Archaeometallurgical characterization of the earliest European metal helmets.

Archaeometric analyses on conical and decorated cap helmets from the Bronze Age are presented. The helmets are dated to the 14-12th century BC according to associated finds in hoards. Alloy composition, material structure and manufacturing processes are determined and shed light on the earliest development of weaponry production in Central and Eastern Europe. Analyses were carried out using light and dark field microscopy, SEM-EDXS, PIXE, TOF-ND and PGAA. The results allowed reconstructing the manufacturing process, the differences between the cap of the helmets and their knobs (i.e. alloy composition) and the joining technique of the two parts.

Electrochemical Approximation to Bronze Age Chronology via Multiple Scan Voltammetry.

Insert A multiple-scan voltammetry strategy is described and applied to a set of 107 Bronze Age and later copper/bronze objects, mainly from sites in Central Europe. This methodology allows the study of the compositional and textural properties (compactness, crystallinity, degree of hydration) of the patina to be studied from the accumulated peak current values for the characteristic signals corresponding to the reduction of cuprite and tenorite to metallic copper. A new model for the relationship between peak current and the depth reached in successive scans is presented and used to discriminate samples of different provenance and manufacturing technique, as well as their ascription to different Bronze Age periods.

Multidisciplinary analyses on the 11th-12th century bronze doors of San Marco, Venice.

Two 11th- and 12th-century entrance doors from the Basilica di San Marco in Venice, made of different copper alloys and woods, were non-invasively examined in situ. The chemical composition of the metals, the way in which different metal parts were joined together, the tree species used to construct the supporting structures and the age of the wood are determined. A portable ED-XRF instrument and optical microscopes were used. The doors were also photographed to produce high-resolution orthophotos and 3D models. The metal parts of the doors were made of leaded tin-bronze and quaternary Cu-Sn-Zn-Pb alloys and were mounted on a wooden multi-layer structure of larch and silver fir; the dendrochronological dates of some of the larch boards are 1965, teminus post quem.

Cu3As: Uncommon Crystallographic Features, Low-Temperature Phase Transitions, Thermodynamic and Physical Properties.

The formation and crystal structure of the binary Cu3As phase have been re-investigated. Some physical properties were then measured on both single crystal and polycrystalline bulk. Cu3As melts congruently at 835 °C. At room temperature (RT), this compound has been found to crystallize in the hexagonal Cu3P prototype (hP24, P63cm) with lattice parameters: a = 7.1393(1) Å and c = 7.3113(1) Å, rather than in the anti HoH3-type (hP24, P-3c1) as indicated in literature. A small compositional range of 74.0-75.5 at.% Cu (26.0-24.5 at.% As) was found for samples synthesized at 300 and 400 °C; a corresponding slight understoichiometry is found in one out of the four Cu atomic sites, leading to the final refined composition Cu2.882(1)As. The present results disprove a change in the crystal structure above RT actually reported in the phase diagram (from γ' to γ on heating). Instead, below RT, at T = 243 K (-30 °C), a first-order structural transition to a trigonal low-temperature superstructure, LT-Cu3-xAs (hP72, P-3c1) has been found. The LT polymorph is metrically related to the RT one, having the c lattice parameter three times larger: a = 7.110(2) Å and c = 21.879(4) Å. Both the high- and low-temperature polymorphs are characterized by the presence of a tridimensional (3D) uncommon and rigid Cu sublattice of the lonsdaleite type (Cu atoms tetrahedrally bonded), which remains almost unaffected by the structural change(s), and characteristic layers of triangular 'Cu3As'-units (each hosting one As atom at the center, interconnected each other by sharing the three vertices). The first-order transition is then followed by an additional structural change when lowering the temperature, which induces doubling of also the lattice parameter a. Differential scanning calorimetry nicely detects the first low-temperature structural change occurring at T = 243 K, with an associated enthalpy difference, ΔH(TR), of approximately 2 J/g (0.53 kJ/mol). Low-temperature electrical resistivity shows a typical metallic behavior; clear anomalies are detected in correspondence to the solid-state transformations. The Seebeck coefficient, measured as a function of temperature, highlights a conduction of n-type. The temperature dependence of the magnetic susceptibility displays an overall constant diamagnetic response.

Work on the cutting edge: metallographic investigation of Late Bronze Age tools in southeastern Lower Austria.

This paper analyses 20 Late Bronze Age (ca 1080-800 BC) copper alloy objects to discern their manufacture and the skills of local craftsmen. Several tools and jewellery were studied that originated from a bronze workshop located immediately next to the Prigglitz-Gasteil copper ore mining site and several contemporaneous sites in the surrounding area. The samples were studied with optical microscopy (microstructurally), and SEM-EDXS and XRF (chemical analyses). Our analyses are part of a larger study and suggest that the Prigglitz region's bronze production was not standardized. Particular alloys do not seem to have been chosen for object types or due to their intended use-function. Notably, approximately 20% of the objects contain unalloyed copper inclusions, which are most likely a result of the incomplete mixing of scrap metals and alloys during their production.

Melting, smelting, and recycling: A regional study around the Late Bronze Age mining site of Prigglitz-Gasteil, Lower Austria.

This paper presents a study on copper production and distribution in Lower Austria's southeastern region during the Late Bronze Age (c. 1350-800 BC), with the focal point being the chemistry and isotopic character of artifacts from a small copper mining site at Prigglitz-Gasteil on the Eastern Alps' easternmost fringe. Ores, casting cakes, and select objects from the Late Bronze Age mining site at Prigglitz-Gasteil, Lower-Austria, and within 15 km of its surroundings, were chemically and isotopically analysed using XRF, NAA, and MC-ICPMS. The importance of Prigglitz-Gasteil as a local mining and metal processing center is evaluated based on the produced data, and the distribution and sourcing of copper-producing materials found at the site are discussed. Special attention is paid to the mixing of scrap and source materials early in the metal production process. The most salient discussions focus on the variability of the chemistry and Pb isotopic ratios of the studied objects, which seem to constitute a multitude of source materials, unlike the pure chalcopyrite-source copper produced from the Prigglitz-Gasteil mine itself. The analytical data suggests that copper alloys were mainly imported from materials originating in the Slovakian Ore Mountains, which were subsequently mixed/recycled with relatively pure locally produced copper. The purity of the copper from Prigglitz-Gasteil was fortuitous in identifying imported copper that contained measurable amounts of Pb and other chemically distinct characteristics. The chaîne opératoire of metal production at the site is mentioned; however, it is clear that additional information on the region's geochemistry is required before any finite conclusions on the ore-to-metal production can be made.