solid solution series
Olivine (or chrysolite) is a silicate mineral made of magnesium iron silicate with the formula (Mg,Fe)2SiO4.
It ranges in colour from chartreuse green to pale olive. In its gem form, it is called peridot.
Dunite is a rock of 90%+ olivine. Dunite and other peridotite rocks are major constituents of the Earth's mantle above a depth of about 400 kilometers. Dunite is rarely found on land, except where slabs of mantle rock from a subduction zone have been thrust onto continental crust. Olivine has also been found at several extraterrestrial locations, such as the moon and many passing space rocks - as well as the outer layers of dust orbiting young stars.