Dolomite Raman spectra - Romanian Database of Raman Spectroscopy

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

Crystal structure of Dolomite

Formula:	CaMg(CO₃)₂
Crystal Data:	Crystal System: Trigonal - Rhombohedral
	Point Group: 3
Cell Data:	Space Group: R 3, a = 4.842, c = 15.95, Z = 3
Using the mouse (click here for more information)	Density (calc.) = 2.711 and V = 367.78 Å³
		Element color: Ca, Mg, C, O

Dolomite sample

Sample no. 5451 from the "Mineralogy and Petrography Museum Grigore Cobălcescu" of "Alexandru Ioan Cuza" University, Iaşi.

Origin: Fiesch - Switzerland.

Click image to enlarge

Raman spectrum and vibrations of Dolomite

Interpretation of Raman spectrum of Dolomite

In this study only ν₁ (1087 cm^-1), ν₄ (714 cm^-1) bands are observed in the Raman spectrum, ν₂ and ν₃ modes are absent. The external vibration mode observed at 285 cm^-1 are due to the relative translations between the cation and anionic groups (Gunasekaran, 2006).

Buzgar et al., 2009¹	Gunasekaran et al., 2006	Huang et al., 1960	Assignment
	187	179	T(Ca, Mg, CO₃)
285	309	304	T(Ca, Mg, CO₃)
714	733	725	ν₄ symmetric CO₃ deformation
			ν₂ asymmetric CO₃ deformation
1087	1106	1100	ν₁ symmetric CO₃ stretching
NO	1450	1445	ν₃ asymmetric CO₃ stretching
NO	1765		ν₁ + v₄

NO = not observed

The difference in site symmetries for dolomite and calcite results from substitution of Mg atom for one of the two Ca atoms for about each molecular oxygen atom. Thus the IR and Raman spectra of dolomite resemble those of calcite. In literature, Gunasekaran et al. (2006) and Huang et al. (1960) have reported bands for the ν₃ vibrational modes of CO₃ group (1450, respectively 1445 cm^-1), values that in this study were not observed. Also, Gunasekaran has reported a band at 1765 cm^-1 assigned to ν₁ + ν₄ combination.

References

• The Mineralogy Database [link]

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

• ¹BUZGAR N., APOPEI A. I. (2009) - The Raman study on certain carbonates. Analele Stiintifice ale Universitatii “Al. I. Cuza” - Iasi, Tome 55, issue 2, 97-112 [link]

• GUNASEKARAN S., ANBALAGAN G., PANDI S. (2006) - Raman and infrared spectra of carbonates of calcite structure. Journal of Raman Spectroscopy, 37, p. 892-899 [link]



Element color: C, 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 dolomite (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 CO₃ polyhedra on CO₃ polyhedra off	Vibrations: 714 cm^-1 - ν_4b (E') 1087 cm^-1 - ν₁ (A'₁) Vibration on Vibration off	Download spectrum: Raman spectrum .txt Raman spectrum .spc Vectors on Vectors off Measure distances Delete measure Axes on Axes off

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