The second most abundant element in the Earth’s crust other than oxygen is silicon which if by mass is around 25.7g or 23%. However in nature, silicon never exist as a free or pure element but instead it mostly combines with the most abundant element in the Earth’s crust, oxygen, hence producing silica (SiO₂) or silicate minerals. The most prominent charge of Si in the crust is +4 rather than +2 which involve a silicon atom to bond in a tetrahedral manner with 4 other oxygen atoms giving rise to the silica tetrahedron structure that has a charge of -4. The major source for silicon is actually the magma which is produced by the partial melting of the upper mantle and crust that produces various types of magmas and the most predominant on Earth is silicate magma compare to the extremely rare carbonatite magma.
