1. Magmatic crystallization: This is the process where molten rock, known as magma, cools and solidifies. This can happen either underground (intrusive igneous rocks) or on the surface (extrusive igneous rocks).
2. Volcanic eruption: This is the process where magma erupts onto the Earth's surface as lava. The lava then cools and solidifies, forming extrusive igneous rocks.
So, both cooling and solidification of magma are key to forming igneous rocks, whether it happens below or above ground.
