The Carrara marble, as all the marble, a metamorphic rock is formed by crystals of calcium carbonate of almost microscopic dimensions. It is originated from pre-existing rocks that as a result of strong variations in pressure and / or temperature have undergone a complete reorganization of the crystalline structure such as to be transformed into all of the different types of rocks. In the case of the Carrara marble the original rock was a limestone similar to those that currently make up the largest coral reefs of tropical seas. Its formation dates back to the Lower Jurassic (190 million years ago), when most of the regions now corresponding to northern Tuscany were covered by a vast sea was deposited on the bottom of a limestone sediment that gave rise to a carbonate platform.