metamorphic
Schist
Mica Schist (primarily consisting of muscovite, biotite, and quartz)
Hardness: 3.5 - 4 on Mohs scale; Color: Silvery-gray, bluish-gray, or green; Luster: Pearly to sub-metallic; Structure: Foliated with visible mineral grains (schistosity); Cleavage: Perfect in one direction along mica flakes; Specific Gravity: 2.7 - 3.0.
- Hardness
- 3
- Color
- Silvery-gray, bluish-gray, or green
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness: 3.5 - 4 on Mohs scale; Color: Silvery-gray, bluish-gray, or green; Luster: Pearly to sub-metallic; Structure: Foliated with visible mineral grains (schistosity); Cleavage: Perfect in one direction along mica flakes; Specific Gravity: 2.7 - 3.0.
Formation & geological history
Formed through the regional metamorphism of shale or mudstone at intermediate temperatures and pressures. This transformation typically occurs during mountain-building events (orogenies) over millions of years.
Uses & applications
Used historically as a building stone, for decorative flagstones, and in the manufacturing of electrical insulators (due to mica content). It is also a popular specimen for educational geology kits.
Geological facts
The word 'schist' comes from the Greek word 'schizein', meaning 'to split', referring to the stone's tendency to peel into thin layers. It is the parent material for many high-grade metamorphic rocks like gneiss.
Field identification & locations
Identify by its 'schistosity'—the alignment of platy mica minerals that catch the light and create a shimmering effect. In the field, it is often found in the roots of eroded mountain ranges or along tectonic plate boundaries.
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