Any of a group of silicate
minerals which are orthosilicates of magnesium and iron (Mg, Fe)2SiO4.
Olivine forms olive-green crystals in the orthorhombic system, and occurs
commonly in igneous rock, chiefly basalt,
gabbro, and peridotite.
The transparent variety peridot is used
as a gemstone. Olivine is also found in
some meteorites, such as carbonaceous chondrites.
AND PLANETARY SCIENCE