Lepidocrocite Mineral Data
General Lepidocrocite Information
Chemical Formula:
FeO(OH)
Composition:
Molecular Weight = 88.85 gm
Iron 62.85 % Fe 89.86 % Fe2 O3
Hydrogen 1.13 % H 10.14 % H2 O
Oxygen 36.01 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Fe3+ O(OH)
Environment:
Common in iron ore deposits.
IMA Status:
Valid Species (Pre-IMA) 1813
Locality:
Common world wide. Link to MinDat.org Location Data.
Name Origin:
From the Greek lipis - "scale" and krokis - "fibre."
Name Pronunciation:
Lepidocrocite + Pronunciation
Synonym:
Esmeraldaite
Esmeraldite
Hydrohematite
ICSD 27846
PDF Aug-98
Lepidocrocite Image
Images:
Lepidocrocite
Comments: Translucent, red-brown crystals of lepidocrocite lining cavities in gossan matrix.
Location: Eisenzecher Zug Mine, Eiserfeld, Siegen District, North Rhine-Westphalia, Germany.
Scale: 7x5x3 cm.
© John Betts - Fine Minerals
Lepidocrocite Crystallography
Axial Ratios:
a:b:c =0.3087:1:0.2448
Cell Dimensions:
a = 3.86, b = 12.5, c = 3.06, Z = 4; V = 147.65 Den(Calc)= 4.00
Crystal System:
Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Amam
X Ray Diffraction:
By Intensity(I/Io ): 6.26(1), 3.29(0.9), 2.47(0.8),
Forms:
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Physical Properties of Lepidocrocite
Cleavage:
{010} Perfect
Color:
Red, Yellowish brown, Blackish brown.
Density:
4
Diaphaneity:
Opaque
Fracture:
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit:
Fibrous - Crystals made up of fibers.
Habit:
Pulverulent - Forms a loose, poorly-coherent powdery mass.
Habit:
Scaly - Morphology like fish scales.
Hardness:
5 - Apatite
Luminescence:
Non-fluorescent.
Luster:
Sub Metallic
Streak:
dark yellow brown
Optical Properties of Lepidocrocite
Gladstone-Dale:
CI meas = 0.042 (Good) - where the CI = (1-KPDmeas /KC ) CI calc = 0.042 (Good) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.3042,KPDmeas = 0.3042,KC = 0.3175 Ncalc = 2.27
Optical Data:
Biaxial (+), a=1.94, b=2.2, g=2.51, bire=0.5700, 2V(Calc)=84, 2V(Meas)=83. Dispersion relatively weak.
Pleochroism (x):
colorless or yellow.
Pleochroism (y):
orange or dark red orange.
Pleochroism (z):
orange or darker red orange.
RL Anisotrophism:
Strong.
RL Bireflectance:
Strong.
RL Color:
Light gray.
Reflectivity
Standardized Intensity (100%) Reflection Spectra of Lepidocrocite in Air
λ
R1
R 2
∑ R1 (λ)
∑ R2 (λ)
400 nm
13.00
21.40
420 nm
12.70
20.30
440 nm
12.40
19.20
460 nm
12.00
18.60
480 nm
11.70
18.10
500 nm
11.40
17.80
520 nm
11.20
17.40
540 nm
11.00
17.00
560 nm
10.80
16.50
580 nm
10.70
16.00
600 nm
10.60
15.70
620 nm
10.50
15.40
640 nm
10.40
15.20
660 nm
10.40
15.10
680 nm
10.40
15.00
700 nm
10.40
14.90
Calculated Relative Intensity Colors of Lepidocrocite in Air
Relative Intensity
0%
90%
100%
180%
270%
360%
450%
540%
630%
720%
810%
820%
R1
R2
Calculated Properties of Lepidocrocite
Electron Density:
Bulk Density (Electron Density)=3.87 gm/cc note: Specific Gravity of Lepidocrocite =4.00 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PELepidocrocite = 18.93 barns/electronU=PELepidocrocite x r Electron Density= 73.29 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Lepidocrocite is Not Radioactive
Lepidocrocite Classification
Dana Class:
06.01.02.02 (06) Hydroxides and Oxides Containing Hydroxyl
(06.01) where X+++O OH
(06.01.02) Boehmite Group
06.01.02.01 Boehmite AlO(OH) Amam 2/m 2/m 2/m
06.01.02.02 Lepidocrocite FeO(OH) Amam 2/m 2/m 2/m
06.01.02.03 Guyanaite CrO(OH) Pnnm 2/m 2/m 2/m
Strunz Class:
04.FE.15 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.15 Boehmite AlO(OH) Amam 2/m 2/m 2/m
04.FE.15 Lepidocrocite FeO(OH) Amam 2/m 2/m 2/m
Other Lepidocrocite Information
References:
NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic3)
See Also:
Links to other databases for Lepidocrocite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - GeoScienceWorld
8 - Google Images
9 - Google Scholar
10 - Handbook of Mineralogy (MinSocAm)
11 - Handbook of Mineralogy (UofA)
12 - HyperPhysics
13 - MinDAT
14 - Mineralienatlas (Deutsch)
15 - Online Mineral Museum
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - WWW-MINCRYST
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Lepidocrocite
FeO(OH)
Dana No: 06.01.02.02 Strunz No: 04.FE.15
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