Marble is a metamorphic rock form composed of coarse crystals from parent limestone or dolostone rocks. Pure marble is white and composed of the mineral calcite. 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.
Pure white marble is the result of metamorphism of very pure limestones. The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from originally high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism
Metamorphic rocks are those which have been changed from one form to another by the high pressure and temperature environment of the Earth. "Metamorphism" means the process of changing form.
Dolostone or dolomite rock is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite.
Dolomite is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate.