Knowra Calcium carbonate Calcium carbonate Calcium carbonate (CaCO₃) is an inorganic compound that occurs in minerals including calcite and aragonite and forms much of limestone, chalk, and shells.
Calcite : A crystalline mineral form of calcium carbonate with a trigonal crystal structure. It is the most widespread crystalline form of calcium carbonate in rocks.
Calcium carbonate cycle : The natural transfer of calcium carbonate among dissolved ions, organisms, sediments, and rocks. It connects carbonate precipitation, biological shells, and geological deposits.
Limestone : A sedimentary rock composed chiefly of calcium carbonate, commonly derived from accumulated biological material. Limestone is the principal geological feedstock for many calcium carbonate products.
Biomineralization : The process by which living organisms produce minerals as part of biological structures. Many organisms build calcium carbonate structures through controlled mineral formation.
Dolomite : A carbonate mineral, CaMg(CO₃)₂, containing calcium and magnesium. Unlike calcium carbonate, dolomite’s formula includes magnesium as well as calcium.
Aragonite : An orthorhombic crystalline form of calcium carbonate, less stable at Earth’s surface than calcite. It is calcium carbonate’s other major natural crystal form.
Carbonate–silicate cycle : A long-term geological cycle that regulates atmospheric carbon dioxide through weathering, burial, and volcanism. Calcium carbonate burial stores carbon removed from the atmosphere by weathering.
Chalk : A soft, porous limestone composed mainly of microscopic marine calcite remains. Its fine-grained calcium carbonate has distinctive geological and commercial uses.
Mollusk shell : A hard external structure secreted by a mollusk, commonly composed largely of calcium carbonate. Mollusks deposit calcite or aragonite to build their shells.
Gypsum : A soft sulfate mineral composed of hydrated calcium sulfate, CaSO₄·2H₂O. It is another common calcium mineral, but contains sulfate rather than carbonate.
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