Metamorphic Stone

Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means “change in form”. The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure (150 megapascals (1,500 bar)) causing profound physical or chemical change. The protolith may be a sedimentary, an igneous, or even an existing type of metamorphic rock.