Diagnosis of archaeological bones: Analyzing state of conservation lower Pleistocene bones through diagenesis methods

Initial physicochemical assessment of cultural materials plays a critical role in the research and management of cultural heritage, serving as a foundation to comprehend deterioration mechanisms and develop effective conservation treatments. However, this knowledge is more advanced in several cultural material such as artwork or historic building, than in bone and fossils. This study focuses on bone material conservation, applying diagenetic methods for characterizing and assessing the state of conservation of archaeological bones from Pit 1 at Barranc de la Boella (BB), an open-air archaeological site from the late Early Pleistocene, from a conservation perspective. Microstructural analyses, including mercury intrusion porosimetry (MIP) and histological analysis, alongside microchemical analyses through Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), and FTIR with KBr pellets and X-Ray Diffraction (XRD), were conducted to evaluate the decay processes affecting the bones. Results indicated poor bone preservation characterized by high porosity, significant microbial attack, collagen degradation, and the potential recrystallization of bioapatite into fluorapatite. These findings underscore the substantial challenges posed by open-site conditions to preservation efforts and highlight the need for suitable conservation treatments, such as consolidation to reinforce the microstructure. The study emphasizes the importance of characterizing archaeological bones to understand the factors influencing their preservation states and guide conservation works in this material. This work contributes to the knowledge of diagenesis studies to standardize the diagnosis of the state of conservation on archaeological bones.