Crystal Settling & Magmatic Differentiation

In this animation, redder colors indicate higher silica content. Note that because the crystals that are forming have lower silica than the magma (at every point in time), that the magma gets progressively more silica rich.

Not shown: early-formed crystals will often react with the magma around them to later-forming crystals, producing (for example) olivine crystals with a rim of pyroxene.