Marble is a metamorphic rock. This means that it was formed out of another rock after eons of heat and pressure. Marble is formed out of pure limestone.
Marble can be made from dynamic metamorphism, which happens with the movement of the Earth. It can also form from heat and pressure affecting large areas that may be the size of mountain ranges or from the effect of magma on the surrounding limestone.
Besides calcite, marble can have accessory minerals, such as graphite and pyrite. It can contain accidental minerals, such as quartz, mica, chlorite, diopside, plagioclase and talc. Marble can come in a wide variety of colors and be full of veins and clouds, with a grain that ranges from fine to very coarse.
Marble is prized as a building stone, but it is so soft that it can be damaged by acid rain. However, its softness makes it an excellent statuary stone. Marble has been used to construct such buildings as the Parthenon in Greece and the Taj Mahal in India. Sculptors such as Michelangelo have long sought the white marble of Carrara in Liguria, Italy.
The stone is also used for flooring and as inserts for kitchen countertops. Its coolness makes it ideal as a preparation surface for pastry making.