Bentonite is a non-metallic mineral with montmorillonite as the main mineral component. This kind of soil can swell into a paste after adding water. Later, people called all clays with this kind of properties collectively as bentonite. In fact, the main mineral component of bentonite is montmorillonite, with a content of 85-90%. Some properties of bentonite are also determined by montmorillonite. Montmorillonite can be in various colors such as yellow-green, yellow-white, gray, white and so on. It can be a dense block or loose soil. It has a slippery feel when rubbed with your fingers. The volume of the small block swells several times to 20-30 times after adding water. It is suspended in water, and it is mushy when there is little water. The properties of montmorillonite are related to its chemical composition and internal structure.