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Magnesiodumortierite
A valid IMA mineral species
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About Magnesiodumortierite
Formula:
Mg(Al2OH)(Al2O)2(SiO4)3(BO3)
The given formula is the simplified end-member. Additional hydrogen incorporation is possible (compensated by additional Mg replacement of Al in the Al2(O,OH) structural unit, and/or âť replacement of Mg; see dumortierite).
Colour:
Pink to red
Lustre:
Vitreous
Hardness:
7 - 8
Specific Gravity:
3.22 (Calculated)
Crystal System:
Orthorhombic
Member of:
Unique Identifiers
Mindat ID:
2473
Long-form identifier:
mindat:1:1:2473:6
IMA Classification of Magnesiodumortierite
Approved
IMA Formula:
MgAl6BSi3O17(OH)
Approval year:
1992
Classification of Magnesiodumortierite
9.AJ.10
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
54.1.2.2
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
1 : Borosilicates and Some Beryllosilicates with (BO3)
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
1 : Borosilicates and Some Beryllosilicates with (BO3)
Mineral Symbols
As of 2021 there are now IMAâCNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Mdum | IMAâCNMNC | Warr, L.N. (2021). IMAâCNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Magnesiodumortierite
Vitreous
Colour:
Pink to red
Streak:
White
Hardness:
7 - 8 on Mohs scale
Cleavage:
Poor/Indistinct
very poor cleavage plane, parallel to [001]
very poor cleavage plane, parallel to [001]
Density:
3.22 g/cm3 (Calculated)
Optical Data of Magnesiodumortierite
Type:
Biaxial (-)
RI values:
nα = 1.678(1) nβ = 1.700 nγ = 1.701(1)
2V:
Measured: 38° (1), Calculated: 24°
Max. Birefringence:
δ = 0.023
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 Âľm 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 Âľm 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 strong
Pleochroism:
Weak
Comments:
X pale pink to red, Y and Z colourless;
Chemistry of Magnesiodumortierite
Mindat Formula:
Mg(Al2OH)(Al2O)2(SiO4)3(BO3)
The given formula is the simplified end-member. Additional hydrogen incorporation is possible (compensated by additional Mg replacement of Al in the Al2(O,OH) structural unit, and/or âť replacement of Mg; see dumortierite).
The given formula is the simplified end-member. Additional hydrogen incorporation is possible (compensated by additional Mg replacement of Al in the Al2(O,OH) structural unit, and/or âť replacement of Mg; see dumortierite).
Element Weights:
Common Impurities:
Ti,Fe,P
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| SiO2 | 31.37 % |
| P2O5 | 0.03 % |
| TiO2 | 3.93 % |
| Al2O3 | 46.83 % |
| FeO | 0.12 % |
| MnO | 0.03 % |
| MgO | 8.69 % |
| CaO | 0.01 % |
| B2O3 | 6.06 % |
| Total: | 97.07 % |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Case Ramello, Case Parigi, Martiniana Po, Cuneo Province, Piedmont, Italy | The analysis is published before magnesiodumortierite was published and the analysis was published as "dumortierite" by Schertl et al. (1991). The chemical composition of this sample however corresponds with magnesiodumortierite. The analysis is taken from an inclusion in a pyrope megacryst from a coesite-phengite-pyrope whiteschist. |
Crystallography of Magnesiodumortierite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 11.91(3) Å, b = 20.40(3) Å, c = 4.730(2) Å
Ratio:
a:b:c = 0.584 : 1 : 0.232
Unit Cell V:
1,149.22 Ă
Âł (Calculated from Unit Cell)
Z:
4
Comment:
Space Group: Pmcn
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0006582 | Magnesiodumortierite | Ferraris G, Ivaldi G, Chopin C (1995) Magnesiodumortierite, a new mineral from very-high-pressure rocks (Western Alps). Part I: Crystal structure European Journal of Mineralogy 7 167-174 | 1995 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.89 Ă | (90) |
| 5.84 Ă | (90) |
| 5.09 Ă | (90) |
| 3.87 Ă | (50) |
| 3.827 Ă | (50) |
| 3.450 Ă | (75) |
| 3.227 Ă | (85) |
| 2.926 Ă | (90) |
| 2.546 Ă | (100) |
| 2.100 Ă | (55) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Magnesiodumortierite
Co-Type Localities:
Place of Conservation of Type Material:
Museum national d'Histoire naturelle (Paris) and the Museo Regionale di Scienze Naturali (Torino, no. 93005.1/2).
