How do the crystallization and settling of the earliest formed minerals affect the composition of the remaining magma?

The process of crystallization comprises of two main steps:
1. Nucleation
2. Growth

When the early setting minerals have crystallized, they provide a surface for the remaining minerals in the magma to crystallize. They do this by providing a surface for the nucleation to occur. Once nucleation has occurred, the crystals grow in size.

The angle of reflection is 30°