Reductive dissolution and Mossbauer spectroscopic study of Fe forms in the fine fractions of Slovak Fe-rich bentonites

Four samples of <2 ~tm fractions of Fe-rich bentonites from tile area of the Zvolensk~ kotlina Basin (Slovakia) have been investigated by MiSssbauer spectroscopy and reductive dissolution in ammonium hydrogen oxalate (pH = 2.7). Both methods have shown the presence of goethite in the samples. The relative amount of Fe bound in goethite varied more within the samples of bentonite from Zvolensk~ Slatina, which was redeposited after transport over a short distance, than in the authigenically altered bentonite from Hrochot'. The results of the fits of the reductive dissolution curves suggest size distribution, variation in Al-for-Fe substitution in goethite particles and/or different access of extracting solution to goethite particles present in the analysed fine fractions of bentonites.