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Syngenite: Crystal structure | Sample photo | Raman spectrum | Interpretation | References

Crystal structure of Syngenite

Formula:

K2Ca(SO4)2•(H2O)

Crystal Data:

Crystal System: Monoclinic - Prismatic

Point Group: 2/m

Cell Data:

Space Group: P 21/m , a = 9.55,b = 7.13, c = 6, Z = 2

Using the mouse (click here for more information)

Density (calc.) = 2.76 and V = 394.63 Å3
Element color: K, Ca, S, O, H
Syngenite sample
Syngenite

Sample no. 5559 from the "Mineralogy and Petrography Museum Grigore Cobălcescu" of "Alexandru Ioan Cuza" University, Iaşi.

Origin: Kalusch - Ukraine.




Click image to enlarge
Raman spectrum and vibrations of Syngenite
Element color: S, O Toggle Grid Toggle Coordinates Reverse Spectrum

Click to in the Raman spectrum. To see the vibrations click on one of them (highlight region) and it (the selected vibration) will appear on the right side of the Raman spectrum.
Below spectra are various settings, and other vibrations of syngenite (which are not present in this spectrum).
You have the possibility to zoom in the spectrum by selecting a spectral region you need to be increased (along axis x); to zoom keep the left mouse-click continously pressed, drag (to left or to right) and release the left button. To return to the initial size spectrum, press the right click on the spectrum -> Zoom -> Reset View.
Model type:
Sticks Ball-and-Sticks (1) Ball-and-Sticks (2) CPK (Spacefill)

Orientation:
Reset view Front view Back view Left view Right view Top view Bottom view 		Background color:
Reset White(1) Black

Spin on Spin off
Symbols on Symbols off
SO4 polyhedra on SO4 polyhedra off 		Vibrations:
ν2 SO4 ν4 SO4 ν1 SO4 ν3 SO4

Vibration on Vibration off 		Download spectrum:
Raman spectrum .txt Raman spectrum .spc


Vectors on Vectors off
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Axes on Axes off
Interpretation of Raman spectrum of Syngenite

The syngenite Raman spectrum is governed by two strong bands at 982 cm-1 and 1006 cm-1, that can be assigned to the ν1 symmetric stretching modes of two sulfate groups. The bands at 1084 cm-1, 1120 cm-1, 1143 cm-1 and 1167 cm-1 can be ascribed to the splitting of the ν3 mode of both sulfate groups. The ν2 mode is present at 442 cm-1, 477 cm-1 and 495 cm-1. The sulfate ν4 mode can be observed at 641 cm-1 and 663 cm-1. The O-H stretching modes have been found at 3305 cm-1 and the vibration of the (M, H2O) at 240 cm-1.


Syngenite Assignments
Buzgar et al., 20091 Kloprogge et al., 2002
240 T(M, H2O)
424 ν2 SO4
442 441
477 471
495 491
641 641 ν4 SO4
663
982 981 ν1 SO4
1006 1004
1084 ν3 SO4
1120 1117
1143 1138
1167 1166
3305 νH2O
References

• The Mineralogy Database [link]

• Crystal data (.cif file) from the American Mineralogist Crystal Structure Database [link]

• 1BUZGAR N., BUZATU A., SANISLAV I. V. (2009) - The Raman study on certain sulfates. Analele Stiintifice ale Universitatii “Al. I. Cuza” - Iasi, Tome 55, issue 1, 5-23 [link]

• Kloprogge, J. T., Schuiling, R. D., Ding, Z., Hickey, L., Wharton, D., Frost, R. L. (2002) - Vibrational spectroscopic study of syngenite formed during the treatment of liquid manure with sulphuric acid. Vibrational Spectroscopy, 28, 209-221 [link]