Geological mineralogical and technological properties of Oligocene-Miocene clay deposits in altered volcanic rocks for the ceramic industry (Western Anatolia, Turkey)

Oligo-Miocene volcanic rocks cover large areas in Western Anatolia and pass laterally into terrestrial sediments, and they have economic occurrences formed by the effect of active tectonism. Alteration of these rocks developed by hydrothermal solutions reaching the surface along the active tectonic zones and formed important kaolin deposits for the ceramic industry in the region. The geological, mineralogical and technological properties of well-known kaolin deposits around canakkale and Balikesir and their importance for the ceramic industry are discussed in this study. The XRD, XRF and SEM analyses, water absorption, firing colour, firing shrinkage, viscosity, Atterberg limits and grain size distributions were analysed for the characterization of chemical and technological properties of the samples. Mineralogical composition of the altered rocks comprised kaolinite, quartz (+/- tridymite and cristobalite), feldspar (mainly sanidine, rarely plagioclase) and small amounts of haematite and/or alunite. In light of these findings, canakkale and Balikesir kaolin deposits are used in different sections of the ceramic industry such as for ceramic tiles, vitrified ceramics and insulators in terms of their industrial properties and the studied deposits developed with different degrees of alteration