Lead Metallurgy

This study provides the first evidence for the extraction of lead in the later early medieval period in Lancashire, in the North West of England. Archaeological evidence for human activity in the region during the later medieval period is modest, although the material culture that is known supports the historic accounts of settlement by people of Scandinavian origin, which is reinforced by studies of place names and local dialect. Investigation of two upland sites in the western Pennines, on Anglezarke and Rivington moors, indicates that lead was being extracted in the period c.680-1000 cal.AD, most likely from known veins at Lead Mines Clough. The emergence of extractive activity coincides with contact with the Norse who are known from both historic and archaeological evidence to have been present in Lancashire during the later early medieval period.

KEYWORDS
EARLY MEDIEVAL, LEAD, MINING, MINERAL EXTRACTION, MAGNETIC MEASUREMENT, SATURATION ISOTHERMAL REMANENT MAGNETISATION ASSAY, HEAVY METAL (LEAD) ASSAY, METALLURGY, UPLAND, PEAT, LANCASHIRE, ARCHAEOLOGY, ARCHAEOLOGICAL METHOD, NORSE ARCHAEOLOGY

This paper is about the trade of copper originating from the Harz Mountains or, more specifically, from Goslar, and concentrates on the period between the 12 th and 14 th centuries. The Harz Mountains
can be regarded as the largest and most important copper source of medieval Central Europe until the rise of copper production in Falun in the 14 th century, and mining historians have shown that the trade of metallic products from the Harz was well established by the 12 th century. The recent study of Huneberg has provided a model for the production capacity of a typical 12 th century woodland smelting site producing copper and lead in one of medieval Europe's foremost mining areas.
Historians have documented the extent of metal production and trade in Goslar, an important source for raw materials that could be transported up the Rhine to market towns like Cologne and to the Meuse valley, important centres for the production of copper alloy goods. Combining our understanding of the histories of trade and mining allows an approximation to be made of the production volume of the Harz per year for the medieval period. These estimations tally quite well with
the demand for copper known to us from written sources, such as the copper roof of the cathedral of Goslar from 1050 or the copper order for the Bamberg cathedral's roof by Bishop Otto in 1128.

This study provides the earliest unambiguous evidence for the extraction of lead in Northern Europe. Previous studies of early metal extraction have focused on copper ores in Ireland, with an increasing number of mines identified in western Britain, particularly in mid‐ and north‐Wales, in recent years. The evidence presented here focuses on the extraction of lead in the north‐west of England, extending our understanding of metal extraction beyond copper ores. Radiocarbon dating of sample sites to c.1800 cal.BC places anthropogenic activity in the British Early Bronze Age, challenging assumptions that lead was first utilised in the Middle Bronze Age period in Britain. Excavation of two Early Bronze Age burials, of contemporaneous date, found Collared Urn cremations with associated crystals of galena, placed as apparent grave offerings, inviting the possibility that they are the graves of putative mine workers.
KEYWORDS
EARLY BRONZE AGE, LEAD, MINING, MINERAL EXTRACTION, MAGNETIC MEASUREMENT, SATURATION ISOTHERMAL
REMANENT MAGNETISATION ASSAY, HEAVY METAL (LEAD) ASSAY, PREHISTORIC METALLURGY, COLLARED URN BURIAL,
UPLAND, PEAT, LANCASHIRE, ARCHAEOLOGY, ARCHAEOLOGICAL METHOD, EUROPEAN BRONZE AGE, BRITISH BRONZE AGE

Excavations in 2002 at Cwmystwyth, in Central Wales, found an ancient lead smelting site. There are remains of the medieval and the Roman periods. This paper describes in brief the excavation of the medieval lead bole but also provides an archaeological reconstruction of this and details of an experimental lead smelt carried out at the site in 2003 (by ST). The analytical study (by LA) is of the medieval metallurgical debris excavated in 2002, mostly slag, but also ore and lead. The aim was to understand the raw material, the metal produced and the smelting process. The ore smelted was predominantly galena but with no detectable silver, showing it was probably exploited to produce lead. The extremely high sulphur content of the slag indicates that the ore was not roasted before smelting. It is argued that the medieval activity was small-scale, smelting a very rich ore. The furnaces apparently did not require much capital investment, enabling a short-lived and/or exploratory smelting operation.

Two sets of archaeological lead objects from different sites were analysed by ICP-OES for several minor and trace elements in a) the metal and b) the patina. For the first time, detailed analyses of well provenanced and coherent groups of, respectively, LBA Egyptian and 1st century AD Germanic lead objects are given, and interpreted for their metallurgical significance. Besides this, characteristic systematic differences in the composition of metal and patina were found for the two sets for various trace elements, including silver, copper, tin, antimony and arsenic, paralleled by a different mineralogy of the respective patinas.

