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.     

ARCHAEOMAGNETIC DATING OF COPPER SMELTING SITE F2 IN THE TIMNA VALLEY (ISRAEL) AND ITS IMPLICATIONS FOR THE MODELLING OF ANCIENT TECHNOLOGICAL DEVELOPMENTS

Site F2 in the Timna Valley, Israel, is a small copper smelting site of ‘primitive’ technology, dated by its excavator to the Pottery Neolithic (sixth to fifth millennium bce ). This early date challenges the common view of the beginning of smelting technology in the Levant and has been contested by various scholars since its publication. In this study, we present results of archaeointensity experiments conducted on slag fragments from the site. The slag yielded an excellent ancient geomagnetic value (64.1 ± 1.1 μT) that, when compared to the Levantine master curve, suggests an age not older than the second millennium and most probably between the 13th and 11th centuries bce . In addition to demonstrating the applicability of geomagnetic archaeointensity experiments to independent dating of slag, we discuss the implications of the current results for the socio‐historical picture of the Timna Valley, and in particular for the way in which technological developments were previously modelled in the archaeometallurgical research on the region.     

Indigenous African Furnace Types and Slag Composition—Is there a Correlation?

Within variation, three major iron smelting furnaces were used in the Iron Age of sub‐Saharan Africa, ranging from the natural draught driven tall shaft to the forced draught powered low shaft and bowl furnaces. These furnace types are, however, mostly known from the ethnographic context. Often, archaeologists are confronted with remnants from the smelting process, forcing them to speculate on the anatomy of the extant furnaces. The presence of multiple fused tuyeres has been used to identify natural draught furnaces in the archaeological record. However, working back from smelting remains such as slag to the furnace type using physical and chemical evidence has generally proved to be ‘undoable’. Thus, when randomly selected, the chances are high that one cannot separate bowl furnace slags from those that formed in their tall or low shaft counterparts. This observation is hardly unexpected; analogous thermodynamics and thermo‐chemical reactions governed bloomery smelting irrespective of furnace type. Rehren et al. (2007) have labelled this phenomenon the ‘tyranny of system driven constraints’. In this study, we argue that the hierarchical use of statistical methods may add another layer of evidence which, when coupled to archaeological indicators, may be useful in correlating slag chemistry to furnace types used in antiquity.     

Technological Choices in Hand‐Made Indigenous Pottery from Western Mallorca (Balearic Islands,Spain) (C.1200–75 bc): An Archaeometric Approach

This paper addresses the technological choices observed in Mallorca (Spain) for the production of hand‐made pottery during the Late Bronze and Iron Age. We have conducted a diachronic analysis of the ceramic assemblages recovered from two archaeological sites placed in the same territory by means of X‐ray fluorescence and optical microscopy by thin‐section analysis. The archaeometric characterization of the hand‐made vessels allows us to establish several compositional groups related to the use of different raw materials and certain paste recipes associated with the archaeological sites and periods considered. Thus, this study evidences different productive strategies in each site and across time in the same geographical area.     

Microstructural and elemental analyses of slags excavated from Xuxiebian iron‐smelting site,Sichuan, China

Xuxiebian is an iron‐smelting site located in Pujiang county of Sichuan province, China. Two excavations were carried out in 2007 and 2011, and four bowl‐shaped furnaces were excavated. Ten slag samples from the site were prepared and analysed. The present paper reports the results of metallographic and elemental examination of the specimens. It is concluded that both pig‐iron‐smelting and refining process were applied at the Xuxiebian site, and the bowl‐shaped furnaces are possibly refining furnaces. The function of the site was probably to produce pig iron and refine the pig iron into wrought iron.     

TECHNOLOGY AND PROVENANCE OF A COLLECTION OF ISLAMIC COPPER‐BASED OBJECTS AS FOUND BY CHEMICAL AND LEAD ISOTOPE ANALYSIS*

Chemical and lead isotope analyses were utilized to determine the composition, technology and origin of a collection of Islamic copper‐based objects found in Jordan. The atomic absorption spectrometry results show that the objects were made of different types of copper‐base alloys that contain various amounts of zinc, tin and lead. The use of brass, highly leaded brass and quaternary alloys of Cu‐Zn‐Sn‐Pb in the manufacture of everyday, household objects strongly points to Islamic traditions. The lead isotope compositions of the objects match very well that of the copper ore mined from the Dolomite‐Limestone‐Shale unit of the Arabah copper mines.     

