Metamorphic Rocks – formation, characteristics and examples

Metamorphic Rock Definition

Metamorphic Rock can be defined as a type of rock that is formed by the marked transformation of other rocks such as igneous rocks and sedimentary rocks owing to heat, pressure, movement within the earth’s crust, and the chemical actions of liquids and gases.


Classification of Metamorphic rocks

Metamorphic rocks can be broadly classified into foliated metamorphic rocks and non-foliated metamorphic rocks.

The foliated metamorphic rocks have aligned mineral crystals while the non-foliated rocks do not.


metamorphic rocks definition and characteristics

How is Metamorphic Rock formed?

Metamorphic rocks are formed from other rocks under great heat and pressure and are made of different minerals more than any other rock.

The minerals are tightly bound together since they grow together in the rocks.

The exposition of igneous or sedimentary rock to different or drastic circumstances may alter the natural origin of the rock type and then be changed or transformed into metamorphic rocks, this is how igneous or sedimentary rocks become metamorphic rock.

Therefore, metamorphic rocks were once igneous rocks or sedimentary rocks most times.


Characteristics of Metamorphic rocks

The process of formation of metamorphic rocks are unique and are their classic characteristics.

Metamorphic rocks for example are not made from molten magma and do not melt but the minerals therein do change chemically.

It has layers like sedimentary rocks, and its layers can be split apart, unlike sedimentary rocks.

Metamorphic rocks are also characterized by different colors and textures.


Types of Metamorphic Rocks

There are different types and examples of metamorphic rocks and most of them have economic values and are used in construction works, home decor, cosmetics, and others.

Examples of metamorphic rocks are quartzite, slate, marble, gneiss, schist, talc, garnets.


  • Quartzite

It is a rock formed from the metamorphism of sandstone. During the process, the quartz gram is recrystallized, that is, a fusion between the cementing agents.


  • Slate

Slate is formed from the metamorphism of shale as a result of intense pressure citing on it. It consists of fine white mica.

Slate is used to producing building materials for construction works.


  • Marble

Marble is a form of metamorphic rock that results from the metamorphism of limestone and it is the most beautiful of all rocks and highly prized for its inexhaustible variety.

It ranges from the odor of snow-white to variegated ornamental types as well as uniformly colored types.

Marble is often used in home decoration, and construction works, and it’s known for its hardness.


  • Gneiss

Gneiss is formed from the metamorphism of granite which is a type of igneous rock or the transformation of conglomerates.

It is coarse-grained, and the metamorphic rock contains variations of minerals.


  • Schist

Schist is derived from the metamorphism of basic igneous rocks, for example, basalt.