Marble is stone resulting from the metamorphism of sedimentary carbonate rocks–most commonly limestone or dolomite rock. The characteristic swirls and veins of marble result from the presence of various mineral impurities such as clay, silt, sand, iron oxides and silica when the stone formed. It is softer and more porous than granite. Care is required to prevent scratching, etching, and staining. Marble is also quarried. Colour and pattern variations will exist.