Constituent
- Name
- olivine
- IMA name
- Fayalite-Forsterite series
- Class
- silicate mineral
- Compound type
- nesosilicate
- Comments
- Equivalent Space Group: Pbnm (62)
- Relevance
- main - major
- Arrangement
- single phase
- Mass fraction
- 1.0
- Formula
- $(Fe^{2+}_x,Mg_{1-x})_2.SiO_4 \ \ \ \ \ $ where $x=0-1$
- Chemical formula
- (Fe2+,Mg)2SiO4
- Elemental formula
- (Fe2+)0-2 (Mg)0-2 Si O4
- Isotope mixture type
- terrestrial abundance
- Composition comments
- perfect solid solution - Common impurities: Mn, Ni
- Oxides comments
- FeO de 0 à 70.5%, MgO de 0 à 57.3%, SiO2 de 29.5 à 42.7%
Strunz
- Class
- silicates (09)
- Division
- nesosilicate (09.A)
- Family
- without additional anions; cations in octahedral [6] coordination (09.AC)
- Code
- 09.AC.05
Dana
- Major class
- silicates (VIII)
- Class
- nesosilicate insular SiO4 groups only (51)
- Type
- with all cations in octahedral [6] coordination (51.03)
- Group
- Olivine group (51.03.01)
- Code
- 51.03.01.00
- Phase type
- crystalline
- Crystal system
- orthorhombic
- Crystal class
- dipyramidal
- Crystal class symbol
- mmm (D2h)
- Crystal spacegroup
- Pnma
- Molar mass
- 140.69 - 203.78 $g/mol$
- Density
- 3.21 - 4.39 $g/cm^3$
- Refringence type
- biaxial
- Refringence sign
- negative
- Birefringence
- 0.0330 - 0.0510
- Refraction index $n_{\alpha}$
- 1.636 - 1.824
- Refraction index $n_{\beta}$
- 1.65 - 1.864
- Refraction index $n_{\gamma}$
- 1.669 - 1.875
- Color
- colorless, brown, green, yellow, yellow green, white, black
- Diaphaneity
- transparent to translucent
- Luster
- vitreous