Salt is added to food during preparation, and other mineral products may also be included. Calcium carbonate, for example, is used in bread, cakes, soups and cereal, and some food additives are manufactured using natural minerals. Sand is used to filter water, as is diatomite, a silica mineral formed from fossilised algae. Diatomite and bentonite clay are both used to clarify drinks, such as beer, fruit juices and wine.