metamorphic
Quartz Mica Schist
Mica-Quartz Schist (Chemical: SiO2 + KAl2(AlSi3O10)(OH)2)
Hardness: 6-7 (quartz parts) / 2-2.5 (mica parts); Color: Silvery-gray, white, and translucent; Luster: Pearly to Vitreous; Crystal Structure: Monoclinic/Trigonal (foliated); Cleavage: Perfect basal on mica grains.
- Hardness
- 6-7 (quartz parts) / 2-2
- Color
- Silvery-gray, white, and translucent
- Luster
- Pearly to Vitreous
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Physical properties
Hardness: 6-7 (quartz parts) / 2-2.5 (mica parts); Color: Silvery-gray, white, and translucent; Luster: Pearly to Vitreous; Crystal Structure: Monoclinic/Trigonal (foliated); Cleavage: Perfect basal on mica grains.
Formation & geological history
Formed through the regional metamorphism of clay-rich sedimentary rocks (like shale) under medium-grade pressure and temperature conditions. It typically occurs in mountain belts.
Uses & applications
Used primarily as decorative stone, flagstone for walkways, and sometimes in the manufacturing of heat-resistant materials or cosmetics if mica content is high.
Geological facts
Schist is defined by its 'schistosity,' which is the alignment of platy minerals like mica that allow the rock to split into thin layers. This specific specimen shows massive quartz veins intermixed with foliated mica.
Field identification & locations
Identify by looking for a 'glittery' or 'shiny' appearance caused by mica flakes and a layered (foliated) texture. It is extremely common in metamorphic terrains such as the Appalachian or Alpine mountains.
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