sedimentary
Shale
Argillite / Shaly Mudstone
AI-generated identification · may be incorrectHardness: 3 on Mohs scale; Color: Gray to brownish; Luster: Dull/Earthy; Structure: Fissile, layered; Cleavage: Perfect along bedding planes.
- Hardness
- 3 on Mohs scale
- Color
- Gray to brownish
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Gray to brownish; Luster: Dull/Earthy; Structure: Fissile, layered; Cleavage: Perfect along bedding planes.
Formation & geological history
Formed from the compaction of silt and clay-size mineral particles, typically in low-energy environments like lake bottoms, floodplains, or deep ocean floors.
Uses & applications
Used as a raw material for brick, tile, and pottery; also a major source of natural gas and petroleum via hydraulic fracturing.
Geological facts
Shale is the most common sedimentary rock on Earth, making up over 50% of the sedimentary rocks in the crust. Many fossils are found preserved in shale due to the fine-grained sediment.
Field identification & locations
Identifiable by its thin, flat layers that break easily (fissility). Look for it in road cuts, riverbeds, and sedimentary basins worldwide.
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Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary