Igneous rocks are rocks formed from molten magma. The material is made liquid by the heat inside the Earth’s mantle.
Igneous rock occurs in two ways.
- Slow cooling :
Igneous rock formed from magma that has become solid inside the earth is called intrusive igneous rock. Examples of intrusive igneous rock types are gabbro, diorite, and granite.
- Fast cooling :
Igneous rock formed from lava that has become solid on the outside of the Earth is called extrusive igneous rock. This can happen because of the eruption of a volcano. Some extrusive igneous rock types are basalt, andesite, rhyolite, tuff, obsidian, and pumice.