Magma = melted rock - forms deep in the Earth’s interior and buoyantly rises. If magma solidifies below the surface > intrusive igneous rock. If magma erupts on the surface > extrusive igneous rock. Melting and solidifying are part of the rock cycle.

Volcanism involves the eruption of molten rock called lava. Gases (H₂O, CO₂, S₂, H₂S) and solid material (ash, like Mount St. Helens) also erupt.

The process of crystallization involves atoms/ions becoming organized into 3-D crystals.