The early roman imperial AES coinage II: Tracing the copper sources by analysis of lead and copper isotopes—copper coins of Augustus and Tiberius*

Lead and copper isotopes of Roman Imperial copper coins (denominations as and quadrans) were analysed by MC–ICP–MS. We concentrated on well‐dated coins minted at the official mint of Rome under the Emperors Augustus and Tiberius (between 16 bc and ad 37). The lead isotope results were compared with published lead isotope data of ore bodies from the Aegaean, Cyprus, Italy and Spain, in order to fingerprint the sources of Roman copper. During the Augustan period the main copper supply, as judged from the copper coins, is from Sardinia and south‐east Spain, with minor contributions from Tuscany. Except for Tuscany, this continued into the Tiberian period, when Cypriot copper also appears. Augustan quadrantes and late Tiberian asses came solely from the Rio Tinto area in south‐west Spain. Copper isotopes were applied here for the first time to systematic archaeometric studies. They are supplementary to lead isotopes and allow further grouping and classification of the copper coins.     

Methods of Palaeodemography: The Case of the Iberian Oppida and Roman Cities in North‐East Spain

Ancient demography is a recurrent topic in archaeology, thanks to new methods and evidence from different surveys and excavations. However, different cultures or periods are studied on their own, without any comparison being made between them and of their population dynamics. The present paper seeks to advance the situation by defining methodologies to allow diachronic comparisons between two different periods and cultures. After setting out a methodological approach, the paper goes on to apply the same to a case study: namely the Roman conquest of north‐east Spain, comparing the demography of the ancient Iberian communities (fourth‐second centuries BCE) to the Roman colonization (first century BCE to first century CE). Roman urbanism is generally supposed to increase the population in a particular territory, but our present evidence refutes this point: a decrease in population is visible in urban or proto‐urban sites from the Iberian to Roman periods, though there is an increase in the rural densities.     

Characterisation of the raw metal sources used for the production of copper and copper-based objects with copper isotopes

Copper isotopes can be successfully used to determine the origin of copper or bronze artefacts from either primary or supergene sulphide or hydrocarbonate ores. In conjunction with lead isotopes, they provide information on the origin and type of the metal ore. We demonstrate this in this paper from the combination of literature and own data on metal ores and artefacts (coins and ingots). Low-temperature hydrocarbonates (esp. malachite and azurite) do not fractionate the copper isotopes amongst each other and have identical lead isotopes. Substantial fractionation of copper isotopes, however, occurs between copper sulphides and hydrocarbonates (malachite, azurite) such that the ⁶⁵Cu isotope is always enriched in the oxidised relative to the sulphide phase with a clear distinction between the two ore types. Expressed in the δ⁶⁵Cu notation, we assigned supergene sulphides to values less than −0.4‰ down to negative values of −2‰ and more, primary sulphides to a range between −0.4 and +0.3‰ and hydrocarbonates to positive values higher than +0.3‰. We have applied these boundaries to copper coins and ingots from the time of the Roman emperors with known ages from Augustus up to 250 AD. The deposit fields of the metal used for the production of the coins were previously identified from the lead isotope ratios to lie in the Southwest and the Central South of Spain. From the combination of the lead and copper isotopes and the exact time constrains, we could develop a picture of the change in mining activities in Spain involving continued mining sulphide ore deposits and, indicated by positive δ⁶⁵Cu values as proxies for malachite and azurite, the opening of new mines in various time slots. This first application shows that copper isotopes will become the most important tool in archaeometallurgy to distinguish between the exploitation of deeper-seated primary and supergene sulphide ores and shallower, secondary hydrocarbonate ores. This will become especially relevant for archaeometric questions regarding the distinction between occasional and intentionally produced alloys.     

