BUILDING A BRIDGE TO THE PAST: ARCHAEOMETRY AT THE IPEN REACTOR

Neutron activation analysis has contributed to research in Peru in different scientific fields, particularly in archaeometry. In archaeometry, applications include the characterization of copper alloy artefacts from the tomb of El Señor de Sican to determine production methods, ceramics from the Wari Culture to study production, and distribution of Middle Horizon pottery in Cuzco, ceramics from Villa El Salvador to determine production groups, and obsidian source analysis.     

LEAD ISOTOPE AND TRACE ELEMENT ANALYSIS IN THE STUDY OF OVER A HUNDRED SOUTH INDIAN METAL ICONS*

Technical investigations were made on 130 South Indian statuary images and a few miscellaneous artefacts mostly sampled from the Government Museum, Madras, India, and from the Victoria and Albert Museum and the British Museum, UK. Lead isotope investigations were attempted on 60 of these, and compositional analysis for 18 elements on 115, using inductively coupled plasma optical emission spectroscopy; thus, for 40 objects both lead isotope and trace element analysis was done. From the isotopic and elemental framework, insights are obtained into some art-historical problems of images and artefacts of the Pre-Pallava, Pallava, Chola (i.e., Vijayalaya Chola), Later Chola (i.e., Chalukya-Chola and Later Pandya), Vijayanagara (and Early Nayaka) and Later Nayaka (and Maratha) dynasties, spanning the Early Christian era to the nineteenth century, along with a few other regional styles. Inferences are also made regarding provenance of the lead and the early use of zinc and brass in the early historic period (c. fourth century BC—fourth century AD).     

THE ELEMENTAL COMPOSITION OF BENIN MEMORIAL HEADS*

Among the Nigerian cast copper‐alloy artefacts, the chronology of the Benin memorial heads has been the most fully worked out. Therefore, a study focused upon their elemental compositions is particularly likely to be interpretable in terms of development of the alloys used in their making. The elemental analyses, both published and unpublished, of 66 Benin heads, supplemented with seven analyses of some artefacts excavated from a well‐dated, very early Benin site, have been collected, analysed statistically and computed to the elemental analyses of 11 heads and figures from Udo. All but a very few of the Benin heads and artefacts separate into five compositional groups, indicating a chronological sequence of different alloying traditions. All but one of the Udo objects fall into a distinctly separate compositional group, together with two Medicine heads. The compositional groups correlate remarkably well with the stylistic types proposed by Dark.     

A PRELIMINARY PETROGRAPHIC ANALYSIS OF CYPRIOT WHITE SLIP II WARE*

Samples of Late Bronze Age White Slip II ware from Cyprus were analysed using optical and scanning electron microscopy in conjunction with energy and wavelength dispersive analyse The slip has a novel granular nature and the coarser aggregates are impressed into the outer surface of the body, indicating that it was applied to a moist surface before the vessels were fired. It has a consistent mineral assemblage (Mg‐chlorite + illite‐smectite + sphene + anatase/rutile ± albite) which is very similar to that of hydrothermally altered zones associated with copper orebodies in the Troodos Massif which were mined in antiquity Our analysis suggests that the raw material for the slip was not found at the ground surface, because the alteration assemblage is unaffected by oxidation and copper carbonate or iron staining. It may, therefore, be a by‐product of sub‐surface ore extraction     

THE EFFECTS OF CORROSION AND CONSERVATION TREATMENTS ON NON‐DESTRUCTIVE NEUTRON DIFFRACTION ANALYSIS OF ARCHAEOLOGICAL COPPER ALLOYS: PRELIMINARY RESULTS*

Analysis of residual stress in archaeological copper alloy artefacts by neutron diffraction has considerable potential for the investigation of early fabrication processes. However, residual stresses in metals are known to relax due to conditions similar to those encountered during burial, corrosion and conservation. In this pilot study, we investigate the effects of corrosion and conservation on a small group of replica copper ingots. Although corrosion and light cleaning do indeed cause some relaxation of stresses in the metal, corrosion having the most significant effect, the basic patterns and major features of the stress profiles may still be seen.     

MINERALOGICAL AND PETROLOGICAL INVESTIGATIONS OF EARLY BRONZE AGE COPPER‐SMELTING REMAINS FROM THE KIECHLBERG (TYROL,AUSTRIA)

