Aluminum hydroxide is a mineral found in nature. It's a very stable form of aluminium closely related to Alumina, not to be confused with aluminium salts (like Aluminum chloride, Aluminum nitrate, Aluminum sulphate) often used in deodorants. Aluminum hydroxide is often used to treat heartburn by neutralizing stomach acids. Toothpastes also often contain Aluminum hydroxide, where it is used as an abrasive and neutralises the effect of acids in the mouth, which can help to reduce the amount of germs. In makeup it is mostly used in primers, foundations, and lipsticks and in skin care it can often be found in moisturizers (where it is used as an emolient, opacifying agent (making a product less transparent), and skin protectant. It can also often be found in sunscreens, where it is used to coat titanium dioxide, making it much more stable while at the same time increasing the SPF. It also prevents it from clumping to it spreads easier. Aluminum hydroxide is generally seen as very safe and can be used in certified natural cosmetics.