The mineral olivine is a magnesium iron silicate, thus it is a type of nesosilicate or orthosilicate. It is a common mineral in the Venture's subsurface but weathers quickly on the surface.
The ratio of magnesium and iron varies between the two endmembers of the solid solution series: forsterite and fayalite. Compositions of olivine are commonly expressed as molar percentages of forsterite and fayalite. Forsterite has an unusually high melting temperature at atmospheric pressure, almost 1,900 °C (3,450 °F), but the melting temperature of fayalite is much lower (about 1,200 °C [2,190 °F]). The melting temperature varies smoothly between the two endmembers, as do other properties.
Oxygen, silicon, magnesium and iron can be found incoporated into Olivine. Manganese and nickel commonly are the additional elements present in highest concentrations. Olivine gives its name to the group of minerals with a related structure (the olivine group) which includes tephroite, monticellite and kirschsteinite.
Olivine gemstones are called peridot and chrysolite.