Geological Setting of Type Material:
inclusions in pyrope megablasts of the coesite-bearing "whiteschists"
Associated Minerals at Type Locality:
Synonyms of Magnesiodumortierite
Other Language Names for Magnesiodumortierite
Relationship of Magnesiodumortierite to other Species
Member of:
Other Members of Dumortierite Group:
| Dumortierite | Al(Al2O)(Al2O)2(SiO4)3(BO3) | Orth. mmm(2/m2/m2/m) |
Common Associates
Associations Based on Photo Data:
| 5 photos of Magnesiodumortierite associated with Kyanite | Al2(SiO4)O |
| 5 photos of Magnesiodumortierite associated with Cordierite | Mg2Al4Si5O18 |
| 5 photos of Magnesiodumortierite associated with Talc | Mg3Si4O10(OH)2 |
| 3 photos of Magnesiodumortierite associated with Quartz | SiO2 |
| 1 photo of Magnesiodumortierite associated with Rutile | TiO2 |
Related Minerals - Strunz-mindat Grouping
| 9.AJ. | Hingganite-(Nd) | Nd2âťBe2Si2O8(OH)2 |
| 9.AJ. | Arrheniusite-(Ce) | CaMg[(Ce7Y3)Ca5](SiO4)4(Si2B3AsO18)(BO3)F11 |
| 9.AJ.05 | Ominelite | (Fe2+,Mg)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.05 | Grandidierite | (Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.10 | Dumortierite | Al(Al2O)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.10 | Nioboholtite | (Nb0.6âť0.4)Al6BSi3O18 |
| 9.AJ.10 | Titanoholtite | (Ti0.75âť0.25)Al6BSi3O18 |
| 9.AJ.10 | Holtite | (Ta0.6âť0.4)Al6BSi3O18(O,OH)2.25 |
| 9.AJ.15 | Garrelsite | Ba3NaSi2B7O16(OH)4 |
| 9.AJ.20 | 'Muromontite' | near Be2FeY2Si3O12 |
| 9.AJ.20 | Gadolinite-(Nd) | Nd2Fe2+Be2O2(SiO4)2 |
| 9.AJ.20 | Datolite | CaB(SiO4)(OH) |
| 9.AJ.20 | Melanocerite-(Ce) | (Ce,Ca)5(SiO4,BO4)3(OH,O) |
| 9.AJ.20 | Gadolinite-(Ce) | (Ce,La,Nd,Y)2Fe2+Be2Si2O10 |
| 9.AJ.20 | Gadolinite-(Y) | Y2Fe2+Be2Si2O10 |
| 9.AJ.20 | 'Unnamed (OH-analogue of Gadolinite-(Y))' | (Y,Ca)2(Fe,âť)Be2Si2O8(OH,O)2 |
| 9.AJ.20 | Hingganite-(Ce) | (Ce,REE)2(âť,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Y) | (Y,REE,Ca)2(âť,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Yb) | (Yb,Y,REE)2âťBe2[SiO4]2(OH)2 |
| 9.AJ.20 | Homilite | Ca2(Fe2+,Mg)B2Si2O10 |
| 9.AJ.20 | 'Minasgeraisite-(Y)' | (Ca2Y2)âť2(Be2B2)[SiO4]4(OH)4 |
| 9.AJ.20 | Calcybeborosilite-(Y) | (Y,Ca)2(âť,Fe2+)(B,Be)2[SiO4]2(OH,O)2 |
| 9.AJ.25 | Stillwellite-(La) | LaBSiO5 |
| 9.AJ.25 | Stillwellite-(Ce) | (Ce,La,Ca)BSiO5 |
| 9.AJ.30 | Cappelenite-(Y) | Ba(Y,Ce)6Si3B6O24F2 |
| 9.AJ.35 | Laptevite-(Ce) | Ca6(Fe2+,Mn2+)Y3REE7(SiO4)3(PO4)(B3Si3O18)(BO3)F11 |
| 9.AJ.35 | Proshchenkoite-(Y) | Ca(Y,REE,Ca,Na,Mn)15Fe2+(P,Si)Si6B3O34F14 |
