Calcium Carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which is a type of sedimentary rock consisting mainly of calcite) and is the main component of eggshells, snail shells, seashells and pearls. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues

Calcium carbonate (CaCO3) is one of the most popular mineral fillers used in the plastics industry. ... As an additive in plastic compounds, CaCO3 helps decrease surface energy and provides opacity and surface gloss, which improves surface finish.