Soil geochemistry and detection of early Roman precious metal and copper alloy working at the Roman town of Calleva Atrebatum (Silchester,Hampshire, UK)

A geochemical soil survey was carried out over 500 m² of a first and second century AD house complex in insula IX of the Roman town of Calleva Atrebatum (Silchester, Hampshire, UK) where there was little prima facie evidence for non-ferrous metalworking. Preliminary analyses were made by XRF of lead, zinc and copper. These were followed by analysis for Au, Ag and Sn by ICP-MS of the samples with the highest concentrations of Pb, Zn and Cu. Certain of the Pb, Zn and Cu concentrations suggest the working of copper alloy including brass, and could be associated with archaeological evidence of hearths and burnt areas of second century AD date. Other samples have concentrations of the above metals and of gold and silver which do not appear to be associated with any physical remains of hearths and burnt areas. These concentrations date to the mid-first century AD.     

ROMANO‐EGYPTIAN RED LEAD PIGMENT: A SUBSIDIARY COMMODITY OF SPANISH SILVER MINING AND REFINEMENT*

Samples of red pigment from a group of seven Roman‐period Egyptian mummies, known as red‐shroud mummies, are investigated. Elemental analysis by inductively coupled plasma time‐of‐flight mass spectrometry (ICP–TOFMS) shows that the samples contain mostly Pb (83–92% by weight), along with 0.2–2.0% Sn. All of the samples are found to have similar trace element distributions when normalized to the continental crust, suggesting that they share a common geological origin. Lead isotope ratios are found to match the mixed lead sources typically associated with Rio Tinto, Spain – a site extensively mined for silver during the first century ad . Raman microspectroscopy identifies the major phase of each sample to be red lead (Pb₃O₄) with a minor phase of lead tin oxide (Pb₂SnO₄). Lead tin oxide does not occur naturally, and its incidental occurrence within the sample indicates that the material was heated under oxidative conditions at temperatures in excess of 650°C. In archaeological contexts, the high‐temperature oxidative treatment of lead is typically associated with metallurgical refinement processes such as cupellation. Based on this evidence, it is argued that the pigment was produced out of litharge associated with silver cupellation at the Rio Tinto site.     

First comprehensive peat depositional records for tin,lead and copper associated with the antiquity of Europe's largest cassiterite deposits

Tin, as a constituent of bronze, was central to the technological development of early societies, but cassiterite (SnO₂) deposits were scarce and located distantly from the centres of Mediterranean civilizations. As Britain had the largest workable ore deposits in the ancient Western world, this has led to much historical speculation and myth regarding the long-distance trading of tin from the Bronze Age onwards. Here we establish the first detailed chronology for tin, along with lead and copper deposition, into undisturbed ombrotrophic (rain-fed) peat bogs located at Bodmin Moor and Dartmoor in the centre of the British tin ore fields. Sustained elevated tin deposition is demonstrated clearly, with peaks occurring at 100–400 and 700–1000 calendar years AD – contemporaneous with the Roman and Anglo-Saxon periods respectively. While pre-Roman Iron Age tin exploitation undoubtedly took place, it was on a scale that did not result in convincingly enhanced deposition of the metal. The deposition of lead in the peat record provides evidence of a pre-Roman metal-based economy in southwest Britain. Emerging in the 4th century BC, this was centred on copper and lead ore processing that expanded exponentially and then collapsed upon Roman colonization during the 1st century AD.     

X-ray fluorescence analysis of late Roman and Sassanian silver plate

About 200 analyses have been made on late Roman and Sassanian silver objects using energy-dispersive X-ray fluorescence. This has shown that the main feature of the composition of the silver throughout the period and across the geographical area studied was towards high fineness (average silver percentage about 95%). Compositional differences are found between Roman and Sassanian silversmiths' products for the elements copper and lead. Much of the material analysed came from hoards, and using a statistical technique on the analytical data (Discriminant Analysis) broad compositional differences between hoards were found to emerge. The use of different compositions of silver for different joined parts of a single object are discussed.     

