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

Crystal structure of Celestine

Formula:

SrSO4

Crystal Data:

Crystal System: Orthorhombic - Dipyramidal

Point Group: 2/m 2/m 2/m

Cell Data:

Space Group: Pbnm , a = 8.359, b = 5.352, c = 6.866, Z = 4

Using the mouse (click here for more information)

Density (calc.) = 3.97 and V = 307.17 Å3
Element color: Sr, S, O
Celestine sample
Celestine

Sample no. 5515 from the "Mineralogy and Petrography Museum Grigore Cobălcescu" of "Alexandru Ioan Cuza" University, Iaşi.

Origin: Gloucestershire - England.




Click image to enlarge
Raman spectrum and vibrations of Celestine
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 celestine (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:
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Spin on Spin off
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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


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Interpretation of Raman spectrum of Celestine

For celestine, Raman spectrum is also dominated (like barite and anglesite) by an intense ν1 band (1003 cm-1) and the other characteristic vibrational modes of SO4 group: ν2 - 461 cm-1; ν3 - 1111 cm-1, and 1160 cm-1; ν4 - 622 cm-1 and 641 cm-1. These values are similar to those reported in the literature.


Celestine Assignments
Buzgar et al., 20091 Kloprogge et al., 2001
453 ν2 SO4
461 460
622 620 ν4 SO4
641 640
659
1003 1003 ν1 SO4
1096 ν3 SO4
1111 1112
1160 1162

The peak corresponding to the symmetric stretching mode (ν1) of the S-O bond in the sulfates appears to be the strongest in the Raman scattering intensity. The wavenumber of a Raman shift is determined by the bond strength and the atomic masses (Fadini and Schnepel, 1989). Therefore, the ν1 wavenumber is a function of S-O stretching force constant in sulfates and increases with an increase in the force constant. The force constant of SO4 tetrahedra were calculated from the bond lengths and the infrared absorption frequencies by Miyake et al. (1978).


Wavenumber of the v1 vibrational Raman mode vs. atomic mass of the cations for barite group

Figure 1. Wavenumber of the ν1 vibrational Raman mode vs. atomic mass of the cations for barite group.

The stretching force constants are: for barite K = 6,27 md/Å; for celestine K = 6.34 md/Å; and for anglesite K = 5.98 md/Å. Therefore, this systematic wavenumber shift is largely due to the increase of mean force constants because of substitution of larger cations in the M sites (Lee et al., 2005). Also, the wavenumber decreases with an increase of the atomic mass of the cations. An example for ν1 mode is presented in figure 1, where the atomic masses are: Sr = 87.62 u; Ba = 137.32 u; Pb = 207.2 u.
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]

• Fadini, A., Schnepel, F. M. (1989) - Vibrational spectroscopy methods and applications. Ellis Horwood Limited.

• Miyake, M., Minato, I., Morikawa, H., Iwai, S. (1978) - Crystal structures and sulphate force constants of barite, celestite and anglesite. American Mineralogist, 63, 506–510. [link]