sedimentary

Shale

Shale (Lutite)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Gray to dark black; Luster: Dull; Crystal structure: Non-crystalline (clastic); Cleavage: Fissile (splits into thin layers); Specific gravity: 2.4 - 2.8

Hardness: 3 on Mohs scale
Color: Gray to dark black
Luster: Dull

Identified July 9, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Gray to dark black; Luster: Dull; Crystal structure: Non-crystalline (clastic); Cleavage: Fissile (splits into thin layers); Specific gravity: 2.4 - 2.8

Formation & geological history

Formed through the compaction of silt and clay-sized mineral particles over millions of years, typically in low-energy environments like lake beds or deep ocean floors.

Uses & applications

Used in the production of bricks, tile, and cement. Dark shales are also major sources of natural gas and petroleum via fracking.

Geological facts

Shale is the most common sedimentary rock on Earth. Deeply buried shale is often the source rock for many of the world's hydrocarbon deposits.

Field identification & locations

Identify in the field by its distinct layering and 'fissility', meaning it breaks easily along flat planes. Common in river basins and ancient sea beds.