Analysis of the Structure of Gray and Azure Glazes of Persepolis Brick, Using XRD and SEM Laboratory Methods

One method of decorating palaces during the Achaemenid period was the use of glazed colored bricks. These glazes encompass a wide range of organic and mineral compounds. This research, conducted in an experimental laboratory, aimed to understand the constituent elements of the glazes on the Persepolis bricks. The main question addressed was which elements are the major determinants of the gray and azure glaze colors on Achaemenid bricks at Persepolis? Among various methods used for mineral identification, XRD analysis was employed to identify materials and determine the phases present, while SEM was utilized to determine the elemental composition. This study focused on the structure and identification of two types of glazes: gray and azure. Samples were physically extracted with a very thin layer of glaze from the sample body. Based on the results obtained, the siliceous and porous nature of the body was confirmed, with iron and magnesium present in the glaze composition, likely part of the primary mix, contributing impurities that affected their coloration. It was also revealed that both gray and azure glazes have an alkaline structure. The findings of this study are crucial for the preservation of ancient artifacts and can guide future research in the field of historical materials.