Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich end-member solid solution series. It is isomorphous with the iron-rich end-member, fayalite system (space group Pbnm) with cell parameters a 4.75 Å ), b 10.20 Å (1.020 nm) and c 5.98 Å (0.598 nm).
Forsterite is associated with igneous and metamorphic rocks. 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.
Two polymorphs of forsterite are known: wadsleyite (also orthorhombic) and ringwoodite (isometric). Both are mainly known from meteorites.
Peridot variety of forsterite olivine.