Using spinel chemistry to characterise archaeological steatite found in the wall paintings of Tell el-Dab(c)a, Egypt

摘要

In the Aegean-type wall paintings of Tell el-Dab(c)a, Egypt, steatite was used as a constituent of the white colour. Previous research has revealed that the use of talc as a pigment can be considered as an important marker of Aegean craft traditions. In this case study it is therefore of primary importance to trace back the origin of this particular mineral and rock, especially since it can be found in several locations in the Mediterranean including Egypt, Crete and Cyprus. While there is still no generally valid strategy to assign archaeological objects made from this particular material to a specific steatite deposit, the physio-chemical characterisation of the latter mostly relies on the measurement of Rare Earth Elements (REE's) or other methods focusing on the chemical composition of the whole rock. In this paper, a new way to determine steatite origin is presented using electron microprobe characterisation of spinels inside the steatite matrix. Those tracer minerals can not only be the source of information concerning the formation of steatite but their core composition can in some cases also reflect the primary composition of the precursor ultramafic rock. This method focuses on the geotectonical history and genesis of the protolith rather than on steatite's chemical composition. The results reveal the spinels to have similar characteristics to those of supra-subduction ophiolites in the Egyptian Central Eastern Desert. We suggest a correlation between gold and steatite exploitation and thus the use of local raw materials for the creation of the Aegean-type paintings.