Shale
“Earth's most common sedimentary rock”
Sedimentary
Shale is a fine-grained sedimentary rock formed from compacted mud, clay, and silt deposited in calm, low-energy environments like lake beds and deep ocean floors. It preserves fossils exceptionally well due to its fine layering.
Composition
clay minerals, quartz, feldspar, calcite, organic carbon
Where Found
Burgess Shale (Canada), Marcellus Formation (USA), North Sea Basin (Europe)
Mohs Hardness
1.5-3
Fun Fact
The Burgess Shale in Canada contains some of the world's most important fossils, preserving soft-bodied organisms from over 500 million years ago.
Test Your Knowledge
Why is shale particularly problematic as a foundation material for buildings?
Related Specimens
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