metamorphic
Slate
Slate (Low-grade metamorphism of shale/mudstone)
AI-generated identification · may be incorrectHardness: 2.5-4 Mohs; Color: Grey, charcoal, or dark green; Luster: Dull to sub-lustrous; Structure: Foliated with slaty cleavage; SG: 2.7-2.8.
- Hardness
- 2
- Color
- Grey, charcoal, or dark green
- Luster
- Dull to sub-lustrous
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Physical properties
Hardness: 2.5-4 Mohs; Color: Grey, charcoal, or dark green; Luster: Dull to sub-lustrous; Structure: Foliated with slaty cleavage; SG: 2.7-2.8.
Formation & geological history
Formed through low-grade regional metamorphism of shale or mudstone under low pressure and temperature conditions. It typically dates back to various eras where tectonic plates collided.
Uses & applications
Used widely in roofing, flooring, billiard table surfaces, and blackboards due to its ability to be split into thin, flat sheets. Also used for decorative landscaping.
Geological facts
Slate is excellent at retaining heat and is virtually waterproof, making it one of the longest-lasting roofing materials available, sometimes lasting over 100 years.
Field identification & locations
Identified by its fine-grained texture and characteristic slaty cleavage (breaking into thin, parallel planes). Commonly found in mountainous regions such as the Appalachian Mountains or Wales.
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