Carbonate Definition and Examples

Seven Sisters Cliffs in Sussex
Seven Sisters Cliffs in East Sussex consist of chalk, which is calcium carbonate.

 Tim Grist Photography / Getty Images

In chemistry, a carbonate is an ion consisting of one carbon and three oxygen atoms or a compound that contains this species as its anion. The molecular formula for the carbonate ion is CO32-.

Alternatively, the term may be used as a verb referring to the process of carbonation. In carbonation, the concentration of bicarbonate and carbonate ions in an aqueous solution is increased to yield carbonated water. Carbonation is performed by introducing pressurized carbon dioxide gas or by dissolving carbonate or bicarbonate salts.

In geology, carbonates include carbonate rock and minerals, which contain the carbonate ion. The most common is calcium carbonate, CaCO3, which is found in limestone and dolomite.


  • Chisholm, Hugh, ed. (1911). "Carbonates." Encyclopædia Britannica (11th ed.). Cambridge University Press.
  • International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8.
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Helmenstine, Anne Marie, Ph.D. "Carbonate Definition and Examples." ThoughtCo, Aug. 29, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 29). Carbonate Definition and Examples. Retrieved from Helmenstine, Anne Marie, Ph.D. "Carbonate Definition and Examples." ThoughtCo. (accessed June 11, 2023).