Marble

Marble is a metamorphic stone. It is formed when limestone is subjected to both heat and pressure and is primarily composed of calcite (CaCO3). Typically, clay minerals, micas, quartz, pyrite, iron oxides, and graphite are also present. Given metamorphic conditions, the calcite in the limestone recrystallizes to form a rock that is a mass of interlocking calcite crystals, which is marble.