Forsterite
Forsterite (peridot) crystal captured in space by NASA's Stardust spacecraft.
General
Category	Mineral
Chemical formula	Magnesium silicate (Mg2SiO4)
Identification
Color	Green to yellow
Crystal system	Orthorhombic
Cleavage	{010}, {100} - imperfect
Fracture	Conchoidal
Mohs Scale hardness	7
Luster	Vitreous
Refractive index	α = 1.635, β = 1.651, γ = 1.670
Specific gravity	3.222

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 Å, b 10.20 Å and c Å 5.98. Peridot (pronounced pear-uh-dot or pear-uh-doe, IPA: /pɛɹɪdɑːt/ or Fr. ... For other uses, see NASA (disambiguation). ... Stardust may refer to several concepts: In space and aviation: another name for cosmic dust Stardust (spacecraft), a comet coma sample return spacecraft Star Dust (aeroplane), a British airliner that vanished in 1947 In music: Stardust (song), a 1927 jazz-pop song by Hoagy Carmichael Stardust (album), a record album... Minerals are natural compounds formed through geological processes. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance as coarse powder, dark gray with bluish tinge Atomic mass 28. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... A fracture is the separation of a body into two, or more, pieces under the action of stress. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index (or index of refraction) of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a vacuum. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Olivine basalt The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... The space group of a crystal is a mathematical description of the symmetry inherent in the structure. ...

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. An artists rendering of Stardust (NASA image) Stardust is an American interplanetary spacecraft launched on February 7, 1999. ... Johann Reinhold Forster Johann Reinhold Forster and Georg Forster in Tahiti, by John Francis Rigaud (1742-1810), 1780. ...

The gemstone variety of Forsterite is known as Peridot. Peridot (pronounced pear-uh-dot or pear-uh-doe, IPA: /pɛɹɪdɑːt/ or Fr. ...

Forsterite reacts with quartz to form the orthopyroxene mineral enstatite in the following reaction: Quartz is one of the most common minerals in the Earths continental crust. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... The pyroxene silicate minerals enstatite (MgSiO3) and ferrosilite (FeSiO3) form a complete solid solution series and are common rock-forming minerals found in igneous and metamorphic rocks and meteorites. ...

Mg₂SiO₄ + SiO₂ → 2MgSiO₃.

References

• Deer, W. A., Howie, R. A., and Zussman, J. (1992). An introduction to the rock-forming minerals (2nd ed.). Harlow: Longman ISBN 0-582-30094-0
• Amethyst Galleries' Mineral Gallery