Feitknechtite (original) (raw)
A valid IMA mineral species
About FeitknechtiteHide
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Colour:
Lead-gray, brownish black
Lustre:
Resinous, Sub-Metallic, Dull, Earthy
Specific Gravity:
3.249 (Calculated)
Name:
Named in 1965 by Owen P. Brickner in honor of Walter Feitknecht [December 14, 1899 Schüpfen, Switzerland - 1975 Bern, Switzerland], systematic researcher relating to manganese oxide minerals and professor of Chemistry, University of Bern, Bern, Switzerland and who first synthesized the compound.
Black replacement of pyrochroite that yielded a mixture of hausmannite and feitknechtite. A specimen of black pyrochroite from the type locality was submitted to the RRUFF Project for Raman spectroscopic examination. Pyrochroite was detected, but not hausmannite or feitknechtite (Heixong Yang, personal communication, 2015).
The structure for a second, and perhaps novel, MnOOH polymorph (proposed designation ε-MnOOH), mixed with the synthetic feitknechtite, that is similar to β-MnOOH but with a different layer stacking.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:1473:7
261dc517-359c-4c41-9ee6-72b81b36c7ca
IMA Classification of FeitknechtiteHide
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Type description reference:
Classification of FeitknechtiteHide
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4.FE.25
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
6.1.4.3
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
7.18.6
7 : Oxides and Hydroxides
18 : Oxides of Mn
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Fkn | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Fkn | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of FeitknechtiteHide
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Resinous, Sub-Metallic, Dull, Earthy
Colour:
Lead-gray, brownish black
Density:
3.249 g/cm3 (Calculated)
Comment:
ICDD lists D (measured and calculated) = 3.80. Could be an error
Optical Data of FeitknechtiteHide
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RI values:
_n_ω = 2.055 _n_ε = 1.950
δ = 0.105
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Chemistry of FeitknechtiteHide
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Crystallography of FeitknechtiteHide
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Class (H-M):
3_m_ _(_32/m ) - Hexagonal Scalenohedral
Cell Parameters:
a = 3.32 Å, c = 4.71 Å
Unit Cell V:
44.96 ų (Calculated from Unit Cell)
Morphology:
Hexagonal platelets; granular, earthy.
Comment:
Space group for synthetic material. Note: the structure of another synthetic material (Post et al. 2023) is monoclinic, space group C2/m, a=5.6541(4), b=2.89075(2), c=4.8347(3) Å, β=108.0709(1) deg.
X-Ray Powder DiffractionHide
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Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.62 Å | (100) |
| 2.635 Å | (50) |
| 2.360 Å | (20b) |
| 1.960 Å | (10b) |
| 1.550 Å | (1) |
| 1.500 Å | (1) |
Comments:
ICDD 18-804 synthetic. Original data by Bricker (1965), but originally thought to be tetragonal.
Geological EnvironmentHide
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Type Occurrence of FeitknechtiteHide
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General Appearance of Type Material:
Black replacement of pyrochroite. May show trigonal platy appearance.
Geological Setting of Type Material:
Gossan zone of a manganiferous marble-hosted
Associated Minerals at Type Locality:
Reference:
Bricker, O. (1965) Some stability relations in the system Mn−O
2
−H
2
O at 25◦ and one atmosphere total pressure. American Mineralogist: 50: 1296–1354.
Other Language Names for FeitknechtiteHide
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Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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Fluorescence of FeitknechtiteHide
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Not fluorescent in ultraviolet
Other InformationHide
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Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for FeitknechtiteHide
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References for FeitknechtiteHide
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Reference List:
Localities for FeitknechtiteHide
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This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the 
symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Locality ListHide
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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. 
- Good crystals or important locality for species. 
- World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.