Well-known metamorphic rocks are marble and slate. Igneous rocks are made when liquified rock, called magma or lava, cools and solidifies. Well-known igneous rocks are obsidian and granite.

The rocks on Earth are constantly changing due to many different processes. There are three main types of rock, with rocks changing between each type over millions of years.

Igneous or sedimentary rocks can be subjected to enough heat or pressure to reform them into a third kind of rock: metamorphic. (Schist or marble, for examples.) ...

Article #20-00095: "Thermogenic carbon release from the Central Atlantic magmatic province caused major end-Triassic carbon cycle perturbations," by Thea H. Heimdal, Morgan T. Jones, and Henrik. H.