Forsterite
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Forsterite 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 with cel
Forsterite (big tabular and colorless) on sanidine (little colorless crystals) with hematite (reddish)
Orange forsterite with a portion of tephroite
Forsterite var. peridot with minor pyroxene (brown) on vesicular basalt. Collected near Peridot, Arizona.
Peridot
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Peridot, sometimes called chrysolite, is a yellow-green transparent variety of olivine, specifically the magnesium rich end member called forsterite. Peridot is one of the few gemstones that occur in
Forsterite
…of forsterite are known: wadsleyite (also orthorhombic) and ringwoodite (isometric, cubic crystal system). Both are mainly known from meteorites. Peridot is the gemstone variety of forsterite olivine. Pure forsterite is composed of magnesium, oxygen and silicon. The chemical formula is Mg2SiO4. Forsterite…
Pallasite meteorite with olive-green peridot crystals, found in Fukang, China.
Due to its high birefringence, doubling of facet junctions is commonly seen when viewing peridot under magnification.