The crust consists of lightweight metal oxide silicates. In between these two extremes is the mantle, composed of heavier metal oxide silicates than crustal material. Thus, the core is made up of much different material than the crust, and the mantle consists of significantly different material than either. Earth's inaccessible core thousands of kilometers down would be a miner's dream if it were accessible, but we have to settle for what is available in the crust, and the deepest mines are only a few kilometers deep. For example, the Earth's crust has a maximum thickness of less than roughly 100 kilometers, whereas its mantle is 2,800 kilometers thick and its core is about 3,500 kilometers in radius.
Chemical fractionation is the formation of certain most stable minerals.
These clumps are called minerals. A mineral is a homogenous solid substance having a definite chemical composition, crystalline structure, color and hardness. Mg 2 SiO 4 . Then chemical fractionation further occurs among the localized materials. In hot or molten bodies, the elements can most easily migrate randomly and over time congregate with those other elements and minerals which they are most compatible with.