Bentonite is a kind of clay rock, also called montmorillonite clay rock, which often contains a small amount of illite, kaolinite, halloysite, chlorite, zeolite, quartz, feldspar, calcite, etc; It is generally white and light yellow, and due to changes in iron content, it appears as light gray, light green, pink, brownish red, brick red, gray black, etc; Having a waxy, earthy, or greasy luster; Some bentonite is loose like soil, while others are dense and hard. The main chemical components are silicon dioxide, aluminum trioxide, and water, as well as elements such as iron, magnesium, calcium, sodium, potassium, etc. The content of Na2O and CaO has a significant impact on the physical and chemical properties and technological performance of bentonite. Montmorillonite mineral belongs to monoclinic crystal system, usually in the form of earthy block, white, sometimes with light red, light green, light yellow and other colors. The luster is dim. Hardness 1-2, density 2-3 g/cm3. According to the type, content and layer charge of exchangeable cation of montmorillonite, bentonite can be divided into sodium bentonite (alkaline soil), calcium bentonite (alkaline soil), natural bleaching soil (acid soil or acid clay), among which calcium bentonite also includes calcium sodium base and calcium magnesium base. Bentonite has strong hygroscopicity and expansibility, and can adsorb 8-15 times its own volume of water, with a volume expansion of several to 30 times; In aqueous media, it can disperse into gelatinous and suspended forms, and this medium solution has certain viscosity, variability, and lubricity; Has strong cation exchange ability; Has a certain adsorption capacity for various gases, liquids, and organic substances, with an adsorption capacity of up to 5 times its own weight; It has plasticity and bonding properties when mixed with water, mud or fine sand; Acid bleached soil with surface activity (activated white soil, natural bleached soil acidic white soil) can adsorb colored ions.

Bentonite has strong hygroscopicity and can adsorb water equivalent to 8-20 times its own volume, expanding to 30 times; In water medium, it can be dispersed as colloidal suspension, and has certain viscosity, thixotropy and lubricity. It has plasticity and cohesiveness with sediment and other admixtures, and has strong cation exchange capacity and adsorption capacity.