metamorphic
Mica Schist with Quartz
Mica Schist (Quartz-Muscovite Schist)
Hardness: 2.5-3 for mica layers, 7 for quartz grains; Color: Silvery-grey to brownish-tan with highly reflective metallic sparkles; Luster: Vitreous to pearly/silky; Structure: Foliated schistose texture with visible flakes of muscovite and quartz aggregates.
- Hardness
- 2
- Luster
- Vitreous to pearly/silky
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Physical properties
Hardness: 2.5-3 for mica layers, 7 for quartz grains; Color: Silvery-grey to brownish-tan with highly reflective metallic sparkles; Luster: Vitreous to pearly/silky; Structure: Foliated schistose texture with visible flakes of muscovite and quartz aggregates.
Formation & geological history
Formed by regional metamorphism of clay-rich sedimentary rocks such as shale or mudstone under moderate temperatures and pressures (medium-grade metamorphism). Common in mountain-building belts worldwide.
Uses & applications
Used occasionally as a decorative building stone or flagstone (when durable enough), but mostly collected as an educational rock specimen or used in geological studies.
Geological facts
The characteristic sparkle of mica schist is due to the parallel alignment of shiny muscovite or biotite mica flakes, which align perpendicular to the direction of maximum stress during tectonic forces.
Field identification & locations
Identified in the field by its pronounced foliation, flakey metallic mica layers that easily peel with a knife, and sparkling reflective surfaces. Commonly found in metamorphic terranes like the Appalachian Mountains, Alps, and Scottish Highlands.
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