calcium carbonate, is a chemical compound commonly found in nature. They exist in constituent substances of plenty living animals (the hard shells of marine animals such as shellfish, snails, pearls or eggshells) as well as geological forms. The most popular and well-known source of CaCO₃ is from limestone ores, a sedimentary rock often formed near waterfalls or streams. This is also the main source to provide calcium carbonate filler for plastic industry. In addition, calcium carbonate can be found in other minerals and rocks such as chalk, marble, limestone, otufa and travertine.