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Medenbachite
A valid IMA mineral species
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About Medenbachite
Olaf Medenbach
Formula:
Bi2Fe3+Cu2+(AsO4)2O(OH)3
Endmember formula; Cu may be replaced by minor Fe3+.
Colour:
Yellow to brown-yellow
Lustre:
Adamantine, Vitreous
Hardness:
4½
Specific Gravity:
5.90 (Calculated)
Crystal System:
Triclinic
Name:
Named by W. Krause, H.-J. Bernhardt, W. Gebert, H. Graetsch, K. Belendorff, and K. Petitjean in 1996 in honor of Olaf Medenbach (1949 – ), mineralogist, Ruhr University, Bochum, Germany. He has authored/coauthored descriptions of about 50 new minerals.
Unique Identifiers
Mindat ID:
2625
Long-form identifier:
mindat:1:1:2625:9
IMA Classification of Medenbachite
Approved
IMA Formula:
Bi3+2Fe3+Cu2+(As5+O4)2O(OH)3
Approval year:
1993
First published:
1996
Type description reference:
Classification of Medenbachite
8.BK.10
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
K : With medium-sized and large cations, (OH, etc.):RO4 = 2:1, 2.5:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
K : With medium-sized and large cations, (OH, etc.):RO4 = 2:1, 2.5:1
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Mdb | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Medenbachite
Adamantine, Vitreous
Transparency:
Transparent, Translucent
Colour:
Yellow to brown-yellow
Hardness:
4½ on Mohs scale
Hardness:
VHN25=420 kg/mm2 - Vickers
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
5.90 g/cm3 (Calculated)
Optical Data of Medenbachite
Type:
Biaxial (-)
RI values:
nα = 2.03 nβ = 2.09 nγ = 2.1
2V:
Measured: 43° , Calculated: 42°
Max. Birefringence:
δ = 0.070
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v
Chemistry of Medenbachite
Mindat Formula:
Bi2Fe3+Cu2+(AsO4)2O(OH)3
Endmember formula; Cu may be replaced by minor Fe3+.
Endmember formula; Cu may be replaced by minor Fe3+.
Element Weights:
Crystallography of Medenbachite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 4.57 Å, b = 6.162 Å, c = 8.993 Å
α = 94.56°, β = 99.69°, γ = 94.28°
α = 94.56°, β = 99.69°, γ = 94.28°
Ratio:
a:b:c = 0.742 : 1 : 1.459
Unit Cell V:
247.842 ų
Z:
1
Morphology:
The crystals are tabular on {-101} and slightly elongated parallel to [111]. They exhibit two main zones: One is parallel to [111] and includes {-101}, {-110},
{0-11}, and the other is parallel to [010] and includes {-101}, {101}, and {001}.
{0-11}, and the other is parallel to [010] and includes {-101}, {101}, and {001}.
Crystal Structure
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2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0002817 | Medenbachite | Krause W, Bernhardt H J, McCammon C A, Effenberger H (2002) Neustadtelite and cobaltneustadtelite, the Fe- and Co- analogues of medenbachite American Mineralogist 87 726-738 |  | 2002 | 0 | 293 | |
| 0001791 | Medenbachite | Krause W, Bernhardt H J, Gebert W, Graetsch H, Belendorff K, Petitjean K (1996) Medenbachite, Bi2Fe(Cu,Fe)(O,OH)2(OH)2(AsO4)2, a new mineral species: Its description and crystal structure American Mineralogist 81 505-512 | | 1996 | 0 | 293 | |
| 0001790 | Medenbachite | Krause W, Bernhardt H J, Gebert W, Graetsch H, Belendorff K, Petitjean K (1996) Medenbachite, Bi2Fe(Cu,Fe)(O,OH)2(OH)2(AsO4)2, a new mineral species: Its description and crystal structure American Mineralogist 81 505-512 | | 1996 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.82 Å | (60) |
| 5.26 Å | (40) |
| 3.749 Å | (100) |
| 3.596 Å | (80) |
| 3.468 Å | (60) |
| 2.903 Å | (70) |
| 2.685 Å | (50) |
| 2.558 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Medenbachite
General Appearance of Type Material:
Very small, intergrown, tabular crystals up to 0.2 mm in length, often forming aggregates of parallel intergrowths, which crystallize within cavernous quartz.
Place of Conservation of Type Material:
Institut fur Mineralogie, Ruhr-Universitiit Bochum, Germany
Geological Setting of Type Material:
Weathering of small ore impregnations in a silicified barite vein.
Associated Minerals at Type Locality:
Reference:
Synonyms of Medenbachite
Other Language Names for Medenbachite
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.BK.05 | Brazilianite | NaAl3(PO4)2(OH)4 |
| 8.BK.10 | Neustädtelite | Bi2Fe3+(Fe3+,Co)(AsO4)2(O,OH)4 |
| 8.BK.10 | Cobaltneustädtelite | Bi2Fe3+(Co,Fe3+)(AsO4)2(O,OH)4 |
| 8.BK.15 | Curetonite | Ba(Al,Ti)(PO4)(OH,O)F |
| 8.BK.20 | Heyite | Pb5Fe2+2(VO4)2O4 |
| 8.BK.25 | Jamesite | Pb2Zn(Fe2+,Zn)2Fe3+4(AsO4)4(OH)10 |
| 8.BK.25 | Lulzacite | Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10 |
| 8.BK.25 | Désorite | Pb2(Fe3+6Zn)O2(PO4)4(OH)8 |
| 8.BK.30 | Nishanbaevite | KAl2O(AsO4)(SO4) |
| 8.BK.35 | Zircarsite | Na18Cu12ZrO8(AsO4)8Cl6 |
| 8.BK.35 | Arsmirandite | Na18Cu12Fe3+O8(AsO4)8Cl5 |
| 8.BK.35 | Lebedevite | K4Na14Cu14O8(AsO4)8Cl6 |
| 8.BK.35 | Lehmannite | Na18Cu12TiO8(AsO4)8FCl5 |
Fluorescence of Medenbachite
None
Other Information
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 Medenbachite
mindat.org URL:
https://www.mindat.org/min-2625.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Medenbachite
Reference List:
Krause, Werner, Bernhardt, Heinz-Juergen, Gebert, Walter, Graetsch, Heribert, Belendorff, Klaus, Petitjean, Klaus (1996) Medenbachite, Bi2Fe(Cu,Fe)(O,OH)2(OH)2(AsO4)2, a new mineral species; its description and crystal structure. American Mineralogist, 81 (3) 505-512 doi:10.2138/am-1996-3-424
Localities for Medenbachite
Showing 6 localities.
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Germany | |
| Walenta (1996) |
| Walenta (1998) | |
| Krause (1996) |
| S Wolfsried collection |
Poland | |
| Siuda et al. (2003) |
Portugal | |
| Alves (n.d.) |
Point 8.0, Borstein, Reichenbach, Lautertal, Bergstraße, Darmstadt, Hesse, Germany