metamorphic
Schist
Mica Schist
Hardness: 3.5-4; Color: Silvery-gray, greenish, or bronze; Luster: Pearly to sub-metallic (sheen); Crystal structure: Foliated (platy); Cleavage: Excellent in one direction (micaceous); Specific Gravity: 2.7-2.8
- Hardness
- 3
- Color
- Silvery-gray, greenish, or bronze
- Luster
- Pearly to sub-metallic (sheen)
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Physical properties
Hardness: 3.5-4; Color: Silvery-gray, greenish, or bronze; Luster: Pearly to sub-metallic (sheen); Crystal structure: Foliated (platy); Cleavage: Excellent in one direction (micaceous); Specific Gravity: 2.7-2.8
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under medium-grade temperatures and pressures. Most common in mountain-building zones (orogenic belts). Often dating from the Precambrian to Cenozoic eras.
Uses & applications
Used primarily as decorative stone, flagstone for walkways, heat-resistant surfaces, and occasionally in the production of talc or as a source of garnets for industrial abrasives.
Geological facts
Schist is characterized by its large, platy mineral grains called 'schistosity.' It often contains 'porphyroblasts'—large crystals like garnet or staurolite that grow within the finer matrix during metamorphism.
Field identification & locations
Identify by its 'schisty' sheen and visible layering that looks like it could peel into thin flakes. Commonly found in riverbeds near mountainous regions. Look for the characteristic sparkle when rotated in the sunlight.
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