Constituent
- Name
- Goethite
- IMA name
- Goethite
- Class
- non-silicate mineral
- Compound type
- oxide-hydroxide
- Comments
- Goethite is mixed locally with kaolinite
- Relevance
- main - major
- Arrangement
- heterogeneous in multi-phases
- Abundance comments
- locally present in kaolinite
- Formula
- $FeO(OH)$
- Chemical formula
- FeO(OH)
- Elemental formula
- (Fe3+) O H (O-)
- Isotope mixture type
- terrestrial abundance
- Oxides
-
Formula $Fe_{2}O_{3}$ $H_{2}O$ Mass fraction (%) 89.86 10.14
Strunz
- Class
- oxides - hydroxides - arsenites (04)
- Division
- hydroxides (without V or U) (04.F)
- Family
- Hydroxides with OH, without H2O; chains of edge-sharing octahedra (04.FD)
- Code
- 04.FD.10
Dana
- Major class
- oxides and hydroxides (III)
- Class
- hydroxides and oxides containing hydroxyl (06)
- Type
- where X+++O OH (06.01)
- Group
- Diaspore group (Orthorhombic, Pnma or Pnmd) (06.01.01)
- Code
- 06.01.01.02
- Phase name
- alpha-FeO(OH)
- Phase type
- crystalline
- Crystal system
- orthorhombic
- Crystal class
- dipyramidal
- Crystal class symbol
- mmm (D2h)
- Crystal spacegroup
- Pnma
- Molar mass
- 88.85 $g/mol$
- Density
- 3.3 - 4.3 $g/cm^3$
- Refringence type
- biaxial
- Refringence sign
- negative
- Birefringence
- 0.138 - 0.24
- Refraction index $n_{\alpha}$
- 2.26 - 2.275
- Refraction index $n_{\beta}$
- 2.393 - 2.409
- Refraction index $n_{\gamma}$
- 2.398 - 2.515
- Dispersion V
- 0 - 27
- Color
- brown, reddish brown, yellowish brown, brownish yellow
- Diaphaneity
- subtranslucent to opaque