Chemical characterisation and manufacturing technology of late Roman to early Byzantine glass from Beit Ras/Capitolias,Northern Jordan

The finding of considerable collections of glass artefacts, together with considerable lumps of glass chunks, fuel ash slag and kiln fragments related to glass processing strongly suggests a local secondary production (working) of glass at the Beit Ras/Capitolias archaeological site in northern Jordan from the late Roman to the early Byzantine period. The chemical analysis of ancient glasses can provide important information regarding the manufacturing technology of the glass made during a specific period. The aim of this study is to characterise the chemical and technological aspects of late Roman to early Byzantine glasses excavated from this main archaeological site. Furthermore, the present paper aims to provide incontrovertible evidence that this site must be considered as a major centre for the secondary production of glass during a period between the 3rd and the 6th centuries. For this purpose, a considerable group of raw glass chunks and vessel fragments of different colours and typologies were collected. The results of chemical analyses indicated that the glass did not show a clear difference in chemical composition between late Roman and early Byzantine times. All the glasses (artefacts and chunks) are of the soda-lime-silica type and correspond to the previously defined Levantine I glass group. The chemical composition of the glass chunks, identical to that of contemporary glass of the same colour, strongly suggests that these chunks were used for the manufacture of late Roman to early Byzantine glass at Beit Ras. The observation of technological features indicates that glass chunks were produced in massive tank furnaces in other primary production centres elsewhere, and were meant for local reworking. According to the microscopic examination, it can also be observed that mould-blowing was the main technique used for forming glass.     

REGIONAL VARIATIONS IN BLOOMERY SMELTING SLAG OF THE IRON AGE AND ROMANO‐BRITISH PERIODS*

This study highlights regional variation in the composition of iron‐smelting slag produced in England prior to the medieval period and attempts to link slag composition to the type of ore smelted. For many sites, the slag compositions were consistent with the use of limonite ore, but there is evidence that siderite ore was smelted at sites in Sussex in the late Iron Age/Romano‐British periods. A compositional comparison of smelting slags and slag inclusions in Iron Age currency bars, using data from Hedges and Salter (1979 ), illustrates the potential of smelting slag compositional data in provenance studies of early iron objects.     

GLASS BY DESIGN? RAW MATERIALS,RECIPES AND COMPOSITIONAL DATA*

Compositional analyses of ancient and historic glasses have often been interpreted in terms of the use of specific raw materials in glass manufacture. However, the known inhomogeneity of many glass‐making raw materials and the insolubilities of some compounds make any explanation of compositional data problematic. This paper looks at three glass‐making alkalis with a view to understanding how the compositions of these raw materials are carried through to the final glass. The chemistry and variability of the raw materials are discussed, as is their contribution to the final glass composition. In addition, the choices and decisions made by glassmakers are acknowledged in the final glass compositions. This combination of factors addresses the complexity of predicting the use of specific raw materials from the finished glass composition.     

COPPER AND BRONZE DURING THE ENEOLITHIC AND EARLY BRONZE AGE: A METALLOGRAPHIC EXAMINATION OF AXES FROM THE NORTHALPINE REGION*

This paper presents the results of a metallographic examination of Eneolithic and Early Bronze Age axes from the Northalpine region of central Europe. During this period, different types of copper were in use: arsenical copper, Fahlerz copper and tin bronze. We examine if and to what extent the different properties of the metals used were known to prehistoric metalworkers and actively manipulated in the production of the axes. The development of methods of casting and smithing is discussed. Both aspects contribute to our understanding of the nature of prehistoric technological change. During the Early Bronze Age of the Northalpine region, different traditions of early metallurgy can be identified, which differ in their use of Fahlerz copper, their attitude towards tin alloying and the use made of tin bronze in the production of the axes. These traditions can only be adequately described by reference to both composition—that is, access to different types of copper as well as tin—and knowledge of the production techniques provided by metallographic data.     

THE ANCIENT MINE OF SERVETTE (SAINT‐MARCEL,VAL D’AOSTA,WESTERN ITALIAN ALPS): A MINERALOGICAL,METALLURGICAL AND CHARCOAL ANALYSIS OF FURNACE SLAGS*

The Cu–Fe mining district of Servette is located in the valley of Saint‐Marcel (Val d’Aosta) at about 1800 m a.s.l. in the western Italian Alps. A large furnace slag deposit occurs near the Servette mine. Slags are mainly constituted by silicate and oxide in a glassy matrix, with disseminated sulphides and iron–copper alloys, and they record temperatures of 1380–1100°C. Radiocarbon dating of slag charcoals has shown that metallurgy in this site took place around ad 890–980. The charcoal analysis has shown that coniferous wood was mainly utilized, and intensive exploitation over the centuries led to a change in the composition of the local woods.     

