In the past week, the first radiocarbon dates within the CRUMBEL project have been obtained at the Radiocarbon Dating Laboratory of the Royal Institute for Cultural Heritage in Brussels (IRPA/KIK).
Priority was given to Walloon sites due to the lower number of dated cemeteries, as detected in the archaeological literature. Diaphysis from only white pieces of long bones were chosen because of their thickness and lower porosity. Black and grey bones were avoided, due to problems related to carbon substitution.
The sample pre-treatment has been carried out by Giacomo Capuzzo, Gaia Ligovich and Tess Van Den Brande, under the supervision of Mathieu Boudin, director of the Radiocarbon Dating Laboratory. The bone surface has been removed by acid treatment (HCl) as the surface is less protected against carbon substitution. Then the samples were grinded and left 24 hours in 1% acetic acid to remove secondary carbonates before being washed with demineralized water and dried.
The reaction with phosphoric acid has allowed capturing the released CO2, which has been combusted with silver (Ag) and copper oxide (CuO). The CO2 was then cryogenically trapped and converted to graphite at 680°C using pre-treated Iron (Fe) as catalyst. Finally, the 14C dates were measured on the AMS (type MICADAS: mini carbon dating system) at the IRPA/KIK.
The obtained radiocarbon dates have shown some unexpected results… stay tuned!