This paper illustrates a case study related to the characterisation of corrosion products present on recently excavated artefacts. The archaeological findings, from the Rakafot 54 site (Beer-Sheva, Israel), consist of 23 coins and a pendant, all dating back to the Roman period. Raman spectroscopy was used to identify the corrosion products that compose the patina covering the objects. To facilitate and support their identification, spectra were then processed using principal components analysis. This chemometric technique allowed the identification of two main compounds, classified as atacamite and clinoatacamite, which formed the main components of the patinas. The results of this investigation can help in assessing the conservation state of artefacts and defining the correct restoration strategy.
22 February 2023 in Archaeological and Anthropological Sciences
Apart from mould and core remnants attached to metal objects from the Chalcolithic Southern Levant (ca. 4500–3800 BCE), production remains of early lost wax casting are seemingly invisible in the archaeological record. An experiment using reproduced casting moulds was performed to simulate the Chalcolithic processes to investigate whether the moulds might have deteriorated to an unrecognisable state after the casting process. Results from previous studies on mould remains attached to metal objects were complemented with ethnographical accounts for the experimental set-up. The moulds were prepared from local clays already in use during the Chalcolithic. Petrography, simple alteration tests, and general technological considerations reveal that preservation may be poor but is still visible to the naked eye. The preservation of multi-layered fragments is crucial, despite their friable or brittle state after casting. A further, previously unmentioned, clear indication of lost wax casting moulds may be the combination of vegetal temper with mineral/rock temper in their clay paste. This composition derives purely from technological considerations and is independent of depositional and post-depositional processes.
Apart from many lost wax cast metal fragments, crucible fragments and several heated sediment nodules were found at the Chalcolithic site Fazael 2 (central Jordan Valley). Petrographic investigations on the heated sediment nodules revealed many features characteristic of the Chalcolithic Southern Levantine lost wax casting moulds. Heating temperatures were assessed using infrared spectroscopy, showing that casting did not vitrify the clay fraction in the moulds. Consequently, Fazael is the first identified Chalcolithic Southern Levant production site for lost wax cast metal items. These findings confirm the existence of a metallurgical tradition with lost wax casting in the Jordan Valley parallel to the unalloyed copper metallurgy in the Northern Negev. Moreover, crucibles and heated sediment nodules are made of local ferruginous loess, a material not mentioned in previous studies on lost wax casting mould fragments. Therefore, the existence of more than one such production site must be assumed.
This paper presents the results of a petrographic study conducted on a selection of 88 Cypriot ceramic Neolithic vessels, originating at seven sites, representing various geographic regions on the island. The study is aimed at determining their place of origin and disclosing details about the technology of their production. All the vessels studied were found to be locally made on the island. There are, however, indications that there was restricted movement of ceramic vessels within defined regions of the island. In addition, a clear distinction between the production technologies of coarse ware and painted ware was observed, reflecting island-wide shared technological traditions. However, even within these seemingly uniform technological traditions, regional variations can be observed. These observations support previous interpretations suggesting a division between ‘northern’ and ‘southern’ social groups on the island during the Ceramic Neolithic period.
Excavations at the Chalcolithic site Fazael in the central Jordan Valley uncovered a large number of metal items, many of them polymetallic copper alloys cast in the lost wax technique. Metallography and SEM–EDS analysis on a subset of the assemblage confirm previous notions of the lost wax metallurgy in the Chalcolithic Southern Levant but extend them significantly in three aspects: The Fazael metal assemblage is slightly depleted in its arsenic content compared to metal assemblages from other sites, silt-sized quartz inclusions in unalloyed and polymetallic copper items, and the presence of unalloyed copper inclusions. These latter provide the earliest direct evidence for mixing of different metal types in West Asia, potentially alloying or recycling.