Constituent
Name
akaganeite
IMA name
Akaganeite
Class
non-silicate mineral
Compound type
oxide-hydroxide
Comments
formula given as $Fe^{3+}(O,OH,Cl)$ in Webmineral
Constituent abundance in material
Relevance
main - major
Arrangement
single phase
Mass fraction
1.0
Chemical composition
Formula
$(Fe^{3+},Ni^{2+})_8(OH,O)_16Cl_1.25 /bullet nH2O$
Chemical formula
(Fe3+,Ni2+)8(OH,O)16Cl1.25 • nH2O
Elemental formula
(Fe3+) O H (O-)
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Fe^{3+}$ Iron(III) cation element 7 - 8 constituent cation main
$Ni^{2+}$ Nickel cation element 0 - 1 constituent cation main
$(OH)^-$ Hydroxide anion chemical function 9 - 10 anionic radical main
$O^{2-}$ Oxide anion element 6 - 7 constituent anion main
$Cl^-$ Chloride anion element 1.2 - 1.3 constituent anion main
Composition comments
Ni may possibly be > 1
Chemical functions
  Function Number
$(OH)^-$ 1
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $Fe_{2}O_{3}$ $NiO$ $H_{2}O$ $Cl$
Mass fraction (%) 79.7 3.92 11.48 6.05

Strunz

Class
oxides - hydroxides - arsenites (04)
Division
metal:oxygen = 1:2 and similar (04.D)
Family
with large (+/- medium-sized) cations; tunnel structures (04.DK)
Code
04.DK.05

Dana

Major class
oxides and hydroxides (III)
Class
hydroxides and oxides containing hydroxyl (06)
Type
where X+++O OH (06.01)
Group
-Akaganeite- group (06.01.06)
Code
06.01.06.01
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
P2/m
Comments
Effective space group: I2/m
Molar mass
761.37 $g/mol$
Density
3.52 - 3.55 $g/cm^3$
Refringence type
biaxial
Refraction index $n_{\alpha}$
1.99 - 2.19 (calc.)
Color
brown, rusty brown
Diaphaneity
transparent to opaque