Calcium carbonate oxide is not a compound. There are two separate compounds that can be formed from calcium, carbon and oxygen:

* Calcium carbonate, CaCO3, is a white, crystalline solid that is the main component of limestone, marble, and chalk. It is also used as an antacid and as a source of calcium in food and dietary supplements.

* Calcium oxide, CaO, is a white powder that is also known as quicklime. It is used in the production of cement, mortar, and glass, and as a flux in steelmaking.