This work aimed to characterize the deportment/concentration and liberation/association of the metals and light elements within mechanically processed waste printed circuit boards (PCBs) that hold the complex and heterogeneous structure and distribution of different material components. Waste PCBs passed through a series of mechanical processing (i.e., comminution and sieving) for metal recovery and were then characterized without further destroying the particles in order to capture their heterogeneity. The characterizations were performed in a laboratory and large-scale neutron facility. The results obtained with a portable X-ray fluorescence spectroscopy and prompt gamma activation analysis were compared and confirmed the good agreement and complementarities in general. The advantages and disadvantages of the two different methods were identified and discussed in this paper, in relation to their application to the analysis of mechanically processed PCB particles.

Haltern 70 amphorae sherds from Castro do Vieito, a Roman settlement from the NW of Portugal occupied during the early imperial period, were studied by Mössbauer spectroscopy at room temperature and 4.2 K, XRD, and XRF, aiming to understand the firing conditions of their production. Firing in air at 750 and 800 °C were performed in a sherd that was carefully studied. Also, a handle with part of the neck attached and with the potter’s stamp “LH …” was studied. In general, it can be deduced that the amphorae were fired under reducing conditions between 800 and 950 °C, having been subjected to an oxidation process only when already cooling. It was also inferred that the provenance of all the Haltern 70 amphorae found in Castro do Vieito is probably the same and that the stamped amphora also seems to come from the same locality.

Roman amphorae are among the most frequently excavated archaeological ceramics and provide valuable information on ancient manufacturing techniques and trade networks. This work presents a comparative Mössbauer spectroscopy study of amphora sherds recovered from kiln sites in the Roman provinces of Hispania Lusitania and Baetica in order to reconstruct firing procedures and assess the influence of raw material composition on ceramic appearance and iron speciation. Three representative samples—São Lourenço (Lusitania), Lebrija (Baetica), and Arva (Baetica)—were investigated by ⁵⁷Fe Mössbauer spectroscopy at room temperature and 4.2 K, complemented by X-ray diffraction (XRD), X-ray fluorescence (XRF), and controlled laboratory re-firing experiments under reducing and oxidising atmospheres. The Mössbauer results reveal that all studied amphorae were originally fired under variable redox conditions, involving a reducing stage followed by partial oxidation during the final stages of firing and cooling. Re-firing experiments reproduced the original spectra and demonstrated that the observed iron phase assemblages reflect primary technological processes rather than post-depositional alteration. Low-calcium ceramics developed abundant hematite and characteristic red colours after oxidation, whereas calcium-rich ceramics favoured incorporation of iron into gehlenite and vitreous phases, producing buff or grey colouration. The Arva samples further illustrate how incomplete oxygen penetration generated red oxidised surfaces surrounding partially reduced cores. These results demonstrate that Roman amphora production at the kiln sites studied relied on empirically controlled firing regimes in open updraught kilns and that calcium content was a major factor governing both iron mineralogy and final ceramic appearance.