Constituent
- Name
- Ferrihydrite
- IMA name
- Ferrihydrite
- Class
- non-silicate mineral
- Compound type
- oxide-hydroxide
- Comments
- nanophase (< 20 nm) ferric oxide particles
- Formula
- $Fe^{3+}_2O_3 \bullet 0.5(H_2O)$
- Chemical formula
- (Fe3+)2O3•0.5(H2O)
- Elemental formula
- (Fe3+)2 O3.5 H
- Isotope mixture type
- terrestrial abundance
- Oxides
-
Formula $Fe_{2}O_{3}$ $H_{2}O$ Mass fraction (%) 94.66 5.34
Strunz
- Class
- oxides - hydroxides - arsenites (04)
- Division
- hydroxides (without V or U) (04.F)
- Family
- Hydroxides with OH, without H2O; sheets of edge-sharing octahedral (04.FE)
- Code
- 04.FE.35
Dana
- Major class
- oxides and hydroxides (III)
- Class
- simple oxides (04)
- Type
- with a cation charge of 3+ (A+++2O3) (04.03)
- Group
- -Ferrihydrite- group (04.03.02)
- Code
- 04.03.02.02
- Phase type
- crystalline
- Crystal system
- trigonal
- Crystal class
- ditrigonal-scalenohedral
- Crystal class symbol
- -3m (D3d)
- Crystal spacegroup
- P-31c
- Texture
- nanocrystalline
- Molar mass
- 168.70 $g/mol$
- Density
- 3.8 - 3.93 $g/cm^3$
- Refringence type
- unknown
- Refringence sign
- unknown
- Color
- yellow brown, dark brown
- Diaphaneity
- opaque
- Luster
- unknown