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Ferrihydrite Mineral Data
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General Ferrihydrite Information
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 Chemical Formula: |
Fe+++2O3•0.5(H2O) |
| Composition: |
Molecular Weight = 168.70 gm |
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Iron 66.21 % Fe 94.66 % Fe2O3 |
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Hydrogen 0.60 % H 5.34 % H2O |
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Oxygen 33.19 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
| Empirical Formula: |
Fe3+2O3•0.5(H2O) |
| Environment: |
Secondary mineral in an oxidizing environment, strongly dependant on pH. |
| IMA Status: |
Approved IMA 1973 |
| Locality: |
Clara mine, Grube Clara, Germany Link to MinDat.org Location Data. |
| Name Origin: |
Named for the composition as a hydrated ferric iron compound. |
| Name Pronunciation: |
Ferrihydrite  |
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Ferrihydrite Image |
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Images:
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Ferrihydrite
Comments: Brown ferrihydrite.
Location: Fischersdorf, near Saalfeld, Thuringia, Germany.
Scale: Picture size 6 mm.
© Thomas Witzke |
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Ferrihydrite Crystallography
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| Axial Ratios: |
a:c = 1:3.17567 |
| Cell Dimensions: |
a = 2.96, c = 9.4, Z = 1; V = 71.33 Den(Calc)= 3.93 |
| Crystal System: |
Trigonal - Hexagonal Scalenohedral H-M Symbol (3 2/m) Space Group: P 31c |
| X Ray Diffraction: |
By Intensity(I/Io): 2.45(1), 1.97(0.6), 2.25(0.6), |
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Physical Properties of Ferrihydrite
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| Color: |
Yellow brown, Dark brown. |
| Density: |
3.8 |
| Habit: |
Aggregates - Made of numerous individual crystals or clusters. |
| Habit: |
Microscopic Crystals - Crystals visible only with microscopes. |
| Streak: |
yellowish brown |
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Optical Properties of Ferrihydrite
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| Optical Data: |
NCalc= 2.24 - from Gladstone-Dale relationship (KC = 0.3163) where Ncalc=Dcalc*KC+1
NCalc= 2.2 - from Gladstone-Dale relationship (KC = 0.3163) where Ncalc=Dmeas*KC+1
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Calculated Properties of Ferrihydrite
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| Electron Density: |
Bulk Density (Electron Density)=3.77 gm/cc
note: Specific Gravity of Ferrihydrite =3.93 gm/cc.
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| Fermion Index: |
Fermion Index = 0.01
Boson Index = 0.99 |
| Photoelectric: |
PEFerrihydrite = 20.08 barns/electron
U=PEFerrihydrite x rElectron Density= 75.77 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Ferrihydrite is Not Radioactive |
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Ferrihydrite Classification
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| Dana Class: |
04.03.02.02 (04)Simple Oxides |
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(04.03)with a cation charge of 3+ (A+++2 O3) |
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(04.03.02)Dana Group |
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04.03.02.01 Akdalaite 5(Al2O3)•(H2O) P 63mc 6mm |
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04.03.02.02 Ferrihydrite Fe2O3•0.5(H2O) P 31c 3 2/m |
| Strunz Class: |
04.FE.35 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate |
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04.F - Hydroxides (without V or U) |
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04.FE -Hydroxides with OH, without H2O; sheets of edge-sharing octahedra |
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04.FE.35 Ferrihydrite Fe2O3•0.5(H2O) P 31c 3 2/m |
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Other Ferrihydrite Information
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| References: |
PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) |
| See Also: |
Links to other databases for Ferrihydrite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
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Ferrihydrite
Fe+++2O3•0.5(H2O)
Dana No: 04.03.02.02 Strunz No: 04.FE.35
Locality:
Notes:
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