Investigating beads from Chalcolithic funerary cremation contexts of Perdigões, Portugal

Chemical results show that they have high contents of calcium, and that the surface is more contaminated with soil particles due to high Si, Fe and K contents, and phosphorous was found in higher proportion, certainly originated from the bones. FTIR patterns show that the major part of the beads is calcium carbonate crystallized in calcite form, contaminated with silicates and calcium phosphate, pointing to shells as raw materials. The ToF-ND results also indicate the crystal lattice structure of calcite, and aragonite, a polymorph formed in the biomineralisation process of shells, was not detected, indicating a total phase transformation to calcite probably due to heating processes during funerary practices. The SEM-EDS results confirm the shell nature of beads. The results were of wider significance for the archaeological discussion, especially deciphering the nature of the beads, contributing to the debate of interaction in the Chalcolithic of Southern Iberia.