METAMORPHIC ROCK
Definition
<METAMORPHIC ROCK> is <ROCK> that is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means that it changed in form. That protolith was subjected to heat and pressure (temperatures greater than 150 to 200 °C and pressures of 1500 bar) causing profound physical and/or chemical change