the studied stela exhibited significant color changes in the Egyptian blue and Egyptian green pigments, a common occurrence in these synthetic pigments. The presence of chlorides catalyzed a decay process known as "bronze disease." This transformation was attributed to the replacement of hydroxide ions by chloride ions, leading to the formation of hygroscopic soluble metal chlorides. In the presence of Egyptian blue (Cuprorivaite, CaCu(Si4O10)), chloride-induced color alterations occurred due to the formation of green copper chlorides, such as green atacamite and paratacamite. These changes were the result of the migration of copper (Cu) and chloride (Cl) ions, ultimately leading to the precipitation of atacamite, which could further transform into paratacamite or a new pigment material known as wollastonite green (CaCu)3(Si3O9). The discolouration was attributed to the instability of the Egyptian blue pigment in the glassy phase, influenced by an increased silicate content in the alloy, as shown in Figs 2-4.