metamorphic rocks

Deep inside the Earth, intense heat and pressure can change rocks into entirely new metamorphic rocks. In fact, the conditions are so extreme, they can change the rock's texture, color, and the shape of its crystals. Even the rock’s minerals are broken down and new ones are formed. This can happen to any rock—igneous, sedimentary, even other metamorphic rocks. It's all part of the Earth's rock cycle.

Definition: rock that changes from heat and pressure
Where it forms: usually deep within the Earth's crust where it is hot and pressures are high
Common examples: marble, slate, schist
Cool fact: The mantle is made entirely of metamorphic rock.

Image credits: main image, courtesy of AMNH; Rondi Davies: courtesy of AMNH.