Britannica Sources used in this answer

How does silicon occur in Earth’s mantle?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A periodic table element square for silicon shows atomic number 14, symbol Si, atomic weight range, electron configuration, and name. Icons indicate it is a solid nonmetal with diamond crystal structure and equal relative strength. Labels explain each property. — silicon Chemical properties of the element silicon.

In Earth’s mantle, silicon occurs primarily in combination with oxygen and other elements as silicate minerals. During the early geochemical differentiation of the planet, silicon—along with magnesium—exhibited a strong affinity for oxygen, leading it to combine completely with oxygen to form these compounds.12

The mantle is composed largely of magnesium-iron silicates, specifically olivine and pyroxene, or their high-pressure equivalents. These minerals serve as critical structural components of the mantle, distinguishing it from the crust, which is enriched in elements that do not readily enter the crystal structures of these specific silicate minerals.2