Most limestone was formed in shallow marine environments, such as continental shelves or platforms, though smaller amounts were formed in many other environments.
Magnesian limestone is an obsolete and poorly-defined term used variously for dolomite, for limestone containing significant dolomite ( dolomitic limestone), or for any other limestone containing a significant percentage of magnesium. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, CaMg(CO 3) 2. Ībout 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone forms when these minerals precipitate out of water containing dissolved calcium. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of CaCO 3. Limestone ( calcium carbonate CaCO 3) is a type of carbonate sedimentary rock which is the main source of the material lime. Limestone outcrop in the Torcal de Antequera nature reserve of Málaga, SpainĬalcium carbonate: inorganic crystalline calcite or organic calcareous material
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