Pseudosinhalite
A valid IMA mineral species
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About Pseudosinhalite
Formula:
Mg2Al3(BO3)2(OH)O3
Colour:
Colourless
Lustre:
Vitreous
Specific Gravity:
3.508 (Calculated)
Crystal System:
Monoclinic
Name:
The name alludes to the optical, chemical, and structural similarity to sinhalite.
Type Locality:
This page provides mineralogical data about Pseudosinhalite.
Unique Identifiers
Mindat ID:
7257
Long-form identifier:
mindat:1:1:7257:7
IMA Classification of Pseudosinhalite
Classification of Pseudosinhalite
6.AC.10
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
6 : BORATES
A : Monoborates
C : B(O,OH)4, without and with additional anions; 1(T), 1(T)+OH, etc
Mineral Symbols
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.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Pshl | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Pss | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Pseudosinhalite
Vitreous
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Cleavage:
None Observed
Parting:
None observed
Fracture:
Conchoidal
Density:
3.508 g/cm3 (Calculated)
Optical Data of Pseudosinhalite
Type:
Biaxial (-)
RI values:
nα = 1.691 nβ = 1.713 nγ = 1.73
Max. Birefringence:
δ = 0.039
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.
No measured or calculated 2V is on file for this mineral, so the value used here (82°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
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.
No measured or calculated 2V is on file for this mineral, so the value used here (82°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
r > v or r < v
Chemistry of Pseudosinhalite
Mindat Formula:
Mg2Al3(BO3)2(OH)O3
Element Weights:
Crystallography of Pseudosinhalite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/c
Cell Parameters:
a = 7.49(1) Å, b = 4.33(1) Å, c = 9.85(1) Å
β = 110.7(1)°
β = 110.7(1)°
Ratio:
a:b:c = 1.73 : 1 : 2.275
Unit Cell V:
298.83 ų (Calculated from Unit Cell)
Z:
2
Twinning:
Polysynthetic.
Comment:
Space group by analogy to synthetic material.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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) |
|---|---|---|---|---|---|---|---|
| 0012323 | Pseudosinhalite | Daniels P, Krosse S, Werding G, Schreyer W (1997) "Pseudosinhalite", a new hydrous MgAl-borate: synthesis, phase characterization, crystal structure, and PT-stability Contributions to Mineralogy and Petrology 128 261-271 | 1997 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.14 Å | (100) |
| 1.625 Å | (100) |
| 2.102 Å | (60) |
| 3.21 Å | (40) |
| 2.61 Å | (40) |
| 1.607 Å | (40) |
| 1.399 Å | (40) |
Comments:
Tayezhnoe Fe-B skarn, Russia. The data are from Schreyer et al. (1998).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) |
Type Occurrence of Pseudosinhalite
Place of Conservation of Type Material:
Institut für Mineralogie, Ruhr-Universität Bochum, Germany.
Geological Setting of Type Material:
As a replacement product of sinhalite, in an impure marble at the contact of a metasomatic iron boron deposit.
Associated Minerals at Type Locality:
Synonyms of Pseudosinhalite
Other Language Names for Pseudosinhalite
Common Associates
Associations Based on Photo Data:
| 7 photos of Pseudosinhalite associated with Spinel | MgAl2O4 |
| 4 photos of Pseudosinhalite associated with Geikielite | MgTiO3 |
| 2 photos of Pseudosinhalite associated with Magnesiotaaffeite-6N’3S | Mg2BeAl6O12 |
Related Minerals - Strunz-mindat Grouping
| 6.AC.05 | Sinhalite | MgAl(BO4) |
| 6.AC.15 | Béhierite | Ta(BO4) |
| 6.AC.15 | Schiavinatoite | Nb(BO4) |
| 6.AC.20 | Frolovite | Ca[B(OH)4]2 |
| 6.AC.25 | Hexahydroborite | Ca[B(OH)4]2 · 2H2O or CaB2O4 · 6H2O |
| 6.AC.30 | Henmilite | Ca2Cu[B(OH)4]2(OH)4 |
| 6.AC.35 | Bandylite | Cu[B(OH)4]Cl |
| 6.AC.40 | Teepleite | Na2[B(OH)4]Cl |
| 6.AC.45 | Moydite-(Y) | Y[B(OH)4](CO3) |
| 6.AC.50 | Carboborite | Ca2Mg[B(OH)4]2(CO3)2 · 4H2O |
| 6.AC.55 | Sulfoborite | Mg3[B(OH)4]2(SO4)(OH,F)2 |
| 6.AC.60 | Lüneburgite | Mg3[B2(OH)6](PO4)2 · 6H2O |
| 6.AC.65 | Seamanite | Mn2+3[B(OH)4](PO4)(OH)2 |
| 6.AC.70 | Cahnite | Ca2[B(OH)4](AsO4) |
Fluorescence of Pseudosinhalite
Not fluorescent.
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 Pseudosinhalite
mindat.org URL:
https://www.mindat.org/min-7257.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Pseudosinhalite
Reference List:
Daniels, Peter, Krosse, Sigrid, Werding, Günter, Schreyer, Werner (1997) "Pseudosinhalite", a new hydrous MgAl-borate: synthesis, phase characterization, crystal structure, and PT -stability. Contributions to Mineralogy and Petrology, 128 (2) 261-271 doi:10.1007/s004100050307
Localities for Pseudosinhalite
Showing 2 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.
Austria | |
| Bernhard et al. (2008) |
Russia (TL) | |
| Schreyer et al. (1998) +1 other reference |
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Stubenberg Quarry, Stubenberg am See, Hartberg-Fürstenfeld District, Styria, Austria