Calcium Carbonate

​Omya controls raw material resources for marble, chalk, limestone and dolomite in order to make calcium carbonate fillers and coating pigments for use in numerous market sectors.

Calcium carbonate is an exceptional compound. The chemical formula CaCO3 represents a raw material that exists everywhere in nature – whether dissolved in rivers and oceans, melted as "cold" carbonatite lava and solidified as a mineral, dripstone or as a parent material for whole mountain ranges.

Plants and animals need calcium carbonate to form their skeletons and shells, and even modern mankind could hardly imagine life without calcium carbonate. Almost every product in our day-to-day life contains calcium carbonate or comes into contact with it while being produced.

What is calcium carbonate?

Calcium carbonate accounts for more than 4% of the earth's crust. As a result, the three calcium carbonate minerals – calcite, aragonite and vaterite – are among the most important rock-forming minerals. Rocks are not the only calcium carbonate deposits in nature – almost all stretches of water and countless plants and animals contain huge amounts of calcium carbonate as well. These natural resources are linked by the calcium carbonate cycle.

Plants and animals absorb calcium carbonate in water, where it usually exists dissolved in the form of calcium hydrogen carbonate Ca(HCO3)2, and use it to build up their skeletons and shells. After their death, mussels, coccoliths, algae and corals form sedimentary deposits on sea beds and the rock-forming process is set in motion.

The first stage is the sedimentation process, from which chalk and limestone originate. Chalk is a poorly compacted sedimentary calcium carbonate rock whose diagenesis is incomplete.

A completed sedimentation process results in the formation of limestone. If the sedimentation process takes place in water containing magnesium, dolomitization may occur. Part of the calcium ions in the crystal lattice are replaced by magnesium ions, leading to the formation of dolomite (CaMg(CO3)2).

Marble is a metamorphic rock resulting from the recrystallization of limestone under high pressure and temperature. Whether chalk, limestone, dolomite or marble, all carbonate rocks are subject to erosion. These dissolve under the influence of wind, temperature and water, and the cycle is ready to start anew.