General Lepidocrocite Information
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Chemical Formula: |
FeO(OH) |
Composition: |
Molecular Weight = 88.85 gm |
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Iron 62.85 % Fe 89.86 % Fe2O3 |
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Hydrogen 1.13 % H 10.14 % H2O |
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Oxygen 36.01 % O |
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______ ______ |
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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." |
Synonym: |
Esmeraldaite |
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Esmeraldite |
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Hydrohematite |
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ICSD 27846 |
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PDF Aug-98 |
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Lepidocrocite Image |
Images:
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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 |
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Lepidocrocite Crystallography
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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 - DipyramidalH-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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Forms:
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Crystal Structure:
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Wyckoff R W G , Crystal Structures , 1 (1963) p.290-295, Second edition. Interscience Publishers, New York, New York
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Physical Properties of Lepidocrocite
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Cleavage: |
[010] Perfect |
Color: |
Red, Yellowish brown, Blackish brown. |
Density: |
4 |
Diaphaniety: |
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: |
None. |
Luster: |
Sub Metallic |
Streak: |
dark yellow brown |
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Optical Properties of Lepidocrocite
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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 |
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 |
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∑ R1(λ) |
∑ R2(λ) |
| 400 nm |
13.00 |
21.40 |

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| 420 nm |
12.70 |
20.30 |

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| 440 nm |
12.40 |
19.20 |

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| 460 nm |
12.00 |
18.60 |

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| 480 nm |
11.70 |
18.10 |

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| 500 nm |
11.40 |
17.80 |

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| 520 nm |
11.20 |
17.40 |

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| 540 nm |
11.00 |
17.00 |

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| 560 nm |
10.80 |
16.50 |

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| 580 nm |
10.70 |
16.00 |

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| 600 nm |
10.60 |
15.70 |

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| 620 nm |
10.50 |
15.40 |

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| 640 nm |
10.40 |
15.20 |

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| 660 nm |
10.40 |
15.10 |

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| 680 nm |
10.40 |
15.00 |

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| 700 nm |
10.40 |
14.90 |

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Calculated Relative Intensity Colors of Lepidocrocite in Air
Relative Intensity |
0% |
90% |
100% |
180% |
270% |
360% |
450% |
540% |
630% |
720% |
810% |
820% |
| R1 |
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| R2 |
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Calculated Properties of Lepidocrocite
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Electron Density: |
relectron=3.87 gm/cc note: rLepidocrocite =4.00 gm/cc. |
Fermion Index |
Fermion Index = 0.01349 Boson Index = 0.98651 |
Photoelectric: |
PELepidocrocite = 18.93 barns/electron U=PELepidocrocite x relectron= 73.29 barns/cc. |
Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Lepidocrocite is Not Radioactive |
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Lepidocrocite Classification
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Dana Class: |
6.1.2.2 (6)Hydroxides and Oxides Containing Hydroxyl |
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(6.1)where X+++O OH |
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(6.1.2)Dana Group |
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6.1.2.1 Boehmite AlO(OH) Amam 2/m 2/m 2/m |
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6.1.2.2 Lepidocrocite FeO(OH) Amam 2/m 2/m 2/m |
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6.1.2.3 Guyanaite CrO(OH) Pnnm 2/m 2/m 2/m |
Strunz Class: |
IV/F.06-40 IV - Oxides |
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IV/F - Hydroxides and oxidic hydrates, water-bearing oxides with layered structure |
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IV/F.06 - Diaspore - Goethite - Faitknechtite series |
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IV/F.06-10 Diaspore AlO(OH) Pbnm 2/m 2/m 2/m |
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IV/F.06-20 Boehmite AlO(OH) Amam 2/m 2/m 2/m |
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IV/F.06-25 Tsumgallite! GaO(OH) Pbnm 2/m 2/m 2/m |
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IV/F.06-30 Goethite FeO(OH) Pbnm 2/m 2/m 2/m |
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IV/F.06-40 Lepidocrocite FeO(OH) Amam 2/m 2/m 2/m |
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IV/F.06-50 Akaganeite Fe(O,OH,Cl) I2/m 2/m |
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IV/F.06-60 Feroxyhyte FeO(OH) Unk Hex |
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IV/F.06-70 Manganite MnO(OH) B21/d 2/m |
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IV/F.06-80 Groutite MnO(OH) Pbnm 2/m 2/m 2/m |
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IV/F.06-90 Feitknechtite beta-MnO(OH) Unk Hex |
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Other Lepidocrocite Information
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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 - Applied Mineralogy
5 -Athena
6 - Crocoite.com Mineral Locations
7 - EUROmin Project
8 -Google Images
9 -Google Scholar
10 -Handbook of Mineralogy (UofA)
11 - HyperPhysics
12 -MinDAT
13 -MinMax(Deutsch)
14 -MinMax(English)
15 -Mineralienatlas (Deutsch)
16 -QUT Mineral Atlas
17 - WWW-MINCRYST
18 -École des Mines de Paris
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Lepidocrocite
FeO(OH)
Dana No: 6.1.2.2 Strunz No: IV/F.06-40
Locality:
Notes:
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