Fine-grained clastic sedimentary rock formed from compacted clay and silt. The most common sedimentary rock, showing fissility. Texture: Fine-grained, fissile. Rock type: Sedimentary Clastic. Grain size: Clay to silt <0.0625 mm. Parent rock: Clay/silt deposits. Minerals present: Clay minerals, Quartz, Feldspar, Mica. Formation: Forms from compaction of clay-rich sediments in low-energy environments like deep ocean floors, lakes, and floodplains. Common geological settings: Worldwide; forms thick sequences in sedimentary basins. Significant shale gas reserves. Common look-alikes and related entries: Mudstone, Siltstone, Slate.
Shale vs Slate — Compare observable properties and safer field tests.
Siltstone vs Shale — Compare observable properties and safer field tests.
Shale vs Mudstone — Compare observable properties and safer field tests.
Sources, scope & corrections
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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GeoMiner
Last updated
2026-03-30T14:37:23.348302+00:00
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Published; not independently peer-reviewed
Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
Fine-grained clastic sedimentary rock formed from compacted clay and silt. The most common sedimentary rock, showing fissility.
How can you identify Shale?
Compare several properties rather than relying on colour alone. This entry records rock type: Sedimentary Clastic; texture: Fine-grained, fissile; grain size: Clay to silt <0.0625 mm; common minerals: Clay minerals, Quartz, Feldspar, Mica. Confirm an important identification with additional field tests or qualified laboratory work.
How does Shale form?
Forms from compaction of clay-rich sediments in low-energy environments like deep ocean floors, lakes, and floodplains.
Where is Shale commonly found?
Worldwide; forms thick sequences in sedimentary basins. Significant shale gas reserves.
What is Shale commonly confused with?
Shale may be confused with Mudstone, Siltstone, Slate. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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