metamorphic
Mica Schist
Mica Schist (Complex Silicate Rock)
Hardness: 3.5-5 (Mohs scale), Color: Silvery-gray to golden-brown, Luster: Pearly to metallic, Crystal structure: Platy/Foliated, Cleavage: Highly basal in individual mica crystals, Specific gravity: 2.7-3.2
- Hardness
- 3
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Physical properties
Hardness: 3.5-5 (Mohs scale), Color: Silvery-gray to golden-brown, Luster: Pearly to metallic, Crystal structure: Platy/Foliated, Cleavage: Highly basal in individual mica crystals, Specific gravity: 2.7-3.2
Formation & geological history
Formed through the regional metamorphism of pelitic rocks (shales or mudstones) under medium grade pressure and temperature. This process aligns mineral grains into parallel layers, a texture known as schistosity.
Uses & applications
Used historically as a building stone and for decorative garden landscaping. The mica minerals within are used in electronics, paints, and cosmetics for their glittery effect.
Geological facts
The 'gold' appearance in this specific specimen is likely caused by the reflection of light off weathered biotite or muscovite mica plates, a phenomenon that often leads people to mistake it for high-value gold ore.
Field identification & locations
Identify in the field by its distinct 'shimmery' or 'glittery' appearance and its tendency to flake off into small, thin plates when scratched. It is commonly found in mountain ranges and metamorphic terranes such as the Appalachians or the Alps.
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