sedimentary

Red Shale

Fissile Siliciclastic Sedimentary Rock

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Reddish-brown to maroon due to iron oxide (hematite); Luster: Dull/Earthy; Structure: Fine-grained, fissile (splits into thin layers); Cleavage: Perfect parallel to bedding planes.

Hardness: 3 on Mohs scale
Color: Reddish-brown to maroon due to iron oxide (hematite)
Luster: Dull/Earthy

Identified March 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the compaction of silt and clay-sized mineral particles over millions of years. The red color indicates formation in an oxygen-rich environment, typically in floodplains or shallow lake basins where iron was oxidized.

Uses & applications

Used in the manufacturing of bricks, terracotta tiles, and cement. In crushed form, it is used as road base or fill material. High-quality clay-rich shales are also used in ceramics.

Geological facts

Shale is the most common sedimentary rock on Earth, accounting for about 70 percent of the rocks in the Earth's crust. Red shales are often associated with fossils of land plants or tracks because they form in terrestrial or near-shore environments.

Field identification & locations

Identify in the field by its distinct layering and tendency to flake apart into flat plates. It will not fizz with acid (distinguishing it from limestone) and is soft enough to be scratched by a copper penny. Found abundantly in the Appalachian Mountains and the Southwestern United States.