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Shale
Fine-grained, clastic sedimentary rock / From Wikipedia, the free encyclopedia
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2Si2O5(OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.[1] Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness. This property is called fissility.[1] Shale is the most common sedimentary rock.[2]
For other uses, see Shale (disambiguation).
The term shale is sometimes applied more broadly, as essentially a synonym for mudrock, rather than in the narrower sense of clay-rich fissile mudrock.[3]