The analyses in two large lead vessels indicate that the lead metal most likely comes from the Laurion ore deposit. The lead isotope ratios for all samples are within the error margin identical, and in good agreement with an origin of the metal from Laurion. The lead isotope evidence for a common origin of the lead from one ore deposit, and the slight chemical difference between the two vessels, are not in contradiction to each other. Rather, it is an indication that the lead metal comes from the Laurion area but from different smelting sites, possibly including Agrileza. Laurion lead ore is known to have had about 1000 ppm silver and to be chemically different between different parts of the ore deposit. The relatively low silver levels in Vessel B, and medium in Vessel A, could indicate that they underwent different metallurgical treatment. The metal from Vessel B is possibly desilvered, while Vessel A may have been made from metal deemed to poor in silver to merit desilvering. However, further work would be necessary to more closely identify the origin and metallurgical history of the lead metal from Iolkos. The manufacturing evidence for these vessels is also of interest. The X-ray image of Vessel A showed that it consists of two lead sheets hammered and joined together in the mid-height of the vessel. Also, a double line is obvious at the maximum circumference in the internal surface of the vessel. This is probably due to preferential corrosion at the metal joint, and further confirms the X-ray image.
The vessels perfectly fit S. Mossman’s description of such vessels, such as the vessels found in the area of ancient Mycenae as well as in Midea.
The corrosion products as shown from XRD analyses are mainly lead carbonate salts, cerussite and hydrocerussite, as well as lead oxide which has corroded the majority of the surface in both vessels. Despite its better morphological preservation, Vessel A is internally badly corroded and does not preserve much metal core. Vessel B, in contrast, is internally in better condition and preserves a good metal core.
There are no traces of repair and there is no decoration visible on these vessels. They were possibly used for the collection or storage of water, and may have been set into a block of clay or soil to give them the necessary mechanical stability when full.

Presentem l’estudi d’una mostra representativa d’objectes de plom, recuperats durant els treballs d’excavació a l’establiment de Sant Miquel de Vinebre (la Ribera d’Ebre) amb l’objectiu d’obtenir el màxim d’informació referent al seu procés de fabricació (assaig de reconstrucció de la cadena operativa), possibles aplicacions, funcionalitat i reciclatge, així com l’origen, procedència, vies de circulació, transport i distribució del mineral. Per tal d’aconseguir el nostre propòsit, mostrem els diferents tipus d’instruments en un quadre sinòptic, on fem constar els trets diferencials dels més representatius amb marca. (Vegeu taula I) Així mateix, recopilem totes les marques deixades sobre aquest tipus de suport a fi d’extreure’n algunes conclusions de conjunt sobre llur significat.

Résumé/Abstract Excavations in 2002 at Cwmystwyth, in Central Wales, found an ancient lead smelting site. There are remains of the medieval and the Roman periods. This paper describes in brief the excavation of the medieval lead bole (Timberlake 2002a) but also provides an archaeological reconstruction of this and details of an experimental lead smelt carried out at the site in 2003 (by ST). The analytical study (by LA) is of the medieval metallurgical debris excavated in 2002, mostly slag, but also ore and lead. The aim was to ...

A wide-ranging study based on compositional and isotopic analyses of minerals and manufactured objects from the north-eastern Iberian Peninsula and their respective archaeological and cultural contexts demonstrates significant lead mineral exploitation in the El Priorat area (Tarragona province) linked to Phoenician trade (seventh–sixth centuries BC). This exploitation continued, despite losing intensity, until the Romanization of the territory. Our project also aims to determine the nature and origin of the lead and silver supply in the northern Iberian territory surrounding the Phocaean enclave of Emporion, especially with regard to the demands of the colonial mint. The behaviour pattern of the circulation of lead, silver and copper in Catalonia in the period studied indicates a plurality of contemporary supply sources, although, at least from the fifth century BC onward, minerals and metals from the south-eastern Iberian Peninsula take on considerable importance.

Although only eight samples were analyzed from both sites, the present data demonstrate that some important information can be gained from the analysis of even these few lead objects. The first results indicate that fresh desilvered, and not recycled, lead was used in most cases. Small quantities of copper, antimony and arsenic, typical for ancient lead, are present throughout, and traces of some other elements at or just below the detection limits. There are some subtle differences in antimony and arsenic levels between the samples from Demetrias and Pherai. Tin in particular is an indicator for possible recycling of lead, as it does not normally occur geologically with lead deposits, but is frequently incorporated in scrap lead as pewter or solder. Wyttenbach and Schubiger (1973) found up to 10 ppm tin in Roman lead ingots, but several hundred to thousands of ppm in lead pipes. The values found here are thus in line with the use of fresh metal, as was already found to be the case for the copper in an earlier study (Asderaki & Rehren 2002). The lead sheet 876, though, which is also isotopically different, has nearly 200 ppm tin, and could well include a component of recycled lead metal.
The lead isotope signature of the metal, in all cases but two, is compatible with their origin from a single source, Laurion. Those samples with a higher 207Pb / 206Pb ratio may either indicate that the Laurion field is indeed more complex than previously thought, or that these samples come from a different source, such as the Chalkidiki (Stos pers.com 2004). This further underlines that the mining district of Laurion continued to be the dominant provider of metal even during the Hellenistic period, when we have little historical evidence for ongoing mining there. The potentially more complex lead isotope signature of the Laurion region, and the overall pattern of lead provision and trade in Hellenistic central Greece, requires further work in order to confirm the above results and conclusions. The full evidence from a wider range of materials and archaeological features has to be considered, and we hope to make a contribution to the ongoing research in this area.

Excavations in 2002 at Cwmystwyth, in Central Wales, found an ancient lead smelting site. There are remains of the medieval and the Roman periods. This paper describes in brief the excavation of the medieval lead bole (Timberlake 2002a) but also provides an archaeological reconstruction of this and details of an experimental lead smelt carried out at the site in 2003 (by ST). The analytical study (by LA) is of the medieval metallurgical debris excavated in 2002, mostly slag, but also ore and lead. The aim was to understand the raw material, the metal produced and the smelting process. The ore smelted was predominantly galena but with no detectable silver, showing it was probably exploited to produce lead. The extremely high sulphur content of the slag indicates that the ore was not roasted before smelting. It is argued that the medieval activity was small-scale, smelting a very rich ore. The furnaces apparently did not require much capital investment, enabling a short-lived and/or e...