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

Crystal structure of Azurite

Formula:

Cu3(CO3)2(OH)2

Crystal Data:

Crystal System: Monoclinic - Prismatic
Point Group: 2/m

Cell Data:

Space Group: P21/a, a = 5.008, c = 10.336, Z = 2

Using the mouse (click here for more information)

Density (calc.) = 3.79 and V = 302.25 Å3
Element color: Cu, C, O, H
Azurite sample
Azurite

Sample no. 5397 from the "Mineralogy and Petrography Museum Grigore Cobălcescu" of "Alexandru Ioan Cuza" University, Iaşi.

Origin: Namibia.




Click image to enlarge
Raman spectrum and vibrations of Azurite
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 azurite (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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CO3 polyhedra on CO3 polyhedra off 		Vibrations:
766 cm-1 - ν4b (E') 835 cm-1 - ν2 (A"2) 1097 cm-1 - ν1 (A'1) 1435 cm-1 - ν3a (E')

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


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Interpretation of Raman spectrum of Azurite

The azurite spectrum is characterized by several lines that cover the spectral range 200-1600 cm-1. The bands observed up to 600 cm-1 are assigned to the translations of (Cu, CO3), those observed up to 1600 cm-1 are assigned to CO3 complex (Frost et al., 2002). The Raman spectrum of our azurite does not show the O-H stretching band at about 3400 cm-1.

Azurite has a characteristic intense band at 404 cm-1. The symmetric stretching band of carbonate ion is observed at 1097 cm-1, this band is assigned to the ν1 symmetric stretching vibration. The band attributed to the carbonate (ν3) asymmetric stretching vibration is observed at 1425 cm-1 and 1459 cm-1. One band is observed in the Raman spectrum of azurite at 766 cm-1 and is assigned to the ν4 mode. The band of 835 cm-1 was assigned to the ν2 asymmetric bending vibration. A number of bands with different intensities are observed in the lowest spectral shift of the Raman spectrum of azurite (250, 285, 339, 404 and 544 cm-1). These Raman lines are assigned to the lattice modes. The O-H out-of-plane bending mode of azurite was reported at 939 cm-1. We have not found any information available for Raman line of 1579 cm-1. It is probably due to the O-H bending mode, in agreement with Nakamoto (1997).


Buzgar et al., 20091 Frost et al., 2002 Mattei et al., 2008 Assignment
250, 285, 339,
404, 544		 112, 131, 139, 144,
154, 165, 171, 179,
194, 215, 237, 248,
265, 281, 332, 387,
400, 414, 540		 157, 174, 182, 240,
250, 267, 282, 332,
387, 402, 542		 T(Cu,CO3)
766 739, 764 744, 768 ν4 symmetric CO3 deformation
835 815, 835 840 ν2 asymmetric CO3 deformation
939 952 937 O-H out-of-plane
1097 1095 1099 ν1 symmetric CO3 stretching
1425
1459		 1421
1431		 1422, 1433,
1462		 ν3 asymmetric CO3 stretching
1579 O-H bending mode
NO 3424, 3446 3431 O-H stretching mode
NO = not observed
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]

• FROST R. L., MARTENS W. N., RINTOUL L., MAHMUTAGIC E., KLOPROGGE J. T. (2002) - Raman spectroscopic study of azurite and malachite at 298 and 77 K. Journal of Raman Spectroscopy, 33, p. 252-259 [link]

• MATTEI E., VIVO G., SANTIS A., GAETANI C., PELOSI C., SANTAMARIA U. (2008) - Raman spectroscopic analysis of azurite blackening. Journal of Raman Spectroscopy, 39, p. 302-306 [link]