Minerals from Macedonia (original) (raw)
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MINERALS FROM MACEDONIA IX. DISTINCTION BETWEEN SOME RHOMBOHEDRAL CARBONATES BY FT IR SPECTROSCOPY
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.
Minerals from Macedonia. IV. Discrimination between some carbonate minerals by FTIR spectroscopy
Neues Jahrbuch für Mineralogie - Abhandlungen, 2002
The use of FTIR spectroscopy to distinguish between some geologically important carbonate minerals (calcite -CaCO 3 , aragonite -CaCO 3 , siderite -FeCO 3 , magnesite -MgCO 3 and dolomite -CaMg(CO 3 ) 2 ) originating from Macedonia and to detect mineral impurities in them is considered. It was shown that the series of the studied isomorphous calcite type minerals is an ideal test case for the evaluating the influence of the corresponding cation upon the band frequencies of the carbonate n 3 , n 2 and n 4 modes in their infrared spectra. It enables to distinguish the isomorphous calcite type carbonates from one another. In the course of the quantitative determination of the composition of mixtures it is shown that the limit of detection of impurities of aragonite in the mixtures with calcite (or other calcite type minerals) is around 1 wt %. The spectra of natural calcite and siderite were compared to those of their synthetic analogues.
A b s t rae t : The appearance of the VI mode (1083 em I) in the Ff IR spectrum of aragonite (absent in the spectrum of calcite) as well as the lower frequency of the V4 mode in the spectrum of aragonite (713 and 700 emI) than in that of calcite (732 emI) made it possible to detect the presence of aragonite in calcite and to determine its content. Similarly, the higher frequency of the V4 mode in the spectrum of calcite (732 emI) than in aragonite (713 and 700 em I) was used to detect impurities as well as to determine the content of calcite in aragonite.
Among the rich ore deposits present in Macedonia, the silicate minerals are the most numerous group. The great majority of these minerals appear as rather large and well formed single crystal aggregates in the nature. Sometimes, however, some of the mineral species appear in association with other minerals whose crystals are not well developed. Here an overview of the basic morphological, physico-chemical and crystallographic characteristics of the most typical silicates collected from various localities within the Republic of Macedonia is given. The mineralogical and petrological features of the localities where the specimens are collected from are presented as well. Also an attempt to identify the minerals using the FT IR spectroscopy and to classify them according to their structural characteristics is performed. The identification of the minerals was based on the comparison of the infrared spectra of our specimens with the corresponding literature data for the mineral species originating all over the world. The coloured pictures of all studied silicate minerals are presented as well.
Minerals from Macedonia XIII: Vibrational spectra of some commonly appearing nesosilicate minerals
Journal of Molecular Structure, 2005
The vibrational (infrared and Raman) spectra of seven common nesosilicate minerals [almandine, Fe ] in the region from 1200 to 370 cm K1 (infrared, for staurolite from 3750 to 3250 cm K1 , as well) and from 1200 to 100 cm K1 (Raman) are studied. The observed spectral behavior is discussed in terms of the structural characteristics of orthosilicates (nesosilicates) where no oxygen atoms are shared between the adjacent SiO 4 tetrahedra. In spite of some differences, in general, rather expressed similarity among the infrared spectra of the minerals are observed in the region below 1200 cm K1 , mainly due to their common structural characteristics. The similarity is especially expressed in the case of the isomorphous almandine and spessartine garnets, which form solid solution. Except staurolite, all mentioned minerals are nominally anhydrous and do not contain OH groups. The similarity between the Raman spectra of the studied minerals is less expressed compared to the IR analogues. The vibrational spectra of the studied mineral samples are compared with the corresponding literature data for the analogous mineral species originating all over the world and used for mineral identification. q 2004 Published by Elsevier B.V.
Journal of Molecular Structure, 2007
The results of the identification of six sheet silicates originating from the Republic of Macedonia: chrysotile, Mg 3 Si 2 O 5 (OH) 4 ; antigorite, (Mg,Fe 2+ ) 3 Si 2 O 5 (OH) 4 ; talc, Mg 3 Si 4 O 10 (OH) 2 ; clinochlore, (Mg,Fe 2+ ) 5 Al(Si 3 Al)O 10 (OH) 8 ; cymrite, BaAl 2 Si 2 O 8 AEH 2 O and montmorillonite, (Na,Ca) 0.33 (Al, Mg) 2 Si 4 O 10 (OH) 2 AEnH 2 O, using vibrational spectroscopy were presented. The above mentioned minerals show IR spectral similarities in the region below 1200 cm À1 , mainly due to their common structural characteristics being mostly expressed in the case of isomorphous chrysotile and antigorite. Three medium bands observed in the highest wavenumber region of clinochlore originate from the stretching vibrations of the three crystallographically different OH groups. A sharp peak at 1630 cm À1 was noticed only in the IR spectra of cymrite and montmorillonite being discriminative pattern between hydroxide and water-containing minerals. The similarities between the Raman spectra (1200-100 cm À1 ) were less expressed confirming that Raman technique is more sensitive to compositional changes as well as to structural disorder. Identification was based on the comparison of the obtained results with the literature data for the corresponding minerals originating from other localities all over the world.
Turkish Journal of Earth Sciences, 2009
The Ržanovo deposit lies within the western ophiolite belt of the Vardar zone. Its main geological units are discussed in terms of their mineralogy, petrology and petrological evolution. Minerals observed include: magnetite, hematite, clinochlore, talc, sepiolite, magnesioriebeckite, lizardite, dolomite, phlogopite, stilpnomelane, quartz, albite, pyrite, maghemite, pyrrhotine, digenite and millerite. Some minerals had non-distinct morphologies and ambiguous characteristics, preventing identification on the basis of physical properties alone. Thus, some of the minerals (magnetite, hematite, talc, dolomite, olivine, calcite, aragonite and brucite) as well as some serpentine minerals (antigorite and chrysotile) were identified by vibrational spectroscopy. Difficulties in identification by IR spectroscopy and Raman were considered to be the result of contamination (i.e., inclusions of other minerals in the analyzed crystals).