Calcium Carbonate

chemistry · rocks · nature

Eggshell ingredient. Eggshells are made almost entirely of calcium carbonate, which is why they are hard and white. This same compound helps protect baby birds until they are ready to hatch.

Rock builder. Calcium carbonate is found in common rocks like limestone and chalk all around the world. These rocks often started as shells and skeletons of sea creatures that piled up on the ocean floor millions of years ago.

Pearl maker. Oysters and other shellfish create pearls by coating irritating particles with layers of calcium carbonate. This is the same compound that forms their protective shells.

Medicine helper. Calcium carbonate is added to some medicines called antacids that help calm an upset stomach. It is also used as a calcium supplement to keep bones strong and healthy.

Limescale problem. When hard water sits in pipes and kettles, calcium carbonate builds up as a crusty white deposit called limescale. This happens because minerals in the water react and form this compound.