Everyone is familiar with the word limestone; the chemical name of limestone is calcium carbonate. CaCO3 is one of the most abundant compounds found naturally. It is present in excess in nature like eggshells, snail shells, seashells, and even pearls; calcium carbonate is present. It is present in the earth’s crust as chalk, limestone, marble, etc. Calcium carbonate has many forms which are chemically different from each other; but physically are the same like, calcite and aragonite. It is widely available and an inorganic compound with the chemical formula CaCO3.