ELECTROCHEMISTRY AND AUTHENTICATION OF ARCHAEOLOGICAL LEAD USING VOLTAMMETRY OF MICROPARTICLES: APPLICATION TO THE TOSSAL DE SANT MIQUEL IBERIAN PLATE

An essentially non‐invasive electrochemical methodology addressed to the authentication of archaeological lead is described. The method is based on the record of the voltammetric response of nanosamples from the archaeological artefact mechanically transferred to a graphite ‘pencil’ electrode in contact with aqueous buffers. Three diagnostic criteria for authentication are described based on the appearance of: (i) oxidative dissolution signals for trace metals like copper, arsenic, antimony and, often, tin and silver accompanying stripping peaks for lead, (ii) peak potential shifts for reduction peaks for patination products, and (iii) the presence of reduction peaks for PbO₂. The method is applied to the authentication of an Iberian lead plate from the Tossal de Sant Miquel (Llíria, Spain) site using a series of genuine and false pieces from different provenances in the Valencian region (Spain).     

FROM RAW IRON TO SEMI‐PRODUCT: QUALITY AND CIRCULATION OF MATERIALS DURING THE IRON AGE IN FRANCE*

Iron raw materials provide a privileged source of information for the reconstruction of metallurgical techniques and the circulation of iron products. An interdisciplinary approach, combining archaeological and archaeometrical studies of the exemplars known from the French Iron Age, has been undertaken. This enables a new typological classification to be produced that demonstrates a correlation between morphological and structural properties. Through comparison with chronological data, it is possible to propose a reconstruction of the organization of production according to three main periods, which are characterized by the circulation of different qualities of iron and by diverse levels of artisanal specialization.     

CHARACTERIZATION OF NATURAL PRODUCTS ON NATIVE AMERICAN ARCHAEOLOGICAL AND ETHNOGRAPHIC MATERIALS FROM THE GREAT BASIN REGION,U.S.A.: A PRELIMINARY STUDY

Although documentary evidence provided by ethnographers makes reference to the source of adhesives, sealants, dyestuffs and medicines used by the communities of the Great Basin, much of it is sporadic and unspecified. However, observations of amorphous deposits surviving on stone tools, ceramics, basketry and wooden artefacts have prompted an investigation of their identity, procurement and use. The aim initially is to study samples from a number of archaeological and ethnographic contexts from the region. Comparative material includes higher plant and insect resins. The study provides a unique opportunity to document use patterns in plant and animal resources in the Great Basin region.     

The production and technology of glazed ceramics from the middle ages,found in the saepinum territory (Italy): a multimethodic approach*

A collection of ceramics from the Middle Ages found in Altilia and Terravecchia (the Saepinum area, Campobasso, Italy) were characterized by using different mineralogical analyses to investigate their provenance and production techniques. The body ceramic was investigated using Rietveld phase analysis of X‐ray powder diffraction patterns, X‐ray fluorescence spectrometry and scanning electron microscopy. The chemical compositions of the coatings were measured by scanning electron microscopy and their mineralogical compositions were determined using a particular technique of X‐ray small‐angle scattering (SAS) optimized for studies of thin films. Moreover, the material used for decoration was studied using micro‐Raman spectroscopy. The archaeometric results confirmed the distinction into two different ceramic classes, already individuated from archaeological analysis: the Altilia objects belong to the protomajolica class, whereas the objects from Terravecchia are RMR (ramina‐manganese‐red) ceramics. A comparison between the chemical and mineralogical compositions of good‐quality ceramic objects and those of waste products indicated local production of the ceramics. A sharp distinction was found in the chemical composition of the coatings: the Altilia products have tin‐opacified lead glazes, while the Terravecchia ones have transparent high‐lead glazes. Among the Altilia products, the unsuccessful process that produced a large quantity of discarded materials was attributed to the high lead content of the glazes. In fact, the principal advantage of the high lead content was to make the preparation and application of the glaze suspension easier, but the risk of reduction of lead oxide to metallic lead was greatly increased. Using micro‐Raman spectroscopy, the following minerals were identified as pigments: pyrolusite for the dark colour, malachite for green, lepidocrocite for yellow and hematite for red.     

EXPERIMENTAL EVIDENCE FOR THE PROCESSING OF MARINE ANIMAL PRODUCTS AND OTHER COMMODITIES CONTAINING POLYUNSATURATED FATTY ACIDS IN POTTERY VESSELS*

ω‐(o‐Alkylphenyl)alkanoic acids are known to form in vitro from triunsaturated fatty acids following protracted heating. These compounds have recently been identified in absorbed lipid extracts obtained from archaeological pottery vessels, providing a potentially valuable new class of indicator for the processing of commodities, such as marine oils, which contain high abundances of polyunsaturated fatty acids. Experiments were conducted to assess whether ω‐(o‐alkylphenyl)alkanoic acids form when pure compounds and complex triacylglycerol mixtures are heated with a fired clay. The results demonstrate that ω‐(o‐alkylphenyl)alkanoic acids are only produced following heating of unsaturated fatty acids (tri‐, di‐ and monounsaturated species) or complex unsaturated fatty acyl lipids at around 270°C. Heating saturated fatty acyl lipids does not yield ω‐(o‐alkylphenyl)alkanoic acids. Thus, when searching for evidence for the processing of marine derived animal fats in archaeological pottery vessels, it is essential that: ω‐(o‐alkylphenyl)alkanoic acids of carbon length C₁₈ and C₂₀ should be present, ideally with C₂₂ also detectable (if only in trace abundances), together with at least one of the three isoprenoid fatty acids (phytanic, pristanic or 4,8,12‐tetramethyltridecanoic acid).