Forsterite (Mg2SiO4) is the magnesium rich end-member of the olivine solid-solution series. Forsterite crystallizes in the orthorhombic system (space group Pbnm) with cell parameters a 4.75 , b 10.20 and c 5.98. Forsterite is associated with igneous rocks and has also been found in some iron meteorites. In 2005 it was also found in cometary dust returned by the Stardust probe. It is named after German naturalist Johann Forster. The gemstone variety of forsterite is known as peridot. Forsterite reacts with quartz to form the orthopyroxene mineral enstatite in the following reaction: Mg2SiO4 + SiO2 ? 2MgSiO3.