Igneous rock



Igneous rock (derived from the Latin word ignis meaning fire), or magmatic rock is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava.

Types of igneous rocks
Igneous rocks can be classified into two types:

Intrusive igneous rocks
Intrusive igneous rocks form below the Earth's surface, and the slow cooling that occurs there allows large crystals to form.

Extrusive igneous rocks
Extrusive igneous rocks erupt onto the surface, where they cool to form small crystals. Some cool so quickly that they form amorphous glass.