Crust Formation 

New crust is created through tectonic processes caused through upwelling convection currents in the mantle, driven finally through heat from radioactive decay of elements in the Earth. The melting of rocks and consequent recrystallization leads to fractionation of a few lithophilic elements. Magnesium tends to stay in the mantle and along with it some other compatible elements that form ions of quite identical charge and size to Mg²⁺ (example Fe²⁺ and Cr³⁺).

Incompatible elements (example Na, K, Ti) do not stay with the magnesium silicate but pass simply into the melt and therefore are more concentrated in crustal rocks.

Where the rocks of the mantle consist of mostly orthosilicates with nonpolymerized SiO^4-₄ ions, and chain silicates like MgSiO₃, the minerals of the crust mainly consist of more highly polymerized silicate units. A few of the most common crustal rocks are feldspars, three-dimensional structure silicates consisting of corner-sharing [SiO₄] groups, like SiO₂ but with some Si is replaced through Al. A few idealized formulae are KAlSi₃O₈ and CaAl₂Si₂O₈, although in reality these minerals are very much complex, with several other elements exist in small concentrations.

Several less common elements (example Ga and Ge) are incorporated to a number of extent into the crystal structures of main minerals, and so might be rather thinly spread over the crust. Others are concentrated through forming individual minerals. Native gold and cinnabar (HgS) were identified in antiquity even though Au and Hg are very uncommon elements. Alternatively, the less rare Ga and Ge were not revealed until the late 19th century.

The chemical processes leading to dissimilar minerals are diverse. Highly incompatible lithophilic elements are (example Li, Be, Zr and lanthanides) determined in the final stages of solidification of molten rocks, identified as pegmatites. several sulfide minerals (example of Cu, Zn, Mo and Pb) are formed through hydrothermal processes, where water circulates deep within the crust and at high pressures and temperatures, and creates soluble complexes of these elements with anions like Cl^- and HS^-, that might subsequently precipitate solids when they cool.