Azurite [Cu2+ 3 (CO 3 ) 2 (OH) 2 ] and malachite [Cu 2+ 2 (CO 3 )(OH) 2 ] are both monoclinic hydroxy carbonates of copper. The Raman spectra of these two minerals were collected at both 298 and 77 K together with the single crystal Raman spectra of azurite at 298 K. The spectra of both azurite and malachite contain modes of three separate vibrational groups: OH, CO 3 and Cu-O. Accordingly, for azurite the bands at 3453 and 3427 cm −1 have been assigned as the O-H stretching mode with the O-H bending modes found at 1035 and 952 cm −1 . Malachite displays two hydroxyl stretching bands at 3474 and 3404 cm −1 at 298 K which shift to 3470 and 3400 cm −1 at 77 K while O-H out-of-plane bending modes are found at 1045 and 875 cm −1 . For the carbonate group, bands are observed at 1090 cm −1 (n 1 ), 837 and 817 cm −1 (n 2 ), 1490 and 1415 cm −1 (n 3 ) and 769 and 747 cm −1 (n 4 ). The effect of collecting the spectra at 77 K results in considerable band narrowing. The Raman spectra of the single crystals of azurite show the orientation dependence of the vibrational modes. A mechanism for n 2 splitting is proposed whereby vertical carbonate ions couple to form an in-phase and out-of-phase bending modes. Combination of these vibrational modes such as n 1 + n 3 , n 1 + n 3 , n 1 + n 4 and 2n 2 are found at 2530, 2414, 1860, and 1670 cm −1 , respectively. IR bands for the Cu-O stretching modes are observed at 495 and 400 cm −1 , while Cu-O bending modes occur at 455 and 345 cm −1 . Bands at 305 and 240 cm −1 are assigned to the O-Cu-OH bending modes. The Raman out-of-plane bending modes are found at 194 and 170 cm −1 . For the carbonate group, infrared bands are observed at 1095 cm −1 (n 1 ), 834 and 816 cm −1 (n 2 ), 1430 and 1419 cm −1 (n 3 ) and 764 and 739 cm −1 (n 4 ). Combination of the CO 3 vibrational modes n 1 + n 4 is observed at 1860 cm −1 . IR bands for Cu-O stretching modes are observed at 580, 570 and 505 cm −1 .

Middle Infrared Spectroscopy (Mid-IR) and Infrared Emission Spectroscopy (IES) were employed to characterise Cu-exchanged montmorillonites, which were derived from two different types of montmorillonite clays, Ca-exchanged montmorillonite (Cheto clay) and Na-exchanged montmorillonite (Miles clay). Copper was exchanged under both acidic and basic conditions at different Cu/clay ratios. All Cu-exchanged montmorillonites experienced a shift in most of non-lattice bands, with hydroxyl bands playing a major role in the characterisation of the clays. Furthermore, a relationship between the ratio of bands at 3630 and 3500 cm(-1) and the Cu concentration of the starting solutions was indicated and used to compare the degree of cation exchange between two preparation methods. Two dehydration stages were observed in the IES experiments. Additional bands were observed in all Cu-exchanged montmorillonites prepared with the 'basic conditions method,' and these bands were assigned to ammonia molecules trapped within the clay structure or absorbed on the surface of the clay.