Geological, mineralogical and geochemical features of the kaolin occurrences the Hallaçlar (Banaz-Uşak)

Kaolin deposite located in Hallaçlar village in Banaz, Uşak is related with Yeniköy formation?s sandstone-siltstone levels and formed as a result of the alteration of these rocks. Five different alteration zones in 27 m thickness formed by successive leves of unaltered sandstone-siltstone, silisified sandstone, silis zone, kaolenized sandstone and kaolin has been identified. The harmony of the kaolin levels with other alteration zones, observation of the sandstone-siltstone and kaolin?s transition indicates that parent rock?s being sandstone-siltstone. The increasing of alteration degree from top to bottom occured by effects of hydrothermal process. Kaolinite minerals have been identified densely shaped in psedohegzagonal forms throught the Scanning Electrone Microscope (SEM) investigations. Apart from kaolinite, minerals like alunite, illit/mica, quartz, calcite, dolomite and hematite minerals have been identified in X-ray Diffraction (XRD) analyses. In the mass change accounts, it was observed that major oxides such as SiO2, MgO, CaO, Na2O and K2O and trace elements such as Ba, Co, and Ni depleted the quantity of Al2O3, Fe2O3, Ga, Sr, V ve ?REE enriched. According to the results of field studies, mineralogical investigations, major, trace elements and stable isotopes, Hallaçlar kaolin deposits was occured from the alterastion of sedimentary rocks such as sandstone-siltstone by hydrothermal waters having over 100 oC heatness and have hypogene origin.