forsterite

{{Infobox mineral | name = Forsterite | category = Nesosilicates | boxwidth = | boxbgcolor = | image = Forsterite on Sanidine - Ochtendung, Eifel, Germany.jpg | imagesize = 260px | caption = Forsterite (big tabular and colorless) on sanidine (little colorless crystals)with hematite (reddish) | formula = Magnesium silicate (Mg2SiO4) | IMAsymbol = Fo | molweight = | strunz = 9.AC.05 | system = Orthorhombic | class = Dipyramidal (mmm) H-M Symbol: (2/m 2/m 2/m) | symmetry = Pbnm | unit cell = a = 4.7540 Å, b = 10.1971 Å c = 5.9806 Å; Z = 4 | color = Colorless, green, yellow, yellow green, white | habit = Dipyramidal prisms often tabular, commonly granular or compact massive | twinning = On {100}, {011} and {012} | cleavage = Perfect on {010} imperfect on {100} | fracture = Conchoidal | mohs = 7 | luster = Vitreous | refractive = nα = 1.636 – 1.730 nβ = 1.650 – 1.739 nγ = 1.669 – 1.772 | opticalprop = Biaxial (+) | birefringence = δ = 0.033 – 0.042 | pleochroism = | 2V = 82° | streak = White | gravity = 3.21 – 3.33 | density = | melt = 1890 °C | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent to translucent | other = | references = }} Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich end-member of the olivine solid solution series. It is isomorphous with the iron-rich end-member, fayalite. Forsterite crystallizes in the orthorhombic system (space group Pbnm) with cell parameters a 4.75 Å (0.475 nm), b 10.20 Å (1.020 nm) and c 5.98 Å (0.598 nm).

Forsterite is associated with igneous and metamorphic rocks and has also been found in meteorites. In 2005 it was also found in cometary dust returned by the Stardust probe. In 2011 it was observed as tiny crystals in the dusty clouds of gas around a forming star.