What is Calcium Carbonate?

Calcium Carbonate is an exceptional mineral. The chemical formula CaCO3 covers a raw material, which is widespread throughout nature, whether dissolved in rivers and oceans, in molten form as “cold” carbonatite-lava, or solid as a mineral in the form of stalactites, stalagmites or as the major constituent of whole mountain ranges. Plants and animals need calcium carbonate to form their skeletons and shells. In fact, when considering our lives, modern mankind could hardly imagine existing without calcium carbonate. Almost every product in our daily lives either contains calcium carbonate or has some association with the mineral during its production.

Origin

The Earth’s crust contains more than 4% calcium carbonate. 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, most stretches of water and countless plants and animals contain huge amounts of calcium carbonate.

The calcium carbonate cycle

The link between these natural resources is the calcium carbonate cycle. Plants and animals absorb calcium carbonate from water - where it exists, in most cases, in the dissolved form of calcium hydrogen carbonate Ca(HCO3)2 - and use it to build up their skeletons and shells. After their death, crustacea, coccoliths, algae and corals form sedimentary deposits on sea-beds, thus the rock forming process, is put 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. When the sedimentation process is completed this results in the formation of limestone. If the sedimentation process takes place in magnesium containing water a dolomitisation may occur. Part of the calcium ions in the crystal lattice are replaced by magnesium ions, a fact that leads to the formation of dolomite CaMg[CO3]2. Marble is a metamorphic rock, which is the result of a re-crystallisation process of limestone, under conditions of high pressure and temperature. The carbonate rocks, chalk, limestone, dolomite and marble rocks are subject to erosion; under the influence of wind, temperature and water they dissolve, and the cycle may start again.

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