Limestones are sedimentary rocks containing minerals in amounts above 30% calcium carbonate (aragonite or calcite). When the predominant mineral is dolomite limestone, is called limestone.
The limestones, mostly, are formed by the accumulation of lower organisms or precipitation of calcium carbonate in the form of bicarbonates, especially in the marine environment. Can also be found in rivers, lakes and underground (caves).
In the case of limestone quimiogénico, its origin is in the marine environment: a calcite (CaCO3) is a mineral that can form from chemical sediments, mainly calcium and bicarbonate ions.
This happens when there is loss of carbon dioxide in the marine environment, (due to strong wave, the temperature increase or pressure decrease). Additionally, to restore the carbon dioxide levels have been lost, the chemical equation begins to evolve in the direction to form CO2, with also leads to the formation of calcite and precipitation of if, later, this after a process of deposition and diagenesis, resulting in the limestone.