Comprehensive characterization of bentonites from Croatia and neighboring countries

• Published in: Geologia Croatica Vol. 73; no. 1; pp. 29 - 48
• Main Authors: Gverić, Zvonka, Hanžel, Darko, Kampić, Štefica, Pleša, Andrej, Tibljaš, Darko
• Format: Journal Article Paper
• Language: English
• Published: Zagreb Institut za Geoloska Istrazivanja 01-01-2020; Hrvatskigeološkiinstitut
• Subjects: Ammonium; Ammonium compounds; Analytical methods; Bentonite; Calcium; Casting; Cations; Chemical analysis; Chemical properties; Chemicophysical properties; Classification; Clay; Emission analysis; Inductively coupled plasma mass spectrometry; Interlayers; Mineralogy; Mossbauer spectroscopy; Sediments; Smectites; Sodium; Spectroscopy; Thermal analysis; Bosnia-Hercegovina; Slovenia; Croatia
• ISSN: 1330-030X; 1333-4875
• DOI: 10.4154/gc.2020.02

Bentonites are an important industrial resource and are also interesting from the mineralogical point of view. The main component of bentonites is a mineral from the smectite group in which chemical and structural variations, influencing bentonite properties, provide a great deal of interesting research topics. The aim of this study was to better describe bentonites from 11 known deposits from Croatia and neighbouring countries: Bednja, Bunarić, Draga, Divoselo, Sjeničak, Paripovac, Lončarski vis and Poljanska Luka (Croatia), Zaloška Gorica (Slovenia), Šipovo (Bosnia and Herzegovina) and Vranjska Banja (Serbia). Thirteen samples were analysed using several available techniques in order to obtain the data necessary for currently accepted bentonite classification. The mineralogical composition was analysed using XRD and FTIR, and crystallochemical properties were investigated by thermal analysis, CEC determination with ammonium index cations, chemical analyses (ICP-AES and ICP-MS) and Mössbauer spectroscopy. The results showed that the main mineral constituent of most local bentonite deposits is a Fe-poor smectite, with a predominantly medium layer charge mostly as a result of octahedral substitutions, with calcium or sodium cations occupying the interlayer. Nevertheless, the variations between samples are prominent enough to provide a good overview of the range of crystallo-chemical properties which exist in different smectites resulting in varying bentonite properties.