Rocks that have been altered by heat and pressure are called what?

Rocks that have been altered by heat and pressure are classified as metamorphic rocks. This classification stems from the processes they undergo, which involve significant temperature and pressure changes that can occur deep within the Earth's crust. During metamorphism, pre-existing rocks (either igneous, sedimentary, or even other metamorphic rocks) are transformed. These transformations can result in changes to the mineral composition, texture, and structure of the rock, ultimately yielding a completely new type of rock.

For instance, limestone, when subjected to heat and pressure, can undergo metamorphism to become marble. This process illustrates how metamorphic rocks take on new characteristics that distinguish them from igneous and sedimentary rocks, which are formed through different geological processes: igneous rocks crystallize from molten rock, while sedimentary rocks are formed from the accumulation of mineral and organic particles. Basaltic refers specifically to a type of igneous rock, characterized by its composition and texture, further solidifying that the correct response relates to the metamorphic class of rocks.