Non-ferrous metallurgy from the Phoenician site of La Fonteta (Alicante, Spain): a study of provenance

The lead isotope composition of 22 samples from the excavation of the Phoenician site of La Fonteta (Guardamar del Segura, Alicante, Spain) has been analysed in a preliminary study of their provenance. These materials span chronologically from the first half of the 8th century BC to the middle of the 6th century BC.The samples have been selected to include materials used in lead and silver production, as well as in copper-based metallurgy. Therefore, lead droplets, galena nodules and fragments of litharge have been analysed, together with a fragment of a copper ingot, an object, a melting waste composed of a Cu–Pb alloy, and two fragments of a material that we have provisionally labelled ‘Pb–Cu cupellation debris’.All these materials have been initially analysed by X-Ray Fluorescence-Spectrometry to identify their bulk compositions. Some of them have been also analysed by SEM–EDX and ICP–OES. Subsequently, lead isotope analyses (LIA) have been performed using Thermal Ionization Mass Spectrometry (TIMS). The new LIA data obtained has been compared with published lead isotope data from the Mediterranean area. The identification of different groups suggests a significant complexity of the internal and external trade routes during the Orientalising period. For this reason, the provenance study of these materials is especially important in shedding light on the commercial dynamics that the Phoenicians established with native people to control the raw materials and to commercialise finished products.     

THE ATLANTIC ROMAN TRADE DURING THE PRINCIPATE: NEW EVIDENCE FROM THE WESTERN FAÇADE

In this paper new evidence is presented for long‐distance trade in the western Atlantic in the Roman period, chiefly from Augustus to the second century AD, on the basis of documented shipwrecks and numerous amphora types. Well‐dated contexts from northern Portugal and Spain, as well as similar sites in northern France and Germany, suggest a thriving trade of amphora‐borne commodities during the Principate. The Atlantic route was initially developed during Augustus' campaigns against the Cantabri and Astures, and later consolidated with the exploitation of the mines in the north‐west of the Iberian Peninsula. Supplying the Roman armies in the German Limes gave a new impetus to this commercial route, complemented by the conquest of Britain.     

A THOUSAND AND ONE COLUMNS: OBSERVATIONS ON THE ROMAN GRANITE TRADE IN THE MEDITERRANEAN AREA

Summary.   Provenancing and archaeological information on Roman granite columns in the Mediterranean area has been collated from a range of published papers by the author and others, together with new analyses for Rome, to produce an integrated dataset comprising 1176 columns. This dataset allows an overview of Roman granite trade in seven regions across the Mediterranean area. Examination of the data indicates that columns made from Troad (Turkish) granite are the most numerous observed overall (compatible with Lazzarini's earlier (2004) observation that this is the most widely distributed type), followed by Aswan, then Elba and Giglio, and Kozak Dağ ( Marmor Misium ). In the city of Rome, Mons Claudianus columns predominate. In geographically peripheral parts of the Roman world (Spain, Israel), granite columns are mainly from local sources, and are generally of smaller sizes than those seen in Rome and Tuscany. Analytical data can be used to suggest multiple extraction sites within some quarries, and have the potential for identification of specific intra-quarry provenance. Dating evidence for primary use of columns from the quarries considered is relatively sparse, but suggests early (first century BC) exploitation of Spanish and Elba granites, while column production at Aswan and Troad persisted into the fourth century followed by reuse within later antiquity, in the fifth and seventh centuries AD.     

THE COMPOSITION OF IRON AGE STRUCK 'BRONZE'COINAGE IN EASTERN ENGLAND

EDXRF was used to analyse the composition of 88 Iron Age copper and copper alloy coins excavated from the site of a pre-Roman shrine and Roman temple at Harlow, Essex. Most of the coins are local to the Essex-Hertfordshire region, with a few of Kentish origin. The earliest struck base metal issues were struck from almost pure copper, but from the late first century BC, their composition shows more variety. Particularly interesting are a group of types belonging to the Romanizing phase of Tasciovanus'coinage, which were struck in brass and possibly represent a distinct denomination. Roman coinage and other metalwork imports from the Roman world presumably provided the initial impetus, and the ultimate source of the brass. However, this experiment was relatively short lived. Cunobelinus, who ruled eastern England during the earlier first century AD, mainly employed bronze to strike his abundant base metal coinage. The products of his Colchester mint reveal a consistently different composition from those struck at his unlocated second mint in the Hertfordshire area, although the precise alloy does vary, sometimes within the same type. This suggests that unlike gold and silver issues, the source and purity of the metal used for minting base metal coinage was not always critical.     

