Mongolite
A valid IMA mineral species
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About Mongolite
Formula:
Ca4Nb6Si5O24(OH)10 · nH2O
Colour:
Pale lilac or grayish lilac
Lustre:
Silky
Hardness:
2
Specific Gravity:
3.147
Crystal System:
Tetragonal
Name:
Named after the country of origin.
This page provides mineralogical data about Mongolite.
Unique Identifiers
Mindat ID:
2756
Long-form identifier:
mindat:1:1:2756:0
Similar Names
| Congolite | A valid IMA mineral species | Fe32+B7O13Cl |
| Monrolite | A synonym of Sillimanite |
IMA Classification of Mongolite
Approved
IMA Formula:
Ca4Nb5+6Si5O24(OH)10·6H2O
Approval year:
1983
First published:
1985
Classification of Mongolite
9.HF.05
9 : SILICATES (Germanates)
H : Unclassified silicates
F : With Nb, Ta, Zr
9 : SILICATES (Germanates)
H : Unclassified silicates
F : With Nb, Ta, Zr
56.2.4.15
56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
2 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or >[4] coordination
56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
2 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or >[4] coordination
17.8.5
17 : Silicates Containing other Anions
8 : Silicates with niobate or tantalate
17 : Silicates Containing other Anions
8 : Silicates with niobate or tantalate
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 |
|---|---|---|
| Mgl | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Mongolite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Mongolite
Silky
Transparency:
Translucent
Colour:
Pale lilac or grayish lilac
Hardness:
2 on Mohs scale
Cleavage:
Distinct/Good
One direction, good
One direction, good
Density:
3.147 g/cm3 (Measured) 3.53 g/cm3 (Calculated)
Optical Data of Mongolite
Type:
Uniaxial (-)
RI values:
nω = 1.80 nε = 1.74
Max. Birefringence:
δ = 0.060
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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Mongolite
Mindat Formula:
Ca4Nb6Si5O24(OH)10 · nH2O
Element Weights:
Common Impurities:
Ti,Al,Mn,Zn,Mg,Sr,Ba,Na,K
Crystallography of Mongolite
Crystal System:
Tetragonal
Cell Parameters:
a = 7.00(5) Å, c = 29.0(1) Å
Ratio:
a:c = 1 : 4.143
Unit Cell V:
1,421.00 ų (Calculated from Unit Cell)
Z:
2
Comment:
Point Group: n.d.; Space Group: n.d.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.163 Å | (100) |
| 2.974 Å | (70) |
| 3.087 Å | (65) |
| 9.67 Å | (45) |
| 5.82 Å | (45) |
| 2.664 Å | (40) |
| 2.901 Å | (35) |
Comments:
Dorozhnyi pegmatite, Mongolia. Data from type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Type Occurrence of Mongolite
General Appearance of Type Material:
Mica-like aggregate of fine scales.
Place of Conservation of Type Material:
A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia.
Geological Setting of Type Material:
A late alteration product of an unknown niobium silicate, in the quartz-rich core zone of an alkalic pegmatite.
Associated Minerals at Type Locality:
Synonyms of Mongolite
Other Language Names for Mongolite
Common Associates
Associations Based on Photo Data:
| 7 photos of Mongolite associated with Quartz | SiO2 |
| 5 photos of Mongolite associated with 'Kovalenkoite' | (K,Sr,Ba)2Ca5Nb12[Si8O52(O,OH)] · 15H2O |
| 1 photo of Mongolite associated with Arfvedsonite | NaNa2(Fe2+4Fe3+)Si8O22(OH)2 |
Related Minerals - Strunz-mindat Grouping
| 9.HF.10 | Loudounite | NaCa5Zr4Si16O40(OH)11 · 8H2O |
Other Information
Thermal Behaviour:
The DTA curve shows a broad endothermic effect between 100 and 350°C, (loss of water), and an exothermic effect at 700°C. The mineral does not melt below 1100°C.
Notes:
The mineral is insoluble in acid except HF.
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 Mongolite
mindat.org URL:
https://www.mindat.org/min-2756.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
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References for Mongolite
Reference List:
Localities for Mongolite
Showing 5 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.
Mongolia | |
| Vladykin (ed.) +7 other references |
| Zapiski Vserossiyskogo Mineralogicheskogo Obshchestva (Proceedings of the Russian Mineralogical Society) |
Russia | |
| Makagonov et al. (2017) |
| Pekov et al. (2004) |
| Sorokhtina et al. (2018) |
Quick NavTopAbout MongoliteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPronunciation Physical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Dorozhnyi pegmatite, Khan Bogd Peralkaline Granite, Khanbogd District, Ömnögovi Province, Mongolia