Lepidocrocite Mineral Data

General Lepidocrocite Information

Chemical Formula:

FeO(OH)

Composition:

Molecular Weight = 88.85 gm

Iron 62.85 % Fe 89.86 % Fe₂O₃

Hydrogen 1.13 % H 10.14 % H₂O

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

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 6.26(1), 3.29(0.9), 2.47(0.8),

Forms:

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Forms: ( 0 3 1) ( 2 0 1) ( 0 1 0) ( 4 0 1) ( 1 0 0) ( 0 0 1)

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Physical Properties of Lepidocrocite

Cleavage:

{010} Perfect

Color:

Red, Yellowish brown, Blackish brown.

Density:

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	R₂	∑ 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:

PE_{Lepidocrocite}= 18.93 barns/electron
U=PE_{Lepidocrocite} x rElectron 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
Locality:

Notes:

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