Text and image in celtiberia: the adoption and adaptation of written language into indigenous visual vocabulary

Summary This study is concerned with the relationships between text and image in central Spain during the period second century BC–second century AD. Three discrete relationships are isolated, each one representative of a unique strategy for communicating with both written and figured language. The paper argues that the Celtiberian populi adopted Roman epigraphic practice into a pre-existing visual vocabulary, reconfiguring written communication into an indigenous framework that met local predilections.     

CYPRIOT BYZANTINE GLAZED POTTERY: A STUDY OF THE PAPHOS WORKSHOPS

Twenty‐five samples of Byzantine glazed pottery from two archaeological sites between Limassol and Paphos region (Cyprus), dated between the 12th and 15th century ad were studied using micro X‐ray fluorescence spectroscopy, scanning electron microscopy and X‐ray diffraction analysis. It was found that all the glazes contain lead, following the main manufacturing process of medieval pottery in the Mediterranean territory, while some of them contain tin, possibly for better opacity. Furthermore, it is shown that copper, iron and cobalt with nickel are responsible for the decoration colours. Finally, the application of principal component analysis revealed significant differentiation for some of the samples.     

The Baelo Claudia Paradigm: The Exploitation of Marine Resources in Roman Cetariae

The Roman city of Baelo Claudia (Baetica, Hispania) is one of the best known halieutic sites of the Mare Nostrum, dating from between the 2nd century BC and the 5th century AD. Recent archaeological investigations have included the discovery, excavation and interdisciplinary study of two new fish-salting factories (so-called “Conjuntos Industriales” XI and XII), providing valuable new information on the exploitation of marine resources. This paper provides the first synthesis of all of the available archaeological evidence for the first three phases of the fishing-product cycle (marine resources/fishing equipment/processing facilities and food products) at this unique site on the Strait of Gibraltar.     

On Early Thimbles: A Seventh‐Century‐AD Example from Punta Secca,Sicily, in Context

A copper‐alloy thimble was found in 2010 at Punta Secca, Sicily, in a sealed context datable by coins to the first quarter of the seventh century AD. It has generally been thought that thimbles did not reach the Mediterranean area until the ninth century AD, but at least nine metal examples are in fact attested at various places from contexts datable between the late sixth century and the early ninth. It is suggested that the increasing use of silk in clothing in the Byzantine Empire during the seventh century, probably accompanied by the use for the first time of steel needles which made the use of a finger protector imperative, explains the apparent introduction of thimbles at this time. No securely dated metal thimbles are known from sites of Roman date, except for one at Ephesus of c.AD 100. It is very tentatively suggested that this last example might represent an import from China, where thimbles (and steel needles) are attested from at least the third century BC onwards.     

LEAD ISOTOPIC ANALYSIS OF COPPER ORES FROM THE SIERRA EL ARAMO (ASTURIAS,SPAIN)*

This study presents the first ever lead isotope ratio data for copper ore samples (malachite and azurite) from the Sierra El Aramo (Asturias, northwestern Spain). The aim of this study was to supplement information in the existing reference database on the lead isotopic composition of Spanish ores. The Sierra El Aramo is particularly important because, while no data for the Asturian ores have been published so far, this northern province of Spain has played a significant role in terms of copper exploitation and metallurgy since the Copper Age.     

