metamorphic
Slate
Metamorphic Pelitic Rock
Hardness: 3-4 on the Mohs scale, Color: Grey, black, green, or red, Luster: Dull to sub-mat, Crystal Structure: Microcrystalline, Cleavage: Excellent slaty cleavage, Specific Gravity: 2.6-2.8
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Physical properties
Hardness: 3-4 on the Mohs scale, Color: Grey, black, green, or red, Luster: Dull to sub-mat, Crystal Structure: Microcrystalline, Cleavage: Excellent slaty cleavage, Specific Gravity: 2.6-2.8
Formation & geological history
Formed by low-grade regional metamorphism of mudstone or shale, typically originating in tectonic compression environments over millions of years.
Uses & applications
Used in roofing, flooring, billiards tables, blackboards, and decorative aggregate.
Geological facts
Slate's exceptional ability to split into thin, durable sheets has made it a preferred construction and writing material for centuries.
Field identification & locations
Identify by its distinctive parallel foliation (slaty cleavage) and fine-grained texture. Commonly found in mountainous regions and areas with ancient tectonic activity.
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