metamorphic
Mica Schist
Mica Schist (primarily Muscovite and Biotite KAl2(AlSi3O10)(OH)2)
Hardness: 2-2.5 on Mohs scale; Color: Silver, grey, or black with a metallic sheen; Luster: Pearly to silvery-metallic; Crystal structure: Monoclinic with perfect basal cleavage; Specific gravity: 2.7–3.0
- Hardness
- 2-2
- Color
- Silver, grey, or black with a metallic sheen
- Luster
- Pearly to silvery-metallic
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Physical properties
Hardness: 2-2.5 on Mohs scale; Color: Silver, grey, or black with a metallic sheen; Luster: Pearly to silvery-metallic; Crystal structure: Monoclinic with perfect basal cleavage; Specific gravity: 2.7–3.0
Formation & geological history
Formed through the regional metamorphism of shale or clay-rich sedimentary rocks under high temperature and pressure, causing the growth of large, visible mica flakes aligned perpendicularly to pressure.
Uses & applications
Used primarily for decorative landscaping, as a source of industrial mica (fillers, insulators), and in various cosmetics for its reflective properties.
Geological facts
The term schist is derived from the Greek word 'schistos', meaning 'split', referring to the ease with which it can be split into thin, flat plates. It is characterized by having more than 50 percent platy minerals.
Field identification & locations
Identify in the field by its distinct 'schistosity' or foliated layering and its highly reflective, sparkly appearance when held up to the light. It is common in mountain ranges and metamorphic belts worldwide.
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