sedimentary

Shale

Laminated Mudstone (Shale)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Gray, black, or brown; Luster: Dull/Earthy; Crystal structure: Non-crystalline (fine-grained clastic); Cleavage: Fissile (splits into thin sheets); Specific gravity: 2.4 - 2.8

Hardness: 3 on Mohs scale
Color: Gray, black, or brown
Luster: Dull/Earthy

Identified July 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the compaction of silt and clay-sized mineral particles (mud) over millions of years, typically in low-energy environments like lake bottoms, river deltas, or floodplains.

Uses & applications

Used in the production of cement, brick, tile, and as a source rock for oil and natural gas (fracking). Often acts as a filler in various industrial applications.

Geological facts

Shale is the most common sedimentary rock on Earth, making up about 70 percent of the sedimentary rock in the Earth's crust. It is the primary rock type in which fossils are preserved.

Field identification & locations

Identify in the field by its tendency to split along thin, parallel planes (fissility). It feels smooth to the touch unlike sandstone and often smells earthy when wet. Common in riverbeds and road cuts.