Physicochemical characterizations of clay as a raw material for pottery from Rendeng, Malo, Bojonegoro

Two clay materials from Rendeng, Malo, Bojonegoro were used traditionally in pottery industry. They were Tanah Pegunungan (TP) and Tanah Proses Pegunungan (TPP). This study was about its mineralogy and the physicochemical in order to evaluate their potential suitability as a raw materials in pottery application. The physical properties were identified by consistency limit using Atterberg method. The chemical compositions were carried out by XRF technique to establish the mineralogical compositions using XRD and FTIR techniques. The physical characterization showed that clay from Rendeng, Malo, Bojonegoro were less plastic type and kaolinite mineral type. The chemical compositions of TP clay indicated that SiO₂, Al₂O₃, and CaO were major elements, while K₂O and TiO₂ were less abundant. Too high CaO level would affect the smoothness of the fine pottery due to the large number of chalk grains. While, chemical composition of TPP clay indicated that SiO₂, Al₂O₃, and FeO were major elements. The difference in the composition of the high CaO and FeO content in each sample of TP and TPP respectively would produce a unique pottery. Quartz, Feldspar, and Kaolin dominated in all samples. Based on the analysis, TP and TPP clay materials were only suitable as raw materials for making pottery because the minerals did not fulfill the SII quality requirements in the manufacture of advance ceramics or other benefits.