A mummy's secrets: Serendipity, Computed Tomography and non-invasive x-ray diffraction

Contents of a Roman-era Egyptian mummy (Hawara portrait mummy 4, HPM4) were investigated by clinical Computed Tomography (CT) and position-resolved, high-energy, microbeam x-ray diffraction at the Advanced Photon Source (APS). The combined techniques provide a more complete picture of the mummy than either could alone. From CT, the person within the mummy was about five years old at death, there was no evidence of skeletal trauma and the team inferred female biological sex. Other foci of the CT investigation were moderate absorption shards within the skull cavity, identified as resin; the layers of linen wrapping the mummy, in particular one layer which appeared to be heavily impregnated with bitumen or pitch; wires (specimen pins) apparently added during earlier restorations of HPM4 and a large, high attenuation inclusion located in the wrappings above the abdomen. The CT data also provided a 3D roadmap guiding the diffraction experiments, the first of their kind performed in situ on an intact mummy. A ray tracing technique was developed to identify where along the x-ray beam path diffraction signals originated, and in all of the cases, precision were 1-2 mm. Further, the diffraction origins matched positions of these features in the CT scan. Diffraction identified the wires as modern dual phase steel matching that of a reference specimen pin and the inclusion above the abdomen as calcite, possibly a carved scarab. The cross-sections of the skull and of the femora were mapped accurately with the technique, but the desire to minimize potential beam damage to HPM4 dictated that very short integration times were used and the signal to noise ratio was too low for detailed analysis of the bone diffraction patterns. The CT plus diffraction approach to studying the contents of mummies adds very important information, but the logistics of transporting a mummy first to a CT scanner and then to a synchrotron radiation source mean that the approach will probably only be used to solve key mysteries.

Automated summary

The contents of a Roman-era Egyptian mummy were investigated using clinical CT and high-energy microbeam x-ray diffraction techniques, providing a more complete picture of the mummy's composition and structure. The study revealed the age, sex, and various features of the mummy, including wires, resin shards, and a calcite inclusion. While the combined CT and diffraction approach offers valuable insights, logistical challenges may limit its application to solving key mysteries in the future.