metamorphic
Schist
Mica Schist
Hardness: 3.5–4.0; Color: Silvery-gray, brownish-gold, or greenish; Luster: Pearly to sub-metallic; Crystal Structure: Foliated; Cleavage: Perfect basal cleavage in individual mica grains; Specific Gravity: 2.7–3.0.
- Hardness
- 3
- Color
- Silvery-gray, brownish-gold, or greenish
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness: 3.5–4.0; Color: Silvery-gray, brownish-gold, or greenish; Luster: Pearly to sub-metallic; Crystal Structure: Foliated; Cleavage: Perfect basal cleavage in individual mica grains; Specific Gravity: 2.7–3.0.
Formation & geological history
Formed from the regional metamorphism of clay-rich sedimentary rocks (like shale or mudstone) under intermediate to high pressure and temperature. Primarily found in mountain ranges and ancient continental shields.
Uses & applications
Used historically as a building stone, decorative stone for gardens, flagstones, and occasionally for high-silica industrial applications. Low durability prevents heavy structural use.
Geological facts
Schist is characterized by 'schistosity,' which is the alignment of platy minerals that allows the rock to be split into thin flakes or plates. It is a step above phyllite and a step below gneiss in metamorphic grade.
Field identification & locations
Identify in the field by its distinct layered (foliated) appearance and the presence of visible, shimmering mica flakes. It often feels slightly rough or flaky when handled.
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