The prehistoric settlement on the Kiechlberg hilltop is located a few kilometres to the north‐east of Innsbruck, in the Tyrolean Inn Valley. Despite its rather isolated location, a multiphase settlement between the fifth and the second millennium bc was confirmed by archaeological investigations in 2007 and 2008. Metallurgical artefacts, such as copper ore fragments, copper slag and raw copper, as well as finished copper and bronze artefacts, are concentrated mainly in Late Copper Age to Middle Bronze Age layers. The chemical compositions of the slag and raw metals confirm Fe—Zn tetrahedrite–tennantite (fahlore) smelting. The ore was most probably imported from the 30–50 km distant copper ore deposits (mainly fahlore) of Schwaz–Brixlegg, in the Lower Inn Valley. The small amount of slag and the presence of slagged and thermally altered ceramic fragments suggest copper production in small‐scale workshops. Most probably, sulphide‐rich ores were smelted in crucibles in a hearth fire. The process was relatively reducing below the 2Sb + 1.5O₂ → Sb₂O₃ reaction (?8.5 log fO₂ at 1100°C), producing Sb‐rich (>10 wt% Sb in metal) raw copper. Inhomogeneous slag remains containing high amounts of sulphide and metal inclusions suggest a poor separation of the metal, matte (copper sulphide) and silicate/oxide melt during the smelting process.     

The Pottery of Khirbet En-Nahas: A Rejoinder

Abstract

Smith and Levy (2008) have published an assemblage of pottery from the copper production centre of Khirbet en-Nahas in Jordan. Based on their interpretation of the ¹⁴C dates from the site and contra the accumulated knowledge on the ceramic typology of the Levant they argue that this pottery dates to the Iron I and Iron IIA, and that there was no later activity at the site. We show that much of the Khirbet en-Nahas pottery dates to the Iron IIB–C. We argue that the charcoal samples sent for radiocarbon dating originated from the waste of industrial activity at the site in the Iron I and Iron IIA, while the pottery came from a post-production activity in the Iron IIB–C — an activity that included the construction of a fort on the surface of the site. We propose that the fort was built along the Assyrian Arabian trade route, at the foot of the ascent from the Arabah to the Assyrian headquarters of Buseirah.     

SERIPHOS SURFACES: A STUDY OF COPPER SLAG HEAPS AND COPPER SOURCES IN THE CONTEXT OF EARLY BRONZE AGE AEGEAN METAL PRODUCTION

Kephala and Phournoi, on the island of Seriphos, add to a growing number of EBA metal production sites identified in the south‐central Aegean. Analytical examination of samples from the two sites addressed the technological parameters of the copper smelting process, indicating the use of mixed oxidic and sulphidic copper–iron ores to produce unalloyed copper with minute copper sulphide inclusions. A preliminary geological reconnaissance of the island identified several small copper mineralizations, one of them close to the site of Kephala. Nevertheless, the ore sources used remain unclear. Comparisons are made with other contemporaneous neighbouring smelting sites.     

SHAFT‐HOLE AXES FROM SLOVENIA AND NORTH‐WESTERN CROATIA: A FIRST ARCHAEOMETRIC STUDY ON ARTEFACTS MANUFACTURED FROM META‐DOLERITES*

A group of Copper Age shaft‐hole axes from Caput Adriae (northeastern Italy, western Slovenia and northwestern Croatia) manufactured using meta‐dolerite have been analysed for major and trace elements. All the samples show magmatic textures and well recognizable relicts of primary mineralogical phases. Petrographic observations suggest an ophiolitic provenance of the protolithic source(s) while geochemical data indicate that the original magmas originated in a fore arc or pre arc tectonic setting. Strong similarity has been found with several lithotypes from the Banija Ophiolite Complex (Croatia), here indicated as the most probable source area. Considering the available archaeometric data about shaft‐hole axes found in northern Italy and Caput Adriae in comparison to those of axe blades discovered in the same area, it emerges that there is a utilization of different rock types, the source of which appears to be quite close to the discovery sites. In the investigated area the shaft‐hole axes are largely made from ophiolitic‐related rocks which are associated with copper deposits. Consequently there may have been a relation between the localization of the geological sources of shaft‐hole axes and the development of metallurgical activities.     

LA–ICP–MS,SEM–EDS AND EPMA ANALYSIS OF EASTERN NORTH AMERICAN COPPER‐BASED ARTEFACTS: IMPACT OF CORROSION AND HETEROGENEITY ON THE RELIABILITY OF THE LA–ICP–MS COMPOSITIONAL RESULTS*

This study discusses the relevance of compositions obtained using laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) for the purpose of identifying the provenance of copper‐based artefacts found in Virginia at Native American sites dated from the 16th to the 18th centuries. Ten artefacts were investigated by scanning electron microscopy – energy dispersive spectrometry (SEM–EDS) to visualize the corrosion and characterize the heterogeneities in the metal and electron probe micro‐analysis (EPMA) to determine separately the compositions of the intact metal and of the corrosion product. It is shown that the corroded surfaces are highly depleted in zinc but that representative concentrations can be determined by sampling the deeper, uncorroded metal. In contrast, lead values are highly variable because of the heterogeneous distribution of this metal within the bulk copper. Despite these problems, brass is easily identifiable and American native copper and European smelted copper can be unambiguously distinguished with LA–ICP–MS on unprepared artefacts using As, Ag, Ni and Sb trace elements.