Minerals from Macedonia (original) (raw)

The FT IR spectroscopy is used in order to discriminate between the calcite group (calcite, CaCO 3 ; magnesite, MgCO 3 ; siderite, FeCO 3 ) as well as the dolomite group (dolomite, CaMg(CO 3 ) 2 ; kutnahorite, CaMn(CO 3 ) 2 ) of rhombohedral carbonate minerals originating from Macedonia. Although both groups of the studied minerals share essentially the same structure, being collectively called rhombohedral carbonates, significant frequency differences between the corresponding ν 3 , ν 2 and ν 4 active modes in their FT IR spectra are observed. The frequency variation is particularly expressed in the case of the ν 4 mode. It enables to distinguish the studied five geologically important carbonate minerals from one another as well as to determine the presence of impurities of some minerals in the corresponding two-component mixtures. It is (e.g.) shown that the low limit of detection of impurities of calcite in dolomite and vice versa amounts about 1 wt %. The effect of the sample powdering extent on the spectral appearance is studied as well. An elemental analysis on three morphologically different siderite mineral species with identical infrared spectra as well as for two kutnahorite samples whose infrared spectra are also identical is performed.