Davreuxite
A valid IMA mineral species - grandfathered
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About Davreuxite
Formula:
MnAl6Si4O17(OH)2
Colour:
Creamy-white, pale rose pink
Hardness:
2 - 3
Specific Gravity:
3.30 - 3.38
Crystal System:
Monoclinic
Name:
Originally reported and described by de Koninck in 1878. Named after Belgian pharmacist, natural scientist, and Professor of Mineralogy at the University of Liège Charles Joseph Davreux (Liège, Belgium 10th September 1800 - Liège, Belgium 11th April 1863).
Type Locality:
This page provides mineralogical data about Davreuxite.
Unique Identifiers
Mindat ID:
1237
Long-form identifier:
mindat:1:1:1237:5
IMA Classification of Davreuxite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mn2+Al6Si4O17(OH)2
Classification of Davreuxite
9.BF.15
9 : SILICATES (Germanates)
B : Sorosilicates
F : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in tetrahedral [4] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
F : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in tetrahedral [4] and greater coordination
58.1.2.1
58 : SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
1 : Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [4] and higher coordination; single and double groups (n=1, 2)
58 : SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
1 : Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [4] and higher coordination; single and double groups (n=1, 2)
16.16.3
16 : Silicates Containing Aluminum and other Metals
16 : Aluminosilicates of Mn
16 : Silicates Containing Aluminum and other Metals
16 : Aluminosilicates of Mn
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 |
|---|---|---|
| Drx | 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 Davreuxite
Transparency:
Transparent, Translucent
Colour:
Creamy-white, pale rose pink
Hardness:
2 - 3 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {100}.
Good on {100}.
Comment:
Cross fractures on {010}.
Density:
3.30 - 3.38 g/cm3 (Measured) 3.34 g/cm3 (Calculated)
Optical Data of Davreuxite
Type:
Biaxial (-)
RI values:
nα = 1.66 nβ = 1.684 nγ = 1.69
2V:
Measured: 48° , Calculated: 52°
Max. Birefringence:
δ = 0.030
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:
weak
Chemistry of Davreuxite
Mindat Formula:
MnAl6Si4O17(OH)2
Element Weights:
Common Impurities:
Ti,Fe,Cr,Cu,Zn,Mg,P
Crystallography of Davreuxite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Setting:
P21/m
Cell Parameters:
a = 9.55 Å, b = 5.77 Å, c = 12.88 Å
β = 116.82°
β = 116.82°
Ratio:
a:b:c = 1.655 : 1 : 2.232
Unit Cell V:
633.39 ų (Calculated from Unit Cell)
Z:
2
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 0000955 | Davreuxite | Sahl K, Jones P G, Sheldrick G M (1984) The crystal structure of davreuxite, MnAl6Si4O17(OH)2 American Mineralogist 69 783-787 |  | 1984 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.511 Å | (100) |
| 2.870 Å | (60) |
| 3.103 Å | (45) |
| 4.290 Å | (40) |
| 5.719 Å | (35) |
| 2.840 Å | (35) |
| 8.51 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Type Occurrence of Davreuxite
General Appearance of Type Material:
fibrous masses in quartz veins, in close association with pyrophyllite and kaolinite.
Place of Conservation of Type Material:
Royal Belgium Institute of Natural Sciences, Brussels
Mineralogical Museum University of Wroclaw, Poland
Mineralogical Museum University of Wroclaw, Poland
Associated Minerals at Type Locality:
Other Language Names for Davreuxite
Common Associates
Associations Based on Photo Data:
| 2 photos of Davreuxite associated with Quartz | SiO2 |
| 1 photo of Davreuxite associated with Chlorite Group |
Related Minerals - Strunz-mindat Grouping
| 9.BF.05 | Harstigite | Ca6(Mn,Mg)Be4Si6(O,OH)24 |
| 9.BF.10 | Samfowlerite | Ca28Mn6Zn4(Be,Zn)4Be12[(OH)3(SiO4)3(Si2O7)2]4 |
| 9.BF.20 | Queitite | Pb4Zn2(SO4)(SiO4)(Si2O7) |
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 Davreuxite
mindat.org URL:
https://www.mindat.org/min-1237.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Davreuxite
Reference List:
Fleischer, Michael; Pabst, Adolf, White, John Sampson (1978) New mineral names. American Mineralogist, 63 (7-8). 793-796 p.795
Fransolet, Andre-Mathieu, Abraham, Kurt, Sahl, Kurt (1984) Davreuxite: a reinvestigation. American Mineralogist, 69 (7-8) 777-782
Localities for Davreuxite
Showing 9 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.
Belgium | |
| Fransolet et al. (1984) +1 other reference |
| Michel Blondieau. +2 other references |
| H.J. Wilke collection | |
| de Koninck (1878) +7 other references | |
| Corin (1929) +2 other references | |
| Hatert et al. (2002) |
| Hatert et al. (2002) | |
| Blondieau (2005) | |
Germany | |
| Färber (n.d.) |
Quick NavTopAbout DavreuxiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Ottré, Bihain, Vielsalm, Luxembourg, Wallonia, Belgium