Ferrihydrite (original) (raw)
A valid IMA mineral species
About FerrihydriteHide
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Previously given as Fe3+5O3(OH)9.
Colour:
Dark brown, yellow-brown
Name:
For the chemical composition (hydrated ferric iron oxide).
The Fe analogue of akdalaite.
A poorly crystalline nanomineral built up of about 20% (FeO4) and 80% (FeO6) polyhedra. It forms by rapid oxidation and hydrolysis, and exists in varying degrees of structure disorder; the two extremes are the so-called 2-line and 6-line ferrihydrites (distinguished by their X-ray powder diffraction patterns). It is a metastable nanomineral precursor to other minerals, e.g. hematite, goethite. There are no known deposits of ferrihydrite before the Pleistocene.
Two structure models have been proposed: the "f-phase" model and the "akdalaite" model; the first one seems to be correct (Paktunc et al., 2013).
Some lichen (e.g., Pertusaria corallina, Stereocaulon vulcani) may induce ferrihydrite formation on lava flows and basalt- and gabbro- hosted olivine and also on augite (see Burford et al., 2003).
The iron bacteria, especially Gallionella ferruginea, Leptothrix ochracea and Toxothrix trichogenes create ferrihydrite as a waste product of their metabolism.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:1493:5
302b6c6b-9dfa-4294-8b2e-6074a8623f05
IMA Classification of FerrihydriteHide
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Type description reference:
Classification of FerrihydriteHide
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4.FE.35
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
4.3.2.2
4 : SIMPLE OXIDES
3 : A2X3
7.20.9
7 : Oxides and Hydroxides
20 : Oxides of Fe
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Fhy | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Fhy | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of FerrihydriteHide
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Colour:
Dark brown, yellow-brown
Density:
3.96 g/cm3 (Measured)
Comment:
Synthesized material
Chemistry of FerrihydriteHide
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Mindat Formula:
Fe3+10O14(OH)2
Previously given as Fe3+5O3(OH)9.
Crystallography of FerrihydriteHide
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Cell Parameters:
a = 5.08 Å, c = 9.4 Å
Unit Cell V:
210.08 ų (Calculated from Unit Cell)
Comment:
Point Group: n.d.; Space Group: n.d.
Crystal StructureHide
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| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0012028 | Ferrihydrite | Jansen E, Kyek A, Schafer W, Schwertmann U (2002) The structure of six-line ferrihydrite Applied Physics A74 S1004-S1006 | 2002 | synthetic | 0 | 293 | |
| 0012029 | Ferrihydrite | Jansen E, Kyek A, Schafer W, Schwertmann U (2002) The structure of six-line ferrihydrite Applied Physics A74 S1004-S1006 | 2002 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder DiffractionHide
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Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.50 Å | (100) |
| 2.21 Å | (80) |
| 1.96 Å | (80) |
| 1.48 Å | (80) |
| 1.51 Å | (70) |
| 1.72 Å | (50) |
Geological EnvironmentHide
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Geological Setting:
Cold-water springs, Mine workings, warm subsea springs, warm water seabed, thermal springs, thermal water in brooks, rivers and lakes.
Type Occurrence of FerrihydriteHide
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General Appearance of Type Material:
As poorly crystalline spheres, to 50 µm
Place of Conservation of Type Material:
Vernadsky Geological Musem, Moscow, 51508; A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 76642.
Associated Minerals at Type Locality:
Reference:
Chukhrov, F.V., Zvyagin, B.B., Gorshkov, A.I., Yermilova, L.P., Balashova, V.V. (1973) Ferrihydrite. Izvestiya Akademii Nauk SSSR, Seriya Geologicheskaya: 1973(4): 23-33.
Synonyms of FerrihydriteHide
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Other Language Names for FerrihydriteHide
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Varieties of FerrihydriteHide
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| Arsenical ferrihydrite | As-bearing variety.Relatively common as a weathering product of arsenopyrite. |
|---|---|
| Melanosiderite | Melanosiderite was described by Cooke (1875) as a hydrated basic ferric silicate. Examination of a specimen from the type locality and corresponding to the original description (BM66908), by energy-dispersive microanalysis, infrared spectroscopy, and X-ra... |
Relationship of Ferrihydrite to other SpeciesHide
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Other Members of this group:
Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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Other InformationHide
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Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for FerrihydriteHide
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References for FerrihydriteHide
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Reference List:
Localities for FerrihydriteHide
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This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the 
symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Locality ListHide
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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. 
- Good crystals or important locality for species. 
- World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.