sedimentary

Shale

Laminated Fissile Pelite

Hardness: 2-3 (Mohs scale); Color: Dark gray to black (indicates organic content); Luster: Dull/Earthy; Crystal Structure: Microcrystalline clay minerals; Cleavage: High fissility (splits into thin layers).

Hardness: 2-3 (Mohs scale)
Color: Dark gray to black (indicates organic content)
Luster: Dull/Earthy

Identified July 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the compaction and lithification of silt and clay-sized mineral particles, typically in low-energy environments like lake bottoms or deep ocean basins. Ages vary from Cambrian to recent.

Uses & applications

Primarily used as a source of oil and natural gas (oil shale), as a component in cement manufacturing, and in the production of brick and pottery.

Geological facts

Shale is the most common sedimentary rock on Earth, making up over 50% of the Earth's sedimentary crust. It is the primary rock type for preserving soft-bodied fossils and organic matter.

Field identification & locations

Identify by its fine grain and ability to split easily into thin, flat sheets (fissility). It will generally not fizz with HCl unless it has high calcite content. Common worldwide in sedimentary basins.