Metamorphism from its prefix "meta" means the structural change of rocks by natural agents such as pressure, heat or introduction of chemical substances. For this event to occur, temperatures and pressures must be higher than 200-degrees C and 300 MPa (megapascals). Temperature is the key variable for metamorphism to occur because heat is required for chemical reactions to take place, thus, as temperature increases, the rate to which the ions diffuse between minerals also increases, albeit it should be noted that it is a slow process since the ions have to permeate through a solid rock. The process is hastened through water, which allows a faster diffusion of ions.
