olivine

noun

1. Mineralogy. any of a group of magnesium iron silicates, (Mg,Fe)2SiO4, occurring in olive-green to gray-green masses as an important constituent of basic igneous rocks.

noun

1. an olive-green mineral of the olivine group, found in igneous and metamorphic rocks. The clear-green variety (peridot) is used as a gemstone. Composition: magnesium iron silicate. Formula: (MgFe) 2 SiO 4 . Crystal structure: orthorhombicAlso called: chrysolite
2. any mineral in the group having the general formula (Mg,Fe,Mn,Ca) 2 SiO 4

1. 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.