SCIENTIFIC ANALYSIS OF SEVENTH‐CENTURY GLASS FRAGMENTS FROM THE CRYPTA BALBI IN ROME*

Inductively coupled plasma emission spectroscopy, reflectance spectroscopy and X‐ray diffraction were used to study seventh‐century AD glass fragments from the Crypta Balbi in Rome. All the samples were found to be silica‐soda‐lime glasses. Iron determines the colour of blue‐green, green and yellow‐green transparent glasses; chemical composition suggests deliberate addition of iron and/or manganese in about half the samples. Copper was found as the main colourant in red, pale blue and blue‐green opaque fragments; elemental copper acts as an opacifier in red glass, and calcium antimonate in white, pale blue and blue‐green glasses. Detection of antimony in transparent fragments suggests recycling of opaque mosaic tesserae.     

LEAD ISOTOPE ANALYSIS OF ARCHAEOLOGICAL METALS BY MULTIPLE‐COLLECTOR INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY*

Lead isotope ratios in archaeological silver and copper were determined by MC–ICPMS using laser ablation and bulk dissolution without lead purification. Laser ablation results on high‐lead metals and bulk solution analyses on all samples agree within error of TIMS data, suggesting that problems from isobaric interferences and/or mass bias variations due to the presence of matrix elements are insignificant. Inaccurate laser ablation analyses on low‐lead copper reflect erroneous mass bias corrections from use of a non‐matrix matched standard. However, in most cases, silver and copper are analysable for lead isotopes by bulk dissolution or laser ablation MC–ICPMS with simplified sample preparation.     

Early copper smelting at Itziparátzico,Mexico

Archaeological fieldwork and archaeometallurgical analysis have identified a Late Postclassic regional centre of copper production in western Mexico. The total output from a single unit of production at the site of Itziparátzico is an estimated ten tons of copper and nearly forty tons of slag over the lifetime of the installation. It is argued that this smelting was based on slag-tapping furnaces, a technology previously unknown from Mesoamerican archaeological sites. The smelting site is in dense woodland with ample fuel supply, some 125 km from the next mining area with documented contemporary ore extraction; the copper produced would have been passed on to the capital, another 60 km away, for further distribution and working. The scale of production at Itziparátzico indicates that copper smelting was done by part-time specialists embedded in a predominantly agricultural economy, and formed part of a centrally organized network of mining, smelting and processing of copper to supply the Tarascan state.     

The Composition and Microstructural Variation of the Bronze Age Metal Ornaments from Lower Silesia (South‐West Poland): Chemical Analytical and Archaeological Aspects

Metal ornaments from Únětice (Mierczyce, Tomice, Jordanów and Opatowice) and Urnfield culture (Szprotawa, ?arek and Wroc?aw ?erniki) sites in south‐west Poland are made of bronze of varying composition, with the exception of the early Bronze Age Przec?awice site, where the copper items are found in graves from stages III/IV. The combined XRF and electron microprobe study of 37 ornaments (mostly pins) shows that those excavated from Únětice culture graves usually consist of cored dendrites, plus a Sb‐rich phase in some. The copper objects from Przec?awice correspond in composition to the East Alpine Copper or to the Ösenring copper and were produced from fahlore. Those from the Urnfield culture sites consist of homogeneous bronze. The Únětice culture ornaments were produced with little control of the effect of varying bronze composition on its microstructure. The results of XRF analyses of heterogeneous metal artefacts vary depending on the proportion of phases in the analysed site, and should be combined with micrometre‐scale analytical data and microstructural information yielded by electron microprobe methods. The same refers to deeply weathered or corroded objects made of homogeneous metal, which contain irregularly dispersed decomposition products.     

Mining Archaeology and Micro‐Raman Analysis Associated with ESEM‐EDX: Toward a Chrono‐Spatial Definition of Ore Consumption in a Pyrenean Medieval Workshop, 14th–16th Centuries

The rapid expansion of non‐ferrous metallurgy in the late Middle Ages (14th–15th centuries) enhanced ore demand, which was supported by mining intensification. Metallurgical workshops developed various supply strategies based on geological, political and economic constraints. This is particularly true for the Pyrenean multi‐metals workshop of Castel‐Minier (Ariège, France), where recent excavations unearthed an exceptional corpus of non‐ferrous ores. A specific analytical methodology combining micro‐Raman spectroscopy and environmental scanning electron microscopy with energy dispersive X‐ray (ESEM‐EDX) was set up to study these artefacts. This composite methodology permitted the fast characterization of both mineral and gangue as well as a discussion of their economic potential. Ores identified were compared with ancient mines in neighbouring mining districts in order to sketch a geography of the mineral resources available to medieval metallurgists. Moreover, a chrono‐stratigraphic study of ore distribution in Castel‐Minier revealed the supply strategies, technological choices as well as spatializing of copper and lead metallurgies.     

