Characterization of the pigments used to decorate an Egyptian death mask from the Ptolemaic period (3rd century BC) using XPS, Raman spectroscopy, and SEM-EDS

F. S. GARD; E. B. HALAC; DAIZO, M. BELÉN; M. REINOSO; SANTOS, D.; P. B. BOZZANO

San Luis

Encuentro; VIII Encuentro de Física y Química de Superficies; 2018

Universidad Nacional de San Luis

In general, knowledge of the composition of the materials used to paint historical objects or artifacts iscrucial for the museums, in order to make informed decisions related to their storage, exhibition andconservation. Scientific techniques such as X-ray fluorescence spectroscopy (XRF) and Ramanspectroscopy are routinely employed to analyze and identify the materials used in the construction anddecoration of the culturally significant artifacts. Most major museums around the world, such as theMetropolitan Museum of Art, NYC, have indeed their own equipment in-house. However, every singletechnique by its own has certain limitations and shortcomings. For example a hand-held XRF cannotdetect chemical elements with atomic mass unit less than 8amu. In addition, these techniques non-selectively detect all types of a given element. In other words, they fail to distinguish chemical variationsbased on their oxidation state.In the current presentation, we present the results of X-ray photoemission spectroscopy (XPS), Ramanspectroscopy and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) onan funerary mask and parts of cartonnage of an Egyptian mummy (3rd century BC, approximately). Thecombined results of these three techniques facilitate, in high degree of certainty, identification of thematerials and minerals that have been used to create the painting on these objects. The samples wereprovided by the Museum of Natural Sciences of La Plata. Our preliminary results show that the red colorused for the decoration can be attributed to cinnabar, HgS. The detection of sulfur and arsenic in theyellow and orange part of the cartonnage samples can be attributed to minerals such as pararejalgar, AsSor orpiment, As2S3. The detection of chlorine and copper in the blue / green part of the samples can beexplained by considering the degradation of Egyptian blue to an isomer of trihydroxychloride Cu2(OH)3Cl.In addition, XPS spectra obtained from the gilded part of the mask identified an alloy of gold ( ̴70%) andsilver ( ̴30%) that has been used on the face of the mask.