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Os isotopic ratios and trace element approaches were used to compare the signatures of ore and slag from different potential production sites located in eastern France and SouthWest Germany with the signature of artefacts from the end of... more
Os isotopic ratios and trace element approaches were used to compare the signatures of ore and slag from different potential production sites located in eastern France and SouthWest Germany with the signature of artefacts from the end of the first Iron Age. A set of 31 artefacts was tested, consisting of bipyramidal semi-products, chariot tires, blooms and other commodities. The complementarity of the two approaches is demonstrated. Bipartite bipyramidal semi-products made by assembling two crude masses of distinct origins are evidenced suggesting the existence of intermediate producing centres assembling products from different origins. Only the provenance of blooms and wheel-tires could be established as local. Two spheres of metal circulation were evidenced: prestige and local. Bipyramidal semi-products and chariot tires belong to different long distance distribution networks.
The dynamic technological characteristics and diverse cultural potential of iron make it one of the most influential materials for facilitating cultural transformation. Reconstructing how iron was managed is an important way to understand... more
The dynamic technological characteristics and diverse cultural potential of iron make it one of the most influential materials for facilitating cultural transformation. Reconstructing how iron was managed is an important way to understand political and socioeconomic issues in pre-modern state-level societies. In contrast to studies of smelting sites, the study of iron objects allows us to evaluate trends of production in relation to practice of consumption. By investigating a given class of iron objects, it is possible to document shifts in technical processes, cultural choices, and social organisation that are representative of a state or polities broader iron economy. This study outlines the use of comprehensive archaeometallurgical typology, a new approach combining technological, chronological, and “sourcing” analyses of iron architectural crampons from the Khmer capital of Angkor (ninth to fifteenth c. CE) in Cambodia. Our methodology was implemented on 69 iron crampons from three masonry complexes (the Royal Palace, Baphuon, and Preah Khan) spanning the tenth to thirteenth centuries. Compiling a vast and statistically significant data set enables us to identify diachronic changes of production and manufacturing patterns that seem to be linked to key periods of expansion of the Khmer Empire. These patterns represent the first phase in reconstructing the iron economy of the most influential polities in mainland Southeast Asia.
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The dynamic technological characteristics and diverse cultural potential of iron make it one of the most influential materials for facilitating cultural transformation. Reconstructing how iron was managed is an important way to understand... more
The dynamic technological characteristics and diverse cultural potential of iron make it one of the most influential materials for facilitating cultural transformation. Reconstructing how iron was managed is an important way to understand political and socioeconomic issues in pre-modern state-level societies. In contrast to studies of smelting sites, the study of iron objects allows us to evaluate trends of production in relation to practice of consumption. By investigating a given class of iron objects, it is possible to document shifts in technical processes, cultural choices, and social organisation that are representative of a state or polities broader iron economy. This study outlines the use of comprehensive archaeometallurgical typology, a new approach combining technological, chronological, and Bsourcing^ analyses of iron architectural crampons from the Khmer capital of Angkor (ninth to fiftee nth c. CE) in Cambodia. Our methodology was implemented on 69 iron crampons from three masonry complexes (the Royal Palace, Baphuon, and Preah Khan) spanning the tenth to thirteenth centuries. Compiling a vast and statistically significant data set enables us to identify diachronic changes of production and manufacturing patterns that seem to be linked to key periods of expansion of the Khmer Empire. These patterns represent the first phase in reconstructing the iron economy of the most influential polities in mainland Southeast Asia.
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La construction du beffroi de la ville de Metz (Moselle, France), entre 1478 et 1483, a nécessité l'utilisation de plusieurs centaines de renforts ferreux afin de contribuer à la cohésion de la maçonnerie. Ce chantier se déroule à un... more
La construction du beffroi de la ville de Metz (Moselle, France), entre 1478 et 1483, a nécessité l'utilisation de plusieurs centaines de renforts ferreux afin de contribuer à la cohésion de la maçonnerie. Ce chantier se déroule à un moment particulier de l'histoire de la sidérurgie européenne, marqué par la diffusion du procédé indirect. Cette filière technique est adoptée graduellement par les producteurs de métal, définissant un panorama sidérurgique particulièrement riche et varié, dont l'étude enrichit notre perception de l'histoire de l'économie et des techniques métallurgiques. Une étude archéométrique extensive a été réalisée sur les renforts et leurs scellements en plomb afin de déterminer les origines technique et géographique du fer utilisé. L'exploitation des données chimiques obtenues a nécessité l'utilisation de plusieurs analyses statistiques multivariées afin de mieux comprendre l'histoire de l'édifice, d'évaluer l'importance du fer produit par procédé indirect sur les marchés du fer lorrains de la fin du Moyen Âge, et d'identifier les acteurs sidérurgiques engagés dans l'approvisionnement des réseaux d'échange. Cet article présente les étapes successives de l'étude réalisée, en détaillant pour chacune les facteurs qui ont motivé le recours à différentes analyses statistiques multivariées (analyse en composantes principales, classification ascendante hiérarchique, régression logistