Marble is a metamorphic rock that begins its life as limestone or dolostone, a sedimentary rock primarily composed of the mineral calcite (calcium carbonate).
This precursor rock forms at the bottom of seas or lakes over millions of years from the immense pressure of accumulated shell, coral, algal, and other organic debris.
The transformation into marble occurs through a process called metamorphism. When tectonic forces push sections of the Earth's crust together, this limestone gets buried deep underground, subjected to intense heat and tremendous pressure.
This "bakes" the rock, causing the calcite crystals to recrystallize and interlock. This process destroys the original fossils and sedimentary layers, creating a new, denser, and harder rock with a characteristic sugary or sparkling appearance-marble.
Famous sources of marble include Carrara in Italy (source of Michelangelo's stone), Vermont in the USA, and quarries in Greece, Turkey, and Spain.
