Bentonite from the Central Slovakia Volcanic Field – A Prospective Raw Material for Polish Industry

Abstract This paper summarizes information about recently worked bentonite deposits in Slovakia and presents the results of studies on bentonite from the Central Slovakia Volcanic Field (CSVF). The authors compared the mineralogy of commercial bentonites exploited in the Stara Kremnička (Jelšový potok), Kopernica, and Hliník nad Hronom deposits. X-ray diffraction (XRD), chemical analyses and microscopy showed that the main component is montmorillonite (37-88%), followed by opal C/CT (5-25%), clinoptilolite (up to 15%), feldspars (3-12%), quartz (up to 8%), biotite (2-5%), and kaolinite (up to 2%). The microscopic imaging provided information valuable for the technological assessment of bentonites, particularly the evaluation of mineralogy determined by XRD. The low variability of the mineral composition of commercial bentonites exploited in the western CSVF, together with the significant reserves and localization of deposits close to the Polish-Slovak state border prove that this raw material deserves more attention from Polish industry.