Technical study of chemical compounds in the glaze of the tiles in the Green dome of Kerman

Identifying the materials used in the construction and decoration of the building is of great importance to complete the discussion of a historical monument and its restoration. One of the buildings that need to be studied in this field as a prominent and valuable building is the green dome of Kerman that its mosaic tiles are known as the oldest mosaic tiles in Iran. And so far no study has been done on them. The colors of the tiles of this building are black, azure, white, and turquoise, yellow and green. This research has been done in the field of applied research to better understand the architecture of the past and the techniques of making architectural decorations. In order to achieve the goal, has been used the method of scanning electron microscopy equipped with X-ray energy separation analysis to identify glaze elements and body petrography in the studied samples. The results show that the black color of the glaze is due to the presence of substances such as manganese in the glaze. The turquoise glaze color is obtained by combining copper compounds in the rich glaze in alkaline elements such as potassium. Also, lead antimony, iron oxide and cadmium sulfate cause yellow glaze and tin oxide and tin sulfate in white glaze cause white color. The azure color is also caused by cobalt oxide and cobalt sulfate, and the green color of the glaze is due to the presence of copper sulfate and iron. Petrographic analysis, XRD and XRF analysis for qualitative identification of minerals, existing phases, and elemental analysis of 4 samples of the tile body, shows that quartz has been used as a filler and there are calcareous soils in the bodies. Petrographic and XRD results on tile biscuits indicate oxidation baking environment and baking temperature less than 800 degrees for three samples BL, B-2, and B-4 and temperature above 850 for sample G-4.