شناسایی ساختار رنگ سفالینه های دوره مفرغ متأخر شرق دریاچه ارومیه؛ بر مبنای نمونه های کؤل تپه عجب شیر

Although the pottery is found in a massive amount in archaeological discoveries, these materials are the most important materials for different orientations in studies on the ancient people. One aspects of the study on ancient potteries, is the investigation about the painting and different colorants used for decorating potteries in variety patterns with different colors. This study aims to explore the ancient people knowledge and their experiments on creation of color by making up dying materials that could be found close to their dwells. The present work represented an attempt to discern experimentally the base and chemical composition of colorants used as decorative elements on ancient ceramics. Thus, five pieces of late Bronze painted pottery of the eastern Lake Urmia Basin (from the archaeological site of Kul Tepe of Ajabshir) were singled out. First, to determine whether the paint came from organic or inorganic sources and also to identify the existing anions and cations the Fourier-Transform Infrared Spectroscopy (FT-IR) technique was employed. The results demonstrated that the used coloring material has a mineral origin, where the sharp and strong peak at 465 cm-1 of the spectrums confirmed that the nature of coloring agents consists of iron oxides. Next, for elemental analysis and studying the chemical structure and composition of the colorants Scanning Electron Microscope-Energy Dispersive X-Ray analysis (SEM-EDX) was used. SEM-EDX analysis result demonstrated the presence of iron and manganese (Mn) content alongside other component elements of the ceramic bodies including SiO2, MgO, Al2O3, and K2O, where the results tallied with the FT-IR spectrums. On the basis of elemental analysis results, it could be said that iron oxides are the main components of coloring agents, where they could produce a variety of colors, ranging from red to dark brown. Moreover, the presence of manganese make the paintings darker, and consequently, the brighter nature of paintings of sample no. 3 of Kul Tepe and sample no. 1 of Haftvan could be the consequence of the miserable amount of this element (1.77 and 0.49%, respectively). Finally, in order to confirm and complete the study, the specimens were subjected to X-Ray Diffraction analysis (XRD). This experiment also showed that the pigments used in ornamenting the sherds were mineral and comprised of Agite mineral (Ca(Fe, Mg)Si2O6), as the coloring mineral, alongside other minerals including sodic and calcite feldspars. The results obtained are in good agreements with the geology of the region, where the feldspars exist as the main minerals of both sites. Therefore experimental analysis on the pigments structure that used in the painting of Kul Tepe Urmia ware decorations in different ways and various laboratory equipments demonstrated that the pigments used in the pottery decorations have mineral source and presented various iron compounds in the paint of decorations. As result of this study, the presence of iron compounds in the soil of the Kul Tepe region, it could be said the ancient people did use the natural sources of colorants for decoration of their potteries. Moreover, the techniques and materials used for decoration of the potteries were the same at both side of the Lake Urmia.