Igneous rocks are formed through the cooling and solidification of magma or lava. This process can occur either below the Earth’s surface or on the surface itself.
When magma cools slowly beneath the Earth’s crust, it forms intrusive igneous rocks. These rocks have larger crystals due to the slow cooling process, which allows more time for crystal growth. Examples of intrusive igneous rocks include granite and diorite.
On the other hand, when lava erupts onto the Earth’s surface and cools quickly, it forms extrusive igneous rocks. These rocks have smaller crystals or even a glassy texture because the rapid cooling doesn’t allow much time for crystal formation. Examples of extrusive igneous rocks include basalt and pumice.
In summary, igneous rocks are formed from the cooling and solidification of molten material, and the rate of cooling determines the texture and crystal size of the resulting rock.