Ussingite
A valid IMA mineral species - grandfathered
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About Ussingite
Niels Viggo Ussing
Formula:
Na2AlSi3O8OH
Colour:
Pale to medium violet, reddish violet, colourless, white, purple
Lustre:
Sub-Vitreous
Hardness:
6 - 7
Specific Gravity:
2.48
Crystal System:
Triclinic
Name:
Named after Niels Viggo Ussing (14 June 1864, Copenhagen, Denmark - 23 July 1911, Copenhagen, Denmark), Professor of Mineralogy, University of Copenhagen, Denmark.
The structure is a unique, interrupted framework with strong H bonding. It is based on 4-, 6- and 8-membered rings of silicate tetrahedra, somewhat like these in feldspars but, as opposed to the latter, partially depolymerized.
Unique Identifiers
Mindat ID:
4122
Long-form identifier:
mindat:1:1:4122:1
IMA Classification of Ussingite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Na2AlSi3O8(OH)
Classification of Ussingite
9.EH.20
9 : SILICATES (Germanates)
E : Phyllosilicates
H : Transitional structures between phyllosilicate and other silicate units
9 : SILICATES (Germanates)
E : Phyllosilicates
H : Transitional structures between phyllosilicate and other silicate units
76.3.3.1
76 : TECTOSILICATES Al-Si Framework
3 : Al-Si Framework with other Be/Al/Si frameworks
76 : TECTOSILICATES Al-Si Framework
3 : Al-Si Framework with other Be/Al/Si frameworks
16.2.3
16 : Silicates Containing Aluminum and other Metals
2 : Aluminosilicates of Na
16 : Silicates Containing Aluminum and other Metals
2 : Aluminosilicates of Na
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 |
|---|---|---|
| Usg | 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 Ussingite
Sub-Vitreous
Transparency:
Transparent, Translucent
Colour:
Pale to medium violet, reddish violet, colourless, white, purple
Streak:
White
Hardness:
6 - 7 on Mohs scale
Tenacity:
Brittle
Fracture:
Irregular/Uneven
Density:
2.48 g/cm3 (Measured) 2.51 g/cm3 (Calculated)
Optical Data of Ussingite
Type:
Biaxial (+)
RI values:
nα = 1.504 nβ = 1.509 nγ = 1.545
2V:
Measured: 32° to 39°, Calculated: 42°
Birefringence:
0.041
Max. Birefringence:
δ = 0.041
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:
Low (negative)
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:
none
Optical Extinction:
Z angle b = 3˚
Chemistry of Ussingite
Mindat Formula:
Na2AlSi3O8OH
Element Weights:
Common Impurities:
Ca,K,Cl,H2O,S
Crystallography of Ussingite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 7.256 Å, b = 7.686 Å, c = 8.683 Å
α = 90.75°, β = 99.75°, γ = 122.48°
α = 90.75°, β = 99.75°, γ = 122.48°
Ratio:
a:b:c = 0.944 : 1 : 1.13
Unit Cell V:
399.44 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals uncommon; blocky to tabular with dominant pinacoidal forms {100}, {010}, and {001}
Twinning:
{010}
Comment:
Williams & Weller (2012) data: a=7.2474(1), b=7.6813(1), c=8.6423(1), α=90.8351(1), β=99.771(1), γ=122.581(1)
Crystal Structure
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Unit Cell | Unit Cell Packed
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) |
|---|---|---|---|---|---|---|---|
| 0000399 | Ussingite | Rossi G, Tazzoli V, Ungaretti L (1974) The crystal structure of ussingite American Mineralogist 59 335-340 |  | 1974 | Lovozero alkali massif, Russia | 0 | 293 |
