metamorphic
Slate
Slate (Metamorphic Rock)
Hardness: 2.5-4 on Mohs scale. Color: Dark gray to black. Luster: Dull to slightly satiny. Cleavage: Perfect slaty cleavage, splitting into thin, flat sheets. Grain size: Very fine-grained.
- Hardness
- 2
- Color
- Dark gray to black
- Luster
- Dull to slightly satiny
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Physical properties
Hardness: 2.5-4 on Mohs scale. Color: Dark gray to black. Luster: Dull to slightly satiny. Cleavage: Perfect slaty cleavage, splitting into thin, flat sheets. Grain size: Very fine-grained.
Formation & geological history
Formed by low-grade regional metamorphism of shale or mudstone under intense pressure and mild heat, typically in convergent plate boundaries or mountain-building regions.
Uses & applications
Widely used for roofing tiles, flooring, pool table tops, flagstones, outdoor landscaping, and decorative stone work.
Geological facts
Slate can split into extremely thin, durable sheets due to slaty cleavage caused by the parallel alignment of microscopic mica minerals during compression.
Field identification & locations
Identified in the field by its fine grain, dark color, and characteristic planar splitting (slaty cleavage). Commonly found in slate quarry regions, stream beds near metamorphic terrains, and as gravel/landscaping stone.
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