Percival,Vickers & Co. Ltd: The Archaeology of a 19th-Century Manchester Flint Glass Works

Abstract

The Percival, Vickers & Co. Ltd glass works was amongst the largest glass manufactories in Manchester, and formed one of a regionally significant group of 19th-century glass works in the Ancoats district of the city. All of these works have since been demolished, and the paucity of surviving physical and documentary evidence is in stark contrast to the former importance of the city's glass-making industry. The Percival, Vickers site was recently subjected to a detailed archaeological investigation ahead of redevelopment, providing a unique opportunity to study the buried remains of a 19th-century glass works. In particular, variation in the design of the furnaces provided evidence for the technological development of the later 19th century, which has not otherwise been documented. Additionally, some 110kg of glass fragments recovered from the site furnished important evidence for the composition of 19th-century glass, although the results are beyond the scope of the present paper, which focuses on the documented history, structural, and technological elements of the site.     

Variability in single smelting episodes – a pilot study using iron slag from Uganda

Most archaeometallurgical studies of iron smelting are based on the analyses of slag fragments randomly selected from slag deposits, and assume that these samples are representative of the typical smelting conditions of the given context. However, little archaeometallurgical research has been published to explore the variability in slag composition within a single smelt, or between individual smelts at the same production site. The material used in this pilot study originates from two iron smelting sites identified in the Buganda Kingdom, Uganda, dated to the 18th and 19th centuries AD. The remains represent evidence of the industrial scale iron production that supported the growth and power of the kingdom. The slag survives in large clusters of complete blocks, in some cases weighing over 100 kg, each resulting from a single smelting episode in a pit furnace. A multi-sample analytical approach has allowed an insight into the compositional diversity within the slag from single smelting events, reflecting changing parameters in the smelting systems. The internal variation of the slag blocks is subsequently compared within and between sites, to address issues of standardisation and to differentiate two technological traditions that would appear very similar at the macroscopic level. On this basis, some sampling recommendations are made for future slag block studies.     

A STUDY ON LATE MEDIEVAL TRANSPARENT‐GLAZED POTTERY AND ARCHAIC MAJOLICA FROM ORVIETO (CENTRAL ITALY)*

Nineteen samples of medieval transparent‐glazed pottery and archaic majolica from Orvieto (central Italy) were studied. They were classified by archaeological criterion as follows: five transparent‐glazed fragments with green and brown decorations (first half of the 13th century), eight green transparent‐glazed fragments (13th century) and six tin‐glazed fragments with green and brown decorations (second half of the 13th century). SEM–EDX, XRD (the Rietveld method) and XRF were used to characterize the chemical and mineralogical compositions both of the bodies and the coatings. In all of the samples, the paste is Ca‐rich with CaO contents as high as 13–20 wt%. The mineralogical composition is compatible with a firing temperature of about 950°C, which is the typical temperature reached in a wood kiln. No difference was observed between the bodies of transparent‐ and tin‐glazed pottery. In the case of transparent glazes, the burial conditions lead to heavy weathering of the samples. However, on the basis of the analyses carried out in non‐weathered areas, the typical composition is PbO 55–65 wt%, SiO₂31–35 wt%. In tin glazes, the tin is scattered on the mass of the glaze as SnO₂crystals with a concentration of 7–14 wt%. Concerning the decorations, it is established that the green colour is due to the presence of copper, while manganese is responsible for the brown colour. These pigments, which represent the typical colours of ‘archaic majolica’, are spread through the glaze homogeneously, apart from one case in which there is clear evidence of manganese oxide crystals.     

WROUGHT IRON FROM THE USS MONITOR: MINERALOGY,PETROLOGY AND METALLOGRAPHY*

The metal and its slag inclusions from the USS Monitor are mineralogical and geological artefacts of a vessel that has catalysed and documented the technology of maritime construction and warfare since 1862. Petrological study of a wrought iron disc from the hull of the Monitor reveals low‐carbon, high‐phosphorus ferrite with 4.8 vol% silicate slag, which includes phosphoran olivine, glass, wüstite and a silica polymorph. The sample, although made at the height of wrought iron manufacture, is of only mediocre quality and has a mineralogy, petrology and metallography that reflect the latter stages of puddling, rolling, annealing and 140 years of corrosion.