Shale is one of the important type of rocks. If we have to define Shale in general, Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles. Shale comes under Sedimentary Rocks. All Sedimentary Rocks have similar properties and formation process. Along with Shale Definition, know more about the History of Shale, Etymology of Shale in next sections.