Shale

Compacted mud and clay that splits into thin layers. The most common sedimentary rock.

Shale specimen — Photo: James St. John, CC BY 2.0, via Wikimedia Commons

How to identify shale

Splits into thin, flat flakes along its layers.
Grains too small to see.
Smells earthy when wet.
Soft and crumbly at edges.

Often confused with

Slate
Slate is harder and rings when tapped; shale gives a dull thud.
Compare side by side

Where it's found

Burgess Shale, British Columbia
Marcellus, Pennsylvania
Bakken, North Dakota

Uses

Brick, cement and a source rock for oil and gas.

Rock tumbling

Not suitable for tumbling.

Did you know?

The Burgess Shale preserves soft-bodied animals from over 500 million years ago.

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