sedimentary
Shale
Sedimentary rock composed of clay minerals and quartz
Hardness: 3 on Mohs scale; Color: Black/dark grey; Luster: Dull/earthy; Structure: Clastic, fine-grained, fissile (splits into thin layers)
- Hardness
- 3 on Mohs scale
- Color
- Black/dark grey
- Luster
- Dull/earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Black/dark grey; Luster: Dull/earthy; Structure: Clastic, fine-grained, fissile (splits into thin layers)
Formation & geological history
Formed through the compaction and lithification of silt and clay-sized mineral particles, often in low-energy environments like lake bottoms or deep ocean basins.
Uses & applications
Used as a raw material for brick, tile, and pottery; some varieties are sources of oil and natural gas (shale gas).
Geological facts
Shale is the most common sedimentary rock on Earth. It often contains fossils of microorganisms and plants due to the gentle deposition process.
Field identification & locations
Identify by its thin, flat layers (fissility) and soft texture that can often be scratched with a fingernail or penny. Found globally in basins and river deltas.
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