metamorphic
Schist (Micaceous)
Mica Schist (predominantly Muscovite or Biotite)
Hardness: 3.5-4; Color: Silver, gray, brown, or goldish due to mica and iron staining; Luster: Pearly to sub-metallic; Crystal structure: Foliated (schistosity); Cleavage: Perfect in one direction on mica flakes; Specific gravity: 2.7-2.8
- Hardness
- 3
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness: 3.5-4; Color: Silver, gray, brown, or goldish due to mica and iron staining; Luster: Pearly to sub-metallic; Crystal structure: Foliated (schistosity); Cleavage: Perfect in one direction on mica flakes; Specific gravity: 2.7-2.8
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under intermediate pressure and high temperature. Often associated with Precambrian to Paleozoic mountain-building events.
Uses & applications
Used primarily as decorative stone, construction aggregate, and occasionally as a source for ground mica in insulation or cosmetics. Often used in landscaping and flagstone.
Geological facts
The word schist is derived from the Greek 'schistos', meaning 'split', referring to the ease with which it can be layered. It is an intermediate grade of metamorphism between phyllite and gneiss.
Field identification & locations
Identify by its shiny, platy layers (foliation) that spark in the sun. It is extremely common in metamorphic belts like the Appalachians (USA), the Alps, and Scandinavia.
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