Mineralogy Database

Ferrihydrite Mineral Data

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General Ferrihydrite Information

Help on Chemical  Formula: Chemical Formula: Fe+++2O3•0.5(H2O)
Help on Composition: Composition: Molecular Weight = 168.70 gm
   Iron      66.21 %  Fe   94.66 % Fe2O3
   Hydrogen   0.60 %  H     5.34 % H2O
   Oxygen    33.19 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Fe3+2O3•0.5(H2O)
Help on Environment: Environment: Secondary mineral in an oxidizing environment, strongly dependant on pH.
Help on IMA Status: IMA Status: Approved IMA 1973
Help on Locality: Locality: Clara mine, Grube Clara, Germany Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the composition as a hydrated ferric iron compound.
Help on Name Pronunciation: Name Pronunciation: Ferrihydrite Say FERRIHYDRITE

Ferrihydrite Image

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Comments: Brown ferrihydrite.
Location: Fischersdorf, near Saalfeld, Thuringia, Germany. Scale: Picture size 6 mm.
© Thomas Witzke

Ferrihydrite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:3.17567
Help on Cell Dimensions: Cell Dimensions: a = 2.96, c = 9.4, Z = 1; V = 71.33 Den(Calc)= 3.93
Help on Crystal System: Crystal System: Trigonal - Hexagonal Scalenohedral H-M Symbol (3 2/m) Space Group: P 31c
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.45(1), 1.97(0.6), 2.25(0.6),

Physical Properties of Ferrihydrite

Help on Color: Color: Yellow brown, Dark brown.
Help on Density: Density: 3.8
Help on Habit: Habit: Aggregates - Made of numerous individual crystals or clusters.
Help on Habit: Habit: Microscopic Crystals - Crystals visible only with microscopes.
Help on Streak: Streak: yellowish brown

Optical Properties of Ferrihydrite

Help on Optical Data: 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

Calculated Properties of Ferrihydrite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.77 gm/cc
note: Specific Gravity of Ferrihydrite =3.93 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEFerrihydrite = 20.08 barns/electron
U=PEFerrihydrite x rElectron Density= 75.77 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Ferrihydrite is Not Radioactive

Ferrihydrite Classification

Help on  Dana Class: Dana Class: (04)Simple Oxides
  (04.03)with a cation charge of 3+ (A+++2 O3)
  (04.03.02)Dana Group Akdalaite 5(Al2O3)•(H2O) P 63mc 6mm Ferrihydrite Fe2O3•0.5(H2O) P 31c 3 2/m
Help on  Strunz Class: Strunz Class: 04.FE.35 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate
  04.F - Hydroxides (without V or U)
  04.FE -Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
04.FE.35 Ferrihydrite Fe2O3•0.5(H2O) P 31c 3 2/m

Other Ferrihydrite Information

Help on References: References: PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: 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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Dana No: Strunz No: 04.FE.35





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