Shale refers to a rock with thin leaf-like or flake-like bedding formed from weakly consolidated clay and formed by strong pressure, dehydration, and recrystallization. The composition of shale is complex. In addition to clay minerals (such as kaolinite, montmorillonite, hydromica, baylite, etc.), it also contains many quartz, feldspar, mica, and oxides and hydroxides of iron, aluminum, and manganese. wait. Different shale has different chemical compositions. The content of different chemical compositions of shale that exists in nature also varies greatly. Common shale includes: black shale, carbonaceous shale, oil shale, siliceous shale, ferrous shale, and calcareous shale. In addition, shale mixed with certain sandy components is called sandy shale.