Olivine is a magnesium iron silicate with the formula (Mg²⁺, Fe²⁺)₂SiO₄. End members are forsterite (Mg2SiO₄) and fayalite (Fe²⁺₂SiO₄). Olivine is an abundant mineral in most mafic igneous rocks and the most abundant mineral in the earth’s upper mantle. It has an orthorhombic crystal system.

Distribution

The olivine group is commonly found in igneous rock and basalts. Olivine is mined for the gem peridot. Olivine is vulnerable to weathering and is not commonly found in soil, despite the igneous parent material. Artificial weathering of olivine to produce alkalinity to sequester carbon dioxide as magnesium carbonate has been proposed as a means of carbon sequestration. Olivine has been discovered on the surface of Mars.