (medium-grade metamorphism). Often associated with mountain-building events.
Uses & applications
Occasionally used as dimension stone, flagstone, decorative landscaping rock, and as an aggregate in construction. High-grade specimens are collected for educational and study purposes.
Geological facts
Schist is characterized by having medium to coarse-grained flaky minerals (like mica) aligned in parallel layers, a texture known as schistosity. Highly shiny mica flakes often reflect light intensely when tilted.
Field identification & locations
Look for prominent parallel layers of shiny, flaky mica minerals that give the rock a silvery or sparkly dark appearance and cause it to break along preferential planes. Found widely in mountain belts globally, such as the Appalachians and the Alps.
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