metamorphic
Schist
Mica Schist
Hardness: 3.5-4; Color: Grey, silver, or greenish; Luster: Silky to pearly due to mica content; Crystal Structure: Foliated; Cleavage: Excellent in one direction (slaty/schistose); Specific Gravity: 2.5-2.9
- Hardness
- 3
- Color
- Grey, silver, or greenish
- Luster
- Silky to pearly due to mica content
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Physical properties
Hardness: 3.5-4; Color: Grey, silver, or greenish; Luster: Silky to pearly due to mica content; Crystal Structure: Foliated; Cleavage: Excellent in one direction (slaty/schistose); Specific Gravity: 2.5-2.9
Formation & geological history
Formed through high-grade regional metamorphism of clay-rich sedimentary rocks (shale or mudstone) or certain igneous rocks under intense heat and pressure. It is typically found in mountain belts and Precambrian shields.
Uses & applications
Used in the construction industry as flagging, decorative stone for garden walls, and occasionally as a source for quartz or mica. It is popular in landscape architecture for its shimmering qualities.
Geological facts
Schist is defined by its 'schistosity,' which refers to the alignment of mineral grains that allow it to be split into thin flakes or slabs. Many schists are older than 500 million years.
Field identification & locations
Identify in the field by its distinct layered appearance (foliation) and shiny, platy mineral flakes that sparkle in sunlight. It is commonly found in metamorphic terrains like the Appalachians or the Alps.
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