QUANTITATIVE ANALYSIS OF COPPER-TIN BRONZES BY MEANS OF GLOW DISCHARGE OPTICAL EMISSION SPECTROMETRY

Glow discharge optical emission spectrometry (GDOES) has been used for obtaining calibration curves for copper, tin, lead, silver, antimony, arsenic, zinc and iron from standards including copper-base alloys (Cu 61.33-99.95%) and from bronze Punic coins. The GDOES results were calibrated using atomic absorption spectroscopy with inductively coupled plasma atomization (ICPAAS) to analyse the standards and coins. For all these materials, the results show that via GDOES it is possible to obtain reliable and reproducible calibration curves for copper, tin, lead, zinc and iron with a linear behaviour as a function of the content. The quantitative GDOES and ICPAAS data for the coins have been also compared with those obtained via X-ray fluorescence (XRF) and it is shown that GDOES, ICPAAS and XRF agree well with one another considering that the bronze coins are inhomogeneous to some degree. As an example of GDOES analytical features, a depth concentration profile through a thin bronze patina is shown and briefly discussed.     

MICROSTRUCTURAL CHARACTERIZATION OF EARLY WESTERN GREEK INCUSE COINS*

In this research, we studied the compositional, crystallographic and microstructural properties of a series of incuse silver didrachmae stemming from the Achaean colonies of Metapontum and Caulonia. In this paper, we address the following points: (i) the metal sources, (ii) the fabrication process and (iii) degradation phenomena, such as incrustation and embrittlement. In this investigation, we employed energy‐dispersive X‐ray fluorescence spectroscopy, X‐ray diffractometry, and scanning electron and optical microscopies. The patina is mainly composed of chlorargirite. The coins consist of a silver‐rich alloy containing ～ 1% of Au and Cu. Metallographic and local compositional analyses revealed a complex scenario of inclusions. In one instance, unalloyed copper grains, two‐phase copper/bismuth globuli and high‐bismuth filaments were observed. In other cases, globular Cu ₂ S (chalcocite) inclusions were noticed. The presence of SiO ₂ and iron oxide inclusions is ubiquitous in these samples. Distorted twin lines and strain lines can be detected, denoting work‐hardening of recrystallized flans. Grain polygonalization can occasionally be noticed, hinting at secondary recrystallization processes. The irregularly shaped iron oxide particles often act as crack initiation sites. Fracture facets are generally intergranular. On some areas, intergranular decohesion is also observed. Open cracks sometimes contain AgCl. The strain lines that can be noticed on the fracture surfaces indicate work‐hardening and residual microstructural deformation. Information regarding inclusions and the presence of significant amounts of gold can be tentatively used to address provenancing and fabrication issues.     

PRE-COLUMBIAN METALLURGY: TECHNOLOGY,MANUFACTURE, AND MICROPROBE ANALYSES OF COPPER BELLS FROM THE GREATER SOUTHWEST*

Twenty-four cast copper crotals (commonly called bells), one 'spilled bell’, one tinkler bell and a number of minerals from locations throughout the Greater Southwest were analysed for their elemental composition by a PIXE nuclear microprobe at Los Alamos National Laboratory, New Mexico, USA. Sixteen bells contained minor and trace amounts of silver, antimony, arsenic, lead, and in some cases tin, strontium, and selenium. Nine bells contained little or no detectable amounts of these elements. This suggests that several workshops throughout the Greater Southwest and Mexico might have manufactured these bells.     

The cologne map publisher Peter Overadt (fl. 1590–1652)

Abstract

Peter Overadt is one of the many lesser‐known figures of the second generation of the Cologne school of map making, which had been founded about 1570 by Frans Hogenberg. Overadt is noteworthy as the first continental publisher (aside from Jodocus I Hondius, who was at that time active in London) to have decorated printed topographical maps with marginal historical‐political images. During the first phase of his business (1592–1600), he issued eight maps, with a three‐sheet map of Germania as the pinnacle of his production. After 1600, Overadt's firm was primarily engaged in the publication of religious prints with a Catholic orientation. Topographical productions from this later period are three large town views and the re‐issue of a map of the Rhine area, printed from a re‐worked copper plate of 1594 by Theodoor de Bry.     

