The core is made up of free metal, predominantly iron and nickel. 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. For example, the Earth's crust has a maximum thickness of 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 . Olivine on Earth is mainly found not in the crust but in the mantle. Redder dirt is richer in iron silicates and oxides.