Advances in characterization of colourful residues unearthed in Persepolis West craft zone using microscopic and spectroscopic techniques

The microstructure and chemical composition of blue and green pellets, coloured lump pigments and a metal scrap excavated in Persepolis West (Fars, Iran), by the Iranian-Italian Joint Archaeological Mission in Fars in 2008–09, were investigated to clarify their origin and production techniques. The Persepolis West urban area has its eastern limit about five hundred meters away from the Persepolis Terrace and extends for about 1 km in a westward direction. Due to the presence in this area of various kilns and other remains, the existence of a craft zone connected with the construction of imperial and élite buildings in Persepolis was proposed. The colourful residues were submitted to integrated investigations using portable X-ray fluorescence spectrometry, digital and polarized light microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, ATR-FTIR and Raman spectroscopy. The integrated analyses allowed to identify azurite, malachite, Egyptian blue, glauconite, yellow and red ochre with hematite, magnetite and goethite. Proteinaceous material was detected only in one red lump. These pigments are in accordance with the palette used to paint the palaces of the Persepolis Terrace, thus supporting the hypothesis that in Persepolis West craft zone, there was a laboratory for production of pigments. The microscopic features of the lumps and their peculiar shape confirmed a local manufacturing process. Moreover, the diopside presence related to the Egyptian blue production, as well as the discovery of a bronze scrap with a crust of Egyptian blue also suggested that this pigment was manufactured locally.