General Goethite Information
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Chemical Formula: |
Fe+++O(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) 1806 |
Locality: |
Mesabi district, Minnesota, USA. Link to MinDat.org Location Data. |
Name Origin: |
Named after the German poet, J. W. Goethe (1749-1832). |
Synonym: |
Acicular iron ore |
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ICSD 28247 |
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Limonite |
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Needle ironstone |
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PDF 29-713 |
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Goethite Image |
Images:
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Images:
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Goethite Laubmannite
Comments: Reddish brown goethite hosting radiating sprays of olive green laubmannite to 3 cm across.
Location: Buckeye Mountain, Polk County, Arkansas, USA.
Scale: 10.5 x 7.5 cm.
© John Veevaert |
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Goethite Crystallography
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Axial Ratios: |
a:b:c =0.4615:1:0.3034 |
Cell Dimensions: |
a = 4.596, b = 9.957, c = 3.021, Z = 4; V = 138.25 Den(Calc)= 4.27 |
Crystal System: |
Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pbnm |
X Ray Diffraction: |
By Intensity(I/Io): 4.18(1), 2.69(0.3), 2.452(0.25), |
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Crystal Structure:
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Gualtieri A , Venturelli P , American Mineralogist , 84 (1999) p.895-904, In situ study of the goethite-hematite phase transformation by real time, synchrotron powder diffraction, Sample at T = 25 C
View Additional jPOWD Structure files for Goethite
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[6]
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Physical Properties of Goethite
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Cleavage: |
[010] Perfect, [100] Distinct |
Color: |
Brown, Reddish brown, Yellowish brown, Brownish yellow, Ocher yellow. |
Density: |
3.3 - 4.3, Average = 3.8 |
Diaphaniety: |
Subtranslucent to opaque |
Fracture: |
Hackly - Jagged, torn surfaces, (e.g. fractured metals). |
Habit: |
Acicular - Occurs as needle-like crystals. |
Habit: |
Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite) |
Habit: |
Reniform - "Kidney like" in shape (e.g.. hematite). |
Hardness: |
5-5.5 - Apatite-Knife Blade |
Luminescence: |
None. |
Luster: |
Adamantine - Silky |
Streak: |
yellowish brown |
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Optical Properties of Goethite
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Gladstone-Dale: |
CI meas= -0.14 (Poor) - where the CI = (1-KPDmeas/KC) CI calc= -0.014 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.322,KPDmeas= 0.3618,KC= 0.3175 |
Optical Data: |
Biaxial (-), a=2.26-2.275, b=2.393-2.409, g=2.398-2.515, bire=0.1380-0.2400, 2V(Calc)=20-78, 2V(Meas)=0-27. Dispersion r > v extreme. |
Pleochroism (x): |
yellow or colorless. |
Pleochroism (y): |
brownish yellow or ocher yellow. |
Pleochroism (z): |
orangish yellow or deep reddish orange. |
RL Anisotrophism: |
Distinct in bluish grays. |
RL Color: |
Gray with bluish tint with yellow, red, brown internal reflections. |
Reflectivity |
Standardized Intensity (100%) Reflection Spectra of Goethite in Air
| λ |
R1 |
R2 |
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∑ R1(λ) |
∑ R2(λ) |
| 400 nm |
17.50 |
19.20 |

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| 420 nm |
16.70 |
18.30 |

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| 440 nm |
15.90 |
17.40 |

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| 460 nm |
15.20 |
16.70 |

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| 480 nm |
14.60 |
16.00 |

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| 500 nm |
14.10 |
15.50 |

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| 520 nm |
13.70 |
15.00 |

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| 540 nm |
13.30 |
14.60 |

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| 560 nm |
13.00 |
14.30 |

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| 580 nm |
12.80 |
14.00 |

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| 600 nm |
12.50 |
13.70 |

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| 620 nm |
12.40 |
13.50 |

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| 640 nm |
12.20 |
13.40 |

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| 660 nm |
12.00 |
13.20 |

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| 680 nm |
12.00 |
13.10 |

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| 700 nm |
11.90 |
13.00 |

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Calculated Relative Intensity Colors of Goethite in Air
Relative Intensity |
0% |
70% |
100% |
140% |
210% |
280% |
350% |
420% |
490% |
560% |
630% |
680% |
| R1 |
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| R2 |
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Calculated Properties of Goethite
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Electron Density: |
relectron=4.13 gm/cc note: rGoethite =4.27 gm/cc. |
Fermion Index |
Fermion Index = 0.01349 Boson Index = 0.98651 |
Photoelectric: |
PEGoethite = 18.93 barns/electron U=PEGoethite x relectron= 78.24 barns/cc. |
Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Goethite is Not Radioactive |
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Goethite Classification
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Dana Class: |
6.1.1.2 (6)Hydroxides and Oxides Containing Hydroxyl |
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(6.1)where X+++O OH |
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(6.1.1)Diaspore group (Orthorhombic, Pnma or Pnmd) |
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6.1.1.1 Diaspore AlO(OH) Pbnm 2/m 2/m 2/m |
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6.1.1.2 Goethite FeO(OH) Pbnm 2/m 2/m 2/m |
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6.1.1.3 Groutite MnO(OH) Pbnm 2/m 2/m 2/m |
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6.1.1.4 Montroseite (V,Fe,V)O(OH) Pbnm 2/m 2/m 2/m |
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6.1.1.5 Bracewellite CrO(OH) Pbnm 2/m 2/m 2/m |
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6.1.1.6 Tsumgallite! GaO(OH) Pbnm 2/m 2/m 2/m |
Strunz Class: |
IV/F.06-30 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 Goethite Information
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References: |
NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1) |
See Also: |
Links to other databases for Goethite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 -Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Applied Mineralogy
6 -Athena
7 - CalTech Mineral Spectroscopy
8 - Crocoite.com Mineral Locations
9 - EUROmin Project
10 - Franklin Minerals(Dunn)
11 - Franklin Minerals(Palache)
12 - Glendale Community College
13 -Google Images
14 -Google Scholar
15 -Handbook of Mineralogy (UofA)
16 - HyperPhysics
17 -MinDAT
18 -MinMax(Deutsch)
19 -MinMax(English)
20 -Mineralienatlas (Deutsch)
21 - Minerals of Wisconsin
22 -QUT Mineral Atlas
23 - Scandinavian mineral gallery
24 -University of Colorado - Mineral Structure Data
25 - University of Manchester - Mineral Structure
26 -University of Minnesota
27 - WWW-MINCRYST
28 -theimage
29 -École des Mines de Paris
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Print or Cut-and-Paste your Goethite Specimen Label here :
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Goethite
Fe+++O(OH)
Dana No: 6.1.1.2 Strunz No: IV/F.06-30
Locality:
Notes:
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