Identification and characterization of phyllosilicate minerals from Republic of Macedonia by vibrational spectroscopy

Identification and characterization of several phyllosilicate minerals collected from the Republic of Macedonia: Mg3Si2O5(OH)4; antigorite, (Mg,Fe2+)3Si2O5(OH)4; talc, Mg3Si4O10(OH)2; clinochlore, (Mg,Fe2+)5Al(Si3Al)O10(OH)8; cymrite, BaAl2Si2O8·H2O; muscovite, KAl2(Si3Al)O10(OH,F)2; phlogopite, KMg3(Si3Al)O10(F, OH)2; montmorillonite, (Na,Ca)0..33(Al, Mg)2Si4O10(OH)2·nH2O; sherindanite, (Mg,Al)6(Si,Al)4O10(OH)8 and biotite, K(Mg,Fe2+)3AlSiO10(OH,F)2 is performed using their infrared and Raman vibrational spectra. In contrast to Raman spectra, the above-mentioned minerals showed IR spectral similarities in the region bellow 1200 cm-1 mainly due to their common structural characteristics. The bands appearing in the 1100-900 cm-1 spectral region were prescribed to ν(Si-O-Si)modes, whereas most of the lower-frequency bands were interpreted as either δ(OH) or δ(Si-O-Si) vibrations. The presence of sharp peak at 1630 cm-1, registered only in the infrared spectra of cymrite and montmorillonite, enables to discriminate between hydroxide and water-containing minerals. Various types of ion substitutions, which appear in this group of minerals, sometimes could led to wrong identification. Therefore, the authenticity of the three samples, muscovite (Nezhlevo), biotite (Chanishte) and sherindanite (Sivets), was checked with results obtained from chemical composition analysis. (Author)