Human: How do you know when a rock is metamorphic? Assistant: 
Metamorphic rocks are formed when igneous rocks are subjected to high pressure and/or temperature. This causes the minerals in the rock to change their chemical composition and physical structure. Metamorphic rocks are often found in mountain ranges, where they are exposed to high temperatures and pressures. Metamorphic rocks are also found in the ocean floor, where they are exposed to high pressure and temperature.