The ratio of magnesium to iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember: Mg2SiO4) and fayalite (Fe-endmember: Fe2SiO4).

Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and/or fayalite (Fa) (e.g., Fo70Fa30, or just Fo70 with Fa30 implied).

Olivine incorporates only minor amounts of elements other than oxygen (O), silicon (Si), magnesium (Mg) and iron (Fe).

It is also called chrysolite (or chrysolithe, from the Greek words for gold and stone), though this name is now rarely used in the English language.

Some of the finest gem-quality olivine has been obtained from a body of mantle rocks on Zabargad Island in the Red Sea.

[16] The metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content also produces Mg-rich olivine, or forsterite.

In contrast, Mg-rich olivine does not occur stably with silica minerals, as it would react with them to form orthopyroxene ((Mg,Fe)2Si2O6).

[18] Mg-rich olivine has also been discovered in meteorites,[19] on the Moon[20] and Mars,[21][22] falling into infant stars,[23] as well as on asteroid 25143 Itokawa.

[24] Such meteorites include chondrites, collections of debris from the early Solar System; and pallasites, mixes of iron-nickel and olivine.

They are also thought to influence the dynamics of mantle convection in that the exothermic transitions reinforce flow across the phase boundary, whereas the endothermic reaction hampers it.

It alters into iddingsite (a combination of clay minerals, iron oxides and ferrihydrite) readily in the presence of water.

[34] Norway is the main source of olivine in Europe, particularly in an area stretching from Åheim to Tafjord, and from Hornindal to Flemsøy in the Sunnmøre district.

Strøm wrote that in Norddal district large quantities of olivine were broken from the bedrock and used as sharpening stones.

[42] In Finland, olivine is marketed as an ideal rock for sauna stoves because of its comparatively high density and resistance to weathering under repeated heating and cooling.

[44][45] A nonprofit, Project Vesta, is investigating this approach on beaches which increase the agitation and surface area of crushed olivine through wave action.