Also known as dolomite, it is recrystallized limestone, mainly composed of CaCO ｜. Limestone becomes soft under high temperature and pressure, and recrystallizes to form marble when the mineral content changes. The main components are calcium and dolomite, with many colors, obvious patterns and many mineral grains. The Mohs hardness is between 2.5 and 5. Marble generally contains impurities, and calcium carbonate is also easy to be weathered and corroded by carbon dioxide, carbide and water vapor in the atmosphere, which makes the surface lose luster quickly.