Precision in the X-ray fluorescence analysis of sixty-one Augustan quadrantes

Sixty-one Augustan quadrantes were analysed for calcium, iron, nickel, copper, silver, tin, antimony, and lead by X-ray fluorescence. Most coins contained about 99·7% copper with the other seven elements present as trace impurities. Significant differences in composition were found for the three different issues of quadrantes minted in c. 9 BC indicating that these issues were not minted exactly contemporaneously. Quadrantes minted in c. 4 BC have trace element concentrations in ranges that differ from those of the 9 BC quadrantes. The precision is very good for all trace elements (the precision of calcium was not calculated): average standard deviations are 0·0021% for Fe, 0·0026% for Ni, 0·0038% for Ag, 0·0014% for Sn, 0·0031% for Sb, and 0·015 for Pb.     

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.     

EARLY BRONZE AGE TIN PROCESSING AT KESTEL/GÖLTEPE,ANATOLIA

Chemical analysis of statistically significant numbers of samples including minerals, sediments, soil, host rock as well as powdered materials, crucible accretions and metal artefacts revealed information about the distribution of cassiterite at Kestel and the tin smelting processes that took place at Göltepe c. 2600 BC. Using the ancient technique of vanning for the isolation of tin ore (cassiterite), followed by assaying by blowpipe/charcoal block, as well as crucible smelting with a blowpipe, good tin metal suitable for alloying with copper to make bronze was obtained. There is every indication that tin was mined and smelted in the Early Bronze Age at the Kestel/Göltepe sites.     

Late horizon silver,copper, and tin from Machu Picchu,Peru

Analyses of silver–copper alloy artifacts from Machu Picchu show silver contents ranging from 24 to 81%. The tin present, ranging up to 3%, originated with the copper, perhaps from admixture of recycled bronze. The presence of 0.4–0.9% lead in the silver-rich phase indicates use of silver prepared by cupellation. All the objects had been forged after casting, some extensively. All have surface enhancement of the silver arising from depletion of the copper-rich phase. Some of the tin found at the site contains inclusions of hardhead (FeSn₂) and of a nickel–arsenic–copper compound. Forming trials with duplicate silver–copper alloys show that intermediate anneals at temperatures between 500 and 600 °C facilitate making thin sheet artifacts. Mechanical tests show that the most commonly used alloys, containing 25–30% silver, are particularly well adapted to forging because of their uniform work hardening during plastic deformation. Annealing of the laboratory-made alloys in air followed by boiling in salty weak acid creates a silver-rich surface layer comparable to that found in the artifacts. Depletion forms a dense silver surface on the alloy containing more silver than the eutectic composition, but a porous surface layer on the 25% silver alloys.     

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.     

成都市博物院几件院藏青铜兵器的分析研究

为了解巴蜀青铜兵器的制作技术及表面斑纹形成机理,采用金相显微镜分析,扫描电镜及能谱仪对成都市博物院的几件带斑纹的馆藏青铜兵器进行了分析。结果表明,两件截面样品均为青铜铸造组织,锡含量平均为11％。三件器物表面斑纹层均含锡和铜并具有一定抗氧化作用。斑纹工艺可分为二类：剑周99-1极可能为直接铸出凸凹不平的剑体,在凸起部位涂高锡合金膏剂,加热处理后得到。另一类可能先直接铸出金属基体,在欲成斑处涂抹合金膏剂或纯锡,加热处理打磨得到。分析结果可为深入研究巴蜀青铜兵器提供参考。     

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.     

Cornish tin-streamers and the Australian gold rush: technology transfer in alluvial mining

Abstract

The Cornish are known around the world for their mining skills. In the 19th century the migration of Cornish mining families created a diasporic community with settlements in the United States, Mexico, South Africa and Australia centred on copper, tin and gold mines. While the Cornish are generally associated with underground mining, recent research in Australia suggests that ancient methods for working surface tin deposits played an important role during the gold rush. The identification of Cornish tin-streaming as the source of alluvial mining technology in Australia sheds light on a little-documented branch of mining that has played a significant role in shaping the landscape of goldfields regions.     

