When rocks experience greater heat and pressure, they undergo a process called metamorphism. Metamorphism changes the mineralogical composition, texture, and structure of rocks without melting them. This results in the formation of different types of metamorphic rocks, depending on the original rock composition and the conditions of metamorphism.

Some common types of metamorphic rocks include:

- Slate

Slate is a fine-grained metamorphic rock that forms from the metamorphism of mudstone, shale, or volcanic ash. It is characterized by its foliated texture, where minerals are arranged in parallel layers.

- Phyllite

Phyllite is also a fine-grained metamorphic rock, but it has a higher degree of metamorphism than slate. It is characterized by its shiny, silky texture and increased crystal size.

- Schist

Schist is a coarse-grained metamorphic rock that forms from the metamorphism of shale, mudstone, or igneous rocks. It is characterized by its foliated texture and the presence of platy minerals, such as mica or chlorite.

- Gneiss

Gneiss is a high-grade metamorphic rock that forms from the metamorphism of igneous or sedimentary rocks. It is characterized by its banded texture, where light-colored minerals alternate with dark-colored minerals.

- Marble

Marble is a metamorphic rock that forms from the metamorphism of limestone or dolomite. It is characterized by its white or light-colored appearance and its crystalline texture.

So, in summary, when rocks experience greater heat and pressure, they turn into metamorphic rocks if they do not melt. The type of metamorphic rock that forms depends on the original rock composition and the conditions of metamorphism.