| 9.AJ.35 | Okanoganite-(Y) | (Na,Ca)3(Y,Ce)12Si6B2O27F14 |
| 9.AJ.35 | Hundholmenite-(Y) | (Y,REE,Ca,Na)15(Al,Fe3+)(CaxAs3+1-x)(Si,As5+)Si6B3(O,F)48 |
| 9.AJ.35 | Vicanite-(Ce) | (Ca,Ce,La,Th)15As5+(As3+0.5,Na0.5)Fe3+Si6B4O40F7 |
| 9.AJ.40 | Jadarite | LiNaSiB3O7(OH) |
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 Magnesiodumortierite
mindat.org URL:
https://www.mindat.org/min-2473.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Magnesiodumortierite
Reference List:
Ferraris, Giovanni, Ivaldi, Gabriella, Chopin, Christian (1995) Magnesiodumortierite, a new mineral from very-high-pressure rocks (Western Alps) Part I: Crystal structure. European Journal of Mineralogy, 7 (1) 167-174 doi:10.1127/ejm/7/1/0167
Chopin, Christian, Ferraris, Giovanni, Ivaldi, Gabriella, Schertl, Hans-Peter, Schreyer, Werner, Compagnoni, Roberto, Davidson, Cameron, Davis, Andrew M. (1995) Magnesiodumortierite, a new mineral from very-high-pressure rocks (western Alps) II. Crystal chemistry and petrological significance. European Journal of Mineralogy, 7 (3) 525-536 doi:10.1127/ejm/7/3/0525
Ferraris, Giovanni, Ivaldi, Gabriella, Chopin, Christian (1995) Magnesiodumortierite, a new mineral from very-high-pressure rocks (Western Alps) Part I: Crystal structure. European Journal of Mineralogy, 7 (1) 167-174 doi:10.1127/ejm/7/1/0167
Evans, R. J., Groat, L. A. (2012) Structure and topology of dumortierite and dumortierite-like materials. The Canadian Mineralogist, 50 (5) 1197-1231 doi:10.3749/canmin.50.5.1197
Wunder, Bernd, Kutzschbach, Martin, Hosse, Luisa, Wilke, Franziska D.H., Schertl, Hans-Peter, Chopin, Christian (2018) Synthetic [4]B-bearing dumortierite and natural [4]B-free magnesiodumortierite from the Dora-Maira Massif: differences in boron coordination in response to ultrahigh pressure. European Journal of Mineralogy, 30 (3) 471-483 doi:10.1127/ejm/2018/0030-2742
Localities for Magnesiodumortierite
Showing 10 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
â - 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.
Italy (TL) | |
| Chopin et al. (1995) |
| Chopin et al. (1995) +1 other reference | |
| Piccoli et al. (2007) |
| Chopin et al. (1995) |
| Beppe Finello find and collection |
Norway | |
| Visser et al. (1991) |
| Jan Kihle specimen |
| Kihle (2013) | |
| Grew et al. (1996) |
| Jan Kihle photos & identification. |
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Magnesiodumortierite occurrence, Kragerø, Telemark, Norway