Local mining or lead importation in the Roman province of Africa Proconsularis? Lead isotope analysis of curse tablets from Roman Carthage,Tunisia

This study attempts to determine if there was Roman lead mining in Africa Proconsularis, approximately the area of modern day Tunisia, using lead isotope analysis. Another important aspect of the study is the innovative use of electron microprobe analysis (EMPA) as a screening tool to greatly reduce the number of expensive lead isotope analyses needed for the study. The EMPA X-ray mapping for arsenic, antimony, copper, and silver narrowed the sample of curse tablets to those most likely produced from Tunisian ores; these tablets were then tested using thermal ionization mass spectrometry (TIMS) analysis. A total of 96 Roman lead curse tablets from Carthage, Tunisia were screened with EMPA and twenty selected for TIMS to determine the ore sources of the lead used to manufacture the tablets. Comparing the lead isotope ratios of twelve of the sixteen tablets most likely to be made of Tunisian lead to samples of Tunisian ores suggests that the Romans were mining lead in Africa Proconsularis and were not relying solely on imports.     

ROMAN WINDOW GLASS: A COMPARISON OF FINDINGS FROM THREE DIFFERENT ITALIAN SITES

Thirty‐three samples of window glass and five glass lumps coming from three Italian archaeological sites—the Suasa excavations (Ancona, settled from the third century bc to the fifth to sixth centuries ad ), the Roman town of Mevaniola (Forlì‐Cesena, settled from the Imperial Age up to the fourth century ad ) and Theodoric's Villa of Galeata (Forlì‐Cesena, settled from the sixth century ad onwards)—were analysed to track the changes in the chemical composition and manufacturing technology of window glass through the centuries. The aims of this study were: (1) to establish the origin of the raw materials; (2) to verify the chemical homogeneity among samples coming from different sites and/or produced using different techniques; and (3) to sort the samples into the compositional groups of ancient glass. The analysis of all the chemical variables allowed two groups to be distinguished: (a) finds from Mevaniola and Suasa; and (b) finds from Galeata. All the samples had a silica–soda–lime composition, but the analysis of minor elements—in particular, of Fe, Mn, and Ti—made it possible to split the samples into two groups, with the higher levels of these elements always found in the Galeata samples (HIMT glass). In conclusion, it can be asserted that the main differences between the samples are related to their chronology.     

中国钱币博物馆部分陈列银币、铜币的腐蚀产物及成因研究

为探讨部分陈列银币、铜币腐蚀产物及其成因,采用三维视频显微镜、扫描电镜-能谱(SEM-EDS)、X射线荧光(XRF)、X射线衍射(XRD)等方法,对中国钱币博物馆部分遭受腐蚀的展陈钱币的腐蚀产物进行了分析,并通过红外光谱(FT-IR)对展陈材料进行了分析,最后对硫的来源进行了初步分析。结果表明,银币和铜币的腐蚀产物均含有硫化物,银币(银铤)的腐蚀产物为硫化银,铜币的腐蚀产物中主要为铜的硫化物,此外还含有铜的氧化物。经分析,展柜中的黏合剂氯丁胶在光照和较高温湿度条件下能分解并释放出硫化氢气体,因而初步判断银币或铜币的腐蚀产物是由于展柜内材料产生的硫化氢与银币或铜币反应生成。     

天然氧化铜矿与铜制品腐蚀产物区别的探讨

在一些新石器时代的遗址中经常会出现一些铜渣、小块孔雀石等与炼铜有关的遗物。为探究这些孔雀石到底是天然的氧化铜矿还是铜制品的腐蚀产物,本工作对天然氧化铜矿和青铜器腐蚀产物进行岩相分析和元素成分分析。结果表明,天然氧化铜矿大都具有一些特殊的结构构造,而在铜制品的腐蚀产物中却很难发现这些结构构造;同时,二者在元素成分上也有显著不同,Bi、Sb、As、Fe、Mo、Co、Mn等微量元素可以作为区分天然氧化铜矿和青铜器腐蚀产物的一个判别标志。结合岩相分析和成分分析,可以确定一个遗址出土的孔雀石或蓝铜矿是天然氧化铜矿还是铜制品的腐蚀产物;同时,可进一步判断是红铜的腐蚀产物还是青铜的。这一结论对探讨铜冶金的起源有重要意义。