Rocks (Chemistry)

Igneous Rock

Inside the Earth, there is molten rock called magma. When magma cools down, the minerals will crystalise to form Igneous Rock. When magma escapes onto the Earth`s surface i.e a volcano. The lava will cool quickly where as underground it will cool slower. The slower the liquid cools the bigger the crystals are.

Intrusive Igneous Rock- This type of Igneous rock is formed underground, therefore, it will have larger crystals. An example of this type of rock is Granite.

Extrusive Igneous Rock- This type of Igneous Rock is formed on the Earth`s surface. The crystals are much smaller than an intrusive rock. An example of this is Basalt.

Sedimentary Rock

The fragments of rocks which are formed by weathering and erosion which are carried by rivers are called sediment.

These fragments are taken by rivers until the river reaches the sea. Here the sediment settles to the bottom (deposition.) The over years sediment builds and compacts the sediment underneath. Minerals from water cement the sediment together to make a rock.

Examples of Sedimentary rock are Sandstone and Conglomerate

A feature of Sedimentary rock is that it has layers.

Metamorphic

Metamorphic rocks were once igneous or sedimentary, but these rock were physically and chemically changed as a result of different temperatures and pressures. Metamorphic rocks do not melt otherwise they would form magma.

Examples of Metamorphic rocks are:

Slate

Schist

Gneiss

Marble