Raman spectroscopic analysis of ancient Egyptian pigments

The application of FT-Raman spectroscopy and visible Roman microscopy to the non-destructive analysis of pigment specimens excavated from Tell el Amarna by Flinders Petrie in the 1890s has provided information about the chemical composition of the materials used by XVIIIth Dynasty artists in the New Kingdom at the time of King Akhenaten, c. 1340 BC. Comparison of the Roman spectra of the samples labelled 'red and yellow ochre ' with documented, archival material from geological collections provided a clear indication of the materials used in the iron(III) oxide/hydroxide system, including α-hematite, goethite, maghemite, magnetite and lepidocrocite. The yellow-orange specimen labelled 'realgar' proved to be a mixture of realgar and pararealgar; since the specimen had been sheltered from light since its excavation, this could indicate that the ancient Egyptian artists recognized the colour variation and may have used this to effect in their decorations. A specimen of yellow ochre contained goethite, α-FeO.OH, with particles of crystalline, highly ordered graphite; in contrast, the red ochre specimens contained amorphous carbon particles.