Calcium Cycle

The calcium cycle is the biogeochemical cycle describing the continual transfer of calcium between dissolved and solid forms as it moves through rock, water, and living organisms. Calcium is stored mainly in geological deposits as calcium carbonate and calcium silicate minerals, including calcite, dolomite, and gypsum, and it also exists dissolved as calcium ions in the ocean. Weathering of rock releases calcium into rivers and eventually the sea, where marine organisms such as coccolithophores, corals, pteropods, and mollusks draw dissolved calcium and bicarbonate out of the water to build shells and skeletons of calcium carbonate, the dominant sink for dissolved ocean calcium; when these organisms die, their remains accumulate on the seafloor and can eventually form limestone, while living organisms also rely on calcium for bones, teeth, cell signaling, blood clotting, and muscle contraction. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/