| 0019374 | Ussingite | Williams E R, Weller M T (2012) A variable-temperature neutron diffraction study of ussingite; a strong asymmetric hydrogen bond in an aluminosilicate framework Physics and Chemistry of Minerals 39 471-478 | 2012 | Nakalaq, Ilimaussaq complex, Greenland | 0 | 4 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.88 Å | (70) |
| 6.35 Å | (90) |
| 4.92 Å | (70) |
| 4.18 Å | (70) |
| 3.84 Å | (70) |
| 3.47 Å | (70) |
| 2.95 Å | (100) |
| 2.69 Å | (100) |
Comments:
14-426
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 9 : Lava/xenolith minerals (hornfels, sanidinite facies) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Ussingite
Geological Setting of Type Material:
Syenite pegmatite, also sodalite-bearing xenoliths
Other Language Names for Ussingite
Common Associates
Associations Based on Photo Data:
| 61 photos of Ussingite associated with Serandite | NaMn2+2Si3O8(OH) |
| 56 photos of Ussingite associated with Vuonnemite | Na11Ti4+Nb2(Si2O7)2(PO4)2O3(F,OH) |
| 43 photos of Ussingite associated with Sodalite | Na4(Si3Al3)O12Cl |
| 39 photos of Ussingite associated with Chkalovite | Na2BeSi2O6 |
| 33 photos of Ussingite associated with Aegirine | NaFe3+Si2O6 |
| 28 photos of Ussingite associated with Umbozerite | Na3Sr4Th[Si(O,OH)3-4]8 |
| 27 photos of Ussingite associated with Steenstrupine-(Ce) | Na14Mn2+2Fe3+2Ce6Zr(Si6O18)2(PO4)6(PO3OH)(OH)2 · 2H2O |
| 21 photos of Ussingite associated with Tugtupite | (BeAlSi)Na4(SiO4)3Cl |
| 19 photos of Ussingite associated with Manganoneptunite | KNa2Li(Mn2+)2Ti2[Si4O12]2 |
| 17 photos of Ussingite associated with Sphalerite | ZnS |
Related Minerals - Strunz-mindat Grouping
| 9.EH.05 | Manganoneptunite | KNa2Li(Mn2+)2Ti2[Si4O12]2 |
| 9.EH.05 | Magnesioneptunite | KNa2Li(Mg)2Ti2[Si4O12]2 |
| 9.EH.05 | Neptunite | KNa2Li(Fe2+)2Ti2[Si4O12]2 |
| 9.EH.05 | Watatsumiite | KNa2Li(Mn2+)2V4+2[Si4O12]2 |
| 9.EH.05 | Rotherkopfite | KNa2Fe2+(Fe2+)2(Ti1.5Fe2+0.5)[Si4O12]2 |
| 9.EH.10 | Grumantite | Na(HSi2O5) · H2O |
| 9.EH.15 | Sarcolite | Na4Ca12Al8Si12O46(SiO4,PO4)(OH,H2O)4(CO3,Cl) |
| 9.EH.25 | Telyushenkoite | (Cs,Na,K)Na6[Be2Al3Si15O39]F2 |
| 9.EH.25 | Leifite | (Na,H2O)Na6[Be2Al2(Al,Si)Si15O39]F2 |
| 9.EH.25 | Eirikite | KNa6Be2(Si15Al3)O39F2 |
| 9.EH.30 | Nafertisite | Na3Fe2+10Ti2(Si6O17)2O2(OH)6F(H2O)2 |
| 9.EH.35 | Veblenite | KNa(Fe2+5Fe3+4Mn7)Nb4(Si2O7)2(Si8O22)2O6(OH)10(H2O)3 |
Fluorescence of Ussingite
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 Ussingite
mindat.org URL:
https://www.mindat.org/min-4122.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Ussingite
Reference List:
Böggild, Ο. B. (1915) Ussingit, ein neues Mineral von Kangerdluarsuk. Zeitschrift für Kristallographie, 54 (1-6). 120-126 doi:10.1524/zkri.1915.54.1.120
Rossi, Guiseppe, Tazzoli, Vittorio, Ungaretti, and Luciano (1974) The crystal structure of ussingite. American Mineralogist, 59 (3-4) 335-340
Localities for Ussingite
Showing 38 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.
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Shkatulka pegmatite, Umbozero mine, Alluaiv Mountain, Lovozersky District, Murmansk Oblast, Russia