sedimentary or metamorphic

Shale or Slate

Shale (Sedimentary) or Slate (Metamorphic)

AI-generated identification · may be incorrect

Fine-grained, dark gray to black color, smooth surface, exhibits fissility (tends to split into thin layers). Hardness varies but generally low (3-4 on Mohs scale).

Identified August 18, 2026More sedimentary or metamorphic →

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Physical properties

Fine-grained, dark gray to black color, smooth surface, exhibits fissility (tends to split into thin layers). Hardness varies but generally low (3-4 on Mohs scale).

Formation & geological history

Formed from the compaction of silt and clay-size mineral particles that we normally call mud. If subjected to low-grade metamorphism, it becomes slate.

Uses & applications

Used historically for roofing, flooring, and blackboards if it is slate. Shale is a source rock for oil and gas, and used in making brick and cement.

Geological facts

Black shales are organic-rich and often associated with anoxic environments during deposition.

Field identification & locations

Identified by its fine grain size, dark color, and tendency to break into flat sheets. Commonly found in sedimentary basins or areas of low-grade regional metamorphism.