metamorphic
Muscovite Schist
Mica Schist (KAl2(AlSi3O10)(OH)2)
Hardness: 2-2.5 (mica layers), Color: Silvery-gray to brownish, Luster: Pearly to metallic (vitreous), Crystal structure: Monoclinic (foliated), Cleavage: Perfect basal cleavage, Specific gravity: 2.76-3.0
- Hardness
- 2-2
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Physical properties
Hardness: 2-2.5 (mica layers), Color: Silvery-gray to brownish, Luster: Pearly to metallic (vitreous), Crystal structure: Monoclinic (foliated), Cleavage: Perfect basal cleavage, Specific gravity: 2.76-3.0
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under medium-grade pressure and heat. It is characterized by the alignment of mica flakes, creating a schistose texture.
Uses & applications
Used as a source of scrap mica for electrical insulation, drywall joint compounds, paint fillers, and pearlescent pigments in cosmetics.
Geological facts
The word 'schist' is derived from the Greek word 'schistos', meaning 'split', referring to the ease with which the rock can be cleaved along its foliated planes.
Field identification & locations
Identify in the field by its distinct 'glittery' or sparkly appearance and its layered, flaky texture. Commonly found in mountain belts such as the Appalachians or the Alps.
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