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Lepidocrocite

Big Photo

Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany
© Stephan Wolfsried

Show Lepidocrocite Photos (44)
Formula:
γ-Fe
3+
 
O(OH)
System:OrthorhombicColour:Deep red, red-brown
Lustre:Sub-MetallicHardness:5
Name:From the Greek λεπίς, scale, and κροκη, thread, in allusion to the occasional palmate or plumose aggregates.


Dimorphous with Goethite.

May be a component of limonite.

Classification of Lepidocrocite

IMA status:Approved
Strunz 8th edition ID:4/F.06-40
Nickel-Strunz 10th (pending) edition ID:4.FE.15

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
Dana 8th edition ID:6.1.2.2

6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
Hey's CIM Ref.:7.20.8

7 : Oxides and Hydroxides
20 : Oxides of Fe
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Type Occurrence of Lepidocrocite

Type Locality:Zlaté Hory (Zuckmantel), Olomouc Region, Moravia (Mähren; Maehren), Czech Republic
Year of Discovery:1813

Physical Properties of Lepidocrocite

Lustre:Sub-Metallic
Diaphaneity (Transparency):Transparent
Colour:Deep red, red-brown
Streak:Orange
Hardness (Mohs):5
Tenacity:Brittle
Cleavage:Perfect
{010}; {100} less perfect; {001} good.
Density (measured):4.05 - 4.13 g/cm3
Density (calculated):3.96 g/cm3

Crystallography of Lepidocrocite

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:a = 3.88Å, b = 12.54Å, c = 3.07Å
Ratio:a:b:c = 0.309 : 1 : 0.245
Unit Cell Volume:V 149.37 ų (Calculated from Unit Cell)
Morphology:Flattened scales {010} and slightly elongated [100]. {010} sometimes striated [100]. Single crystals attached by an edge to matrix; aggregated into palmate or plumose groups. Loose rosettes; massive, bladed to fibrous or micaceous. Fibrous varieties elongated [100].
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction:
d-spacingIntensity
6.26 (100)
3.29 (90)
2.47 (80)
1.937 (70)
1.732 (40)
1.524 (40)

Optical Data of Lepidocrocite

Type:Biaxial (-)
RI values: nα = 1.940 nβ = 2.200 nγ = 2.510
2V:Measured: 83° , Calculated: 84°
Maximum Birefringence:δ = 0.570

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Very High
Type:Anisotropic
Anisotropism:Strong
Dispersion:relatively weak
Colour in reflected light:Gray-white
Pleochroism:Strong
Comments:X = b = clear yellow
Y = c = dark red-orange
Z = a = darker red-orange

Chemical Properties of Lepidocrocite

Formula:
γ-Fe
3+
 
O(OH)
Essential elements:Fe, H, O
All elements listed in formula:Fe, H, O
Common Impurities:Mn

Relationship of Lepidocrocite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
4.FE.05Amakinite
(Fe
2+
 
,Mg)(OH)
 
2
4.FE.05Brucite
Mg(OH)
 
2
4.FE.05Portlandite
Ca(OH)
 
2
4.FE.05Pyrochroite
Mn(OH)
 
2
4.FE.05Theophrastite
Ni(OH)
 
2
4.FE.10Bayerite
Al(OH)
 
3
4.FE.10Doyleite
Al(OH)
 
3
4.FE.10Gibbsite
Al(OH)
 
3
4.FE.10Nordstrandite
Al(OH)
 
3
4.FE.15Böhmite
AlO(OH)
4.FE.20Grimaldiite
CrO(OH)
4.FE.20Heterogenite
CoO(OH)
4.FE.25Feitknechtite
Mn
3+
 
O(OH)
4.FE.25Lithiophorite
(Al,Li)MnO
 
2
(OH)
 
2
4.FE.30Quenselite
PbMnO
 
2
(OH)
4.FE.35Ferrihydrite
Fe
 
5
O
 
3
(OH)
 
9
4.FE.40Feroxyhyte
Fe
3+
 
O(OH)
4.FE.40Vernadite
(Mn
4+
 
,Fe
3+
 
,Ca,Na)(O,OH)
 
2
 · nH
 
2
O
4.FE.45Quetzalcoatlite
Zn
 
6
Cu
 
3
(TeO
 
6
)
 
2
(OH)
 
6
·Ag
 
x
Pb
 
y
Cl
 
x+2y
Related Minerals - Hey's Index Grouping:

- +
7.20.1Wüstite
FeO
7.20.2Magnetite
Fe
2+
 
Fe
3+
2
O
 
4
7.20.3Maghemite
Fe
 
2
O
 
3
7.20.4Hematite
Fe
 
2
O
 
3
7.20.5Goethite
α-Fe
3+
 
O(OH)
7.20.6Akaganeite
β-Fe
3+
 
O(OH,Cl)
7.20.7Feroxyhyte
Fe
3+
 
O(OH)
7.20.9Ferrihydrite
Fe
 
5
O
 
3
(OH)
 
9
7.20.10Amakinite
(Fe
2+
 
,Mg)(OH)
 
2
7.20.11Magnesioferrite
MgFe
3+
2
O
 
4
7.20.12Muskoxite
Mg
 
7
Fe
 
4
O
 
13
·10H
 
2
O
7.20.13Srebrodolskite
Ca
 
2
Fe
 
2
O
 
5
7.20.14Hercynite
FeAl
 
2
O
 
4
7.20.15Brownmillerite
Ca
 
2
(Al,Fe
3+
 
)
 
2
O
 
5

Other Names for Lepidocrocite

Synonyms:
Pyrrhosiderite
Other Languages:
Czech:Lepidokrokit
French:Lépidocrocite
German:Lepidokrokit
Göthit (of Lenz)
Lepidocrocit
Pyrrhosiderit
Rubinglimmer
Italian:Lepidocrocite
Japanese:鱗鉄鉱
Polish:Lepidokrokit
Russian:Лепидокрокит
Slovak:Lepidokrokit
Spanish:Lepidocrocita
Pyrrhosiderita
Varieties:
Hydrolepidocrocite

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Lepidocrocite

Reference List:Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 642-645.

Acta Chemica Scandinavica (1978): A: 87.

Internet Links for Lepidocrocite

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    Localities for Lepidocrocite

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