What do we call rock that is formed by the alteration of existing rock under heat and pressure?

Rock that is formed by the alteration of existing rock under heat and pressure is known as metamorphic rock. This process, called metamorphism, occurs when pre-existing rocks (which can be igneous, sedimentary, or even other metamorphic rocks) undergo significant changes due to increased temperature, pressure, or chemically active fluids.

During metamorphism, the mineral composition and texture of the original rock can change, leading to the formation of new minerals that were not present in the original rock. Common examples of metamorphic rocks include schist, gneiss, and marble. This unique formation process distinguishes metamorphic rock from the other types listed in the choices.

Sedimentary rock forms from the accumulation of particles and organic material, igneous rock originates from the solidification of molten magma or lava, and magma is the hot, molten rock found beneath the Earth’s surface. These processes do not involve the transformation of existing rock under heat and pressure, which is the defining characteristic of metamorphic rock.