Bentonite clay comes from volcanic ash, it is a colloidal clay, consisting primarily of montmorillonite (CI 77004). Bentonite is a general term for a group of highly absorbent, mineral rich clays. Bentonite clays are usually classified based on their main component: sodium, calcium, or potassium.
Bentonite is used in masks, lotions (to thicken them) and foundations (to suspend makeup pigments). It’s also used in soaps. Pure bentonite pH is usually around an 8-9 (before it’s mixed with water and other ingredients).
When bentonite clay is mixed with water, it swells and is highly porous and able to absorb oils and “impurities”. It’s attracting action is from an “electrical” charge (obviously molecular, not painful in any way) and the impurities stay in the clay, not in or on your skin.