Carrara white marble
Marble is a metamorphic, sedimentary rock composed mainly of calcium carbonate.
The colour of marble depends on the presence of mineral impurities (clay, silt, sand, iron oxides, nodules of flint), existing granules or layers within the original sedimentary rock. During the metamorphic process such impurities are shifted and re-crystallised due to pressure and heat. White marbles are a result of the metamorphosis of limestone that has no impurities.