CalciumcarbonatVerbindungen

Calcium carbonate is a chemical compound with the formula CaCO3. It occurs widely in nature as the minerals calcite and aragonite, which have different crystal structures. It is a major component of rocks such as limestone, marble, and chalk, and it also forms seashells, coral skeletons, and some cave formations.

In nature, calcium carbonate exists in several crystalline forms. Calcite is the most stable and common form at Earth's surface, while aragonite is found in many marine organisms and can transform to calcite over time. Vaterite is a less common polymorph. Calcium carbonate contributes to the buffering capacity of natural waters and plays a key role in the carbon cycle.

Industrial and practical uses are diverse. It is used as a building material in the form of limestone and marble, as well as in cement and lime production. It serves as a filler and whitening agent in paper, plastics, and paints, and as a calcium supplement in food and medicine. In agriculture, finely ground calcium carbonate is used to neutralize acidic soils. It also finds application in environmental remediation, wastewater treatment, and as aponent in various chemical processes.

Chemically, calcium carbonate is insoluble in water but reacts with acids to release carbon dioxide. It can be thermally decomposed in air to calcium oxide (CaO) and CO2, and the oxide can be hydrated to form calcium hydroxide (Ca(OH)2). The mineralogical and industrial versatility of CaCO3 underpins its extensive use worldwide.