Abstract
Bones are mainly composite materials of equivalent volume fractions of mineral (apatite) and organic (collagen) parts. Their infrared spectroscopic characteristics mirror their composition. Bone diagenesis is the post-depositional changes of calcified tissues by chemical degradation. It is a complicated process and affected by numerous external and individual factors. Diagenetic trajectories have been employed using Fourier transform infrared (FTIR) spectroscopy to monitor the preservation status of bioapatite. We studied the diagenesis in ancient Egyptian bones of four dynasties collected from two different locations – Sakkara and Aswan using attenuated total reflectance (ATR) FTIR microspectroscopy. Despite the latter is a promising technique since it is a minimally destructive tool, the samples’ physical properties may affect the data accuracy. The studied bone pieces were from two sites, the shaft and the femur head. Transmission electron microscopy (TEM) was used to investigate the bone crystals size and shape. ATR-FTIR spectrographs showed different molecular fingerprints between Sakkara and Aswan soil samples. The technique was able to monitor different molecular structures across the shaft bones indicating different diagenetic grades. TEM micrographs showed low abundant crystals of needle shaped for Late period shaft bones, while those from Roman Greek period were characterized with abundant irregular thin platelet crystals.