Calcium carbonate latter is especially evident in day-to-day life of people who have hard water. Water in aquifers underground can be exposed to levels of CO much higher than atmospheric. As such water percolates through calcium carbonate rock, the CaCO dissolves according to the second trend. When that same water then emerges from the tap, in time it comes into equilibrium with CO levels in the air by outgassing its excess CO. The calcium carbonate becomes less soluble as a result and the excess precipitates as lime scale. This same process is responsible for the formation of stalactites and stalagmites in limestone
Calcium cycle layers of shell which over time cement to form limestone. This is the origin of both marine and terrestrial limestone, formed over long periods of time . The concentration of marine calcium depends on the depth of the ocean, as its solubility is altered with pressure. In deep ocean, roughly 1% more calcium is present when compared to surface concentrations. This is due to the solubility of calcium at higher pressure, thus associating higher concentration with increasing depth. The higher pressure stops calcium carbonate precipitation, whilst simultaneously enabling the dissolution of calcium carbonate sediment such as shells. As a result,