metamorphic
Schist
Mica Schist
Hardness: 3.5-4; Color: Silver, grey, or black with golden tints; Luster: Pearly to vitrous; Crystal structure: Foliated with prominent mica flakes; Cleavage: One perfect direction (basal); Specific gravity: 2.7-2.8
- Hardness
- 3
- Color
- Silver, grey, or black with golden tints
- Luster
- Pearly to vitrous
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Physical properties
Hardness: 3.5-4; Color: Silver, grey, or black with golden tints; Luster: Pearly to vitrous; Crystal structure: Foliated with prominent mica flakes; Cleavage: One perfect direction (basal); Specific gravity: 2.7-2.8
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under high pressure and temperature conditions. It typically occurs in mountain belts and Precambrian terrains.
Uses & applications
Used primarily in construction for decorative stones, flagstones, and garden paths. Fine-grained varieties are sometimes used for slate-like purposes, and mineral-rich slabs are sought by collectors.
Geological facts
The word 'schist' is derived from the Greek word 'schizein' meaning 'to split', referring to how easily the rock can be peeled into thin layers. It is distinguished from gneiss by its higher mica content and finer foliation.
Field identification & locations
Identify in the field by its distinct 'schistosity' or flaky, layered appearance that glitters in sunlight due to mica. Found globally in ancient tectonic plate boundaries and eroded mountain ranges.
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