Constituent
Name
iddingsite
Class
silicate mineral
Compound type
silicate
Relevance
main - major
Arrangement
heterogeneous in multi-phases
Formula
$MgOFe_2O_3 3SiO_2 \bullet 4(H_2O)$
Chemical formula
MgO Fe2O3 3SiO2 •n(H2O)
Elemental formula
Mg (Fe2+)2 Si3 O10
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Mg$ Magnesium element 1 constituent element main
$Fe^{2+}$ Iron(II) cation element 2 constituent element main
$Si$ Silicon element 3 constituent element main
$O$ Oxygen element 10 constituent element main
Oxides
Formula $MgO$ $FeO$ $SiO_{2}$ $H_{2}O$
Mass fraction (%) 8.91 31.77 39.85 15.93

Strunz

Class
silicates (09)
Division
unclassified silicates (09.H)
Family
Unclassified Silicate (09.HX)
Code
09.HX.00

Dana

Major class
silicates (VIII)
Class
unclassified silicates (78)
Type
Without Dana Classification Numbers (78.00)
Group
Unclassified Silicate (78.00.00)
Code
78.00.00.00
Phase type
crystalline
Crystal system
orthorhombic
Crystal class
unknown
Crystal class symbol
unknown
Crystal spacegroup
unknown
Texture
polycrystalline
Molar mass
452.31 $g/mol$
Density
2.5-2.8 $g/cm^3$
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.040 - 0.050
Refraction index $n_{\alpha}$
1.67 - 1.73
Refraction index $n_{\beta}$
1.7 - 1.76
Refraction index $n_{\gamma}$
1.72 - 1.77
Dispersion V
relatively strong
Color
brown
Diaphaneity
transparent to translucent
Luster
vitreous