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Calcium carbonate is a chemical compound, with the chemical formula CaCO3. The elements involved are calcium (Ca), carbon (C) and oxygen (O). It is a common substance found as rock in all parts of the world, and is the main component of seashells, snails, and eggshell. Calcium carbonate is usually the main cause of hard water. It is used as a calcium supplement or as a treatment for antacid, but too much can be bad for your health.
Calcium carbonate is found naturally as the following minerals and rocks:
To test whether a mineral or rock contains calcium carbonate, strong acids, such as hydrochloric acid, can be added to it. If the sample does contain calcium carbonate, it will fizz and produce carbon dioxide and water. Weak acids such as acetic acid will react, but less quickly. All of the rocks/minerals mentioned above will react with acid.