olivine science definition

An olive-green to brownish-green orthorhombic mineral. Olivine is a common mineral in the igneous rocks, such as basalt and gabbro, that make up most of the Earth's crust beneath the oceans. Chemical formula: (Mg,Fe)₂SiO₄.
♦ Olivine in which the mafic component consists entirely of magnesium is called forsterite . Chemical formula: Mg₂SiO₄.
♦ Olivine in which the mafic component consists entirely of iron is called fayalite . Chemical formula: Fe₂SiO₄.