What is Calcium Carbonate?

a mound of white powder on a grey background

What is Calcium Carbonate Used For?

Calcium carbonate is a chemical compound composed of calcium, carbon and oxygen atoms. It's a common mineral found in rocks.

Calcium carbonate is the main ingredient of chalk, limestone, marble, eggshells, snail shells, the shells and skeletons of sea creatures and pearls.  

Calcite and aragonite are crystalline forms of calcium carbonate.

It forms in seawater when dissolved calcium ions combine with dissolved carbon dioxide. The calcium carbonate is insoluble in water and precipitates out of the solution.

This process plays an important role in the formation of many geological features, such as coral reefs and limestone. 

Calcium carbonate can also form when calcium ions found in hard water react with carbonate ions. This leads to the formation of limescale, which is mostly made up of calcite.

Hard water contains high levels of dissolved minerals, including calcium and magnesium. When heated, the minerals gradually precipitate. The deposit that forms is limescale.
 
Calcium carbonate is a useful, naturally occurring substance with many industrial and commercial uses. It's used in the production of paper, plastic, paint, and many other products that we use every day.

Here are some examples; 

Calcium carbonate is used to produce asphalt, cement, concrete and bricks. In agriculture, it's used as a conditioner to neutralise acid in soils. It's also used as a calcium supplement in animal feed.

Calcium carbonate is used as a food additive, particularly in baked goods and cereals. Not only is it a source of calcium, but it also improves texture.

It can be used as a dietary supplement and as an antacid to treat stomach acid. It's used in paper production to improve quality and brightness.

In paints, calcium carbonate improves whiteness, opacity and matting. Matting makes the paint look less glossy. 

In environmental applications, calcium carbonate is used to increase alkalinity in water.

Article Photos

All pop-up photos are courtesy of Stan Celestian. The original images are here: Limestone, marble, calcite.

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