Marble is a recrystallized limestone that formed when the limestone softened from heat and pressure and recrystallized into marble where mineral change occurred. The main consistency is calcium and dolomite. Ranges in many colors and is usually heavily veined and shows lots of grains. It has been very popular for sculpture and building construction because of its beauty and relative softness. It is vulnerable to weathering since its calcium carbonate content is readily attacked by acid rain.