The Flax Spinning Mill in Mysłakowice near Jelenia Góra,Poland

Abstract

The Orze? flax spinning industry in Mys?akowice has a manufacturing tradition extending back to 1839 when the Flachsgarn Maschinen Spinnerei und Weberei was set up in Erndmansdorf in Lower Silesia. The development of the works is documented by well-preserved factory buildings in which the same manufacturing process has been taking place for 150 years. The cast iron frame of the spinning mill may also be regarded as a pioneering structure in Silesian industrial buildings.     

THE BLACK INLAY DECORATION ON A MYCENAEAN BRONZE DAGGER*

The black inlay decoration with superb marine, hunting and other scenes on Mycenaean bronze daggers and silver cups has often been referred to in the literature as niello—a mixture of sulphides of copper, silver or lead—despite the absence of any systematic analysis of these precious metal artefacts. This paper presents semi-quantitative surface analyses of an example of black inlay on a Mycenaean dagger, now in the Archaeological Museum at Patras in Greece. Using non-destructive X-ray fluorescence spectrometry, it has been established that, contrary to the traditionally-held view, the black inlay is a copper-gold alloy with some silver and possibly small amounts of tin.     

METALLURGY OF BRONZE USED IN TOOLS FROM MACHU PICCHU,PERU*

Although the tin‐bronze artisans’ tools found at Machu Picchu appear to have been cast to their final shape, examination of their microstructures shows that they were forged and annealed. As found, the tools were broken or cracked due to poor ductility of the bronze. Rolling and annealing of samples of bronze formulated with sulphur and iron additions to replicate the metal used at Machu Picchu show that the minimum amount of deformation needed to induce the observed recrystallization is a 12% reduction in thickness. The sulphur and iron impurities retard nucleation of new grains during annealing, but do not inhibit subsequent grain growth. Tensile tests show that while up to 10% porosity in cast bronze has no effect on hardness or initial strain‐hardening rate, it reduces the tensile strength and ductility enough to embrittle the metal. Hardness is an inadequate indicator of the strength properties of cast bronze intended for use in tools or weapons. The results show that when the metalsmiths at Machu Picchu started making bronze tools for use by stone and woodworkers, they had not mastered the art of making metal with adequate strength properties for this service. The forging and annealing procedure they used did not enhance the mechanical properties of their tools, and may reflect an inherited metallurgical tradition.     

The Role of Functional Efficiency in the Decline of North America’s Copper Culture (8000–3000 BP): an Experimental,Ecological, and Evolutionary Approach

The copper-using cultures of North America’s Archaic Period (10,000–3000 BP) have long been an archaeological enigma. For millennia, Middle and Late Archaic hunter-gatherers (8000–3000 BP) around the Upper Great Lakes region made utilitarian implements out of copper, only for these items to decline in prominence and frequency as populations grew and social complexity increased during the Archaic to Woodland Transition. From a cultural evolutionary perspective, the trajectory of North America’s copper usage presents a conundrum, as it is generally assumed that “superior” tools, i.e., metals, will replace inferior ones, i.e., stone. For well over a century, scholars have pondered the reason for the demise of copper technology that was once a wide-spread phenomenon. To address this question, an extensive archaeological experimental program was conducted which compared replica copper tools (spear points, knife blades, and awls) to analogous ones made of stone or bone to assess whether relative functional efficiency contributed to the decline of utilitarian copper implements. Here, the results of this three-part research program are presented in concert with population dynamics and ecological change to paint a broader picture of the complex interrelationships between the social, ecological, and technological spheres of past human behaviors. The synthesis of these approaches reveals that functional explanations—derived from experimental archaeology placed in an evolutionary framework—can shed much light on the trajectory of metal use in the North American Great Lakes.

     

Notes on the Design and Construction of Urban's Giant Bombard

Abstract

The advent of the large gun known as the bombard meant that the medieval city could no longer ride out a siege behind the security of its formerly impregnable walls. Fifteenth-century Europe saw the development of two broad families of particularly large ordnance: the wrought iron bombard of western Europe and the cast bronze bombard of eastern Europe.     

A Constructive Approach to Sculpture

Abstract

In the production of a sculpture, practical and technical considerations have a large influence. Some of these are here reviewed as seen through the author's eyes and as based on his personal experience. Such materials as concrete, cast iron and stainless steel are discussed, classical and contemporary fashions are compared, the importance of linking straight lines and curves in sculpture is emphasised, and the design process is outlined. The review concludes with a discussion of the heart of all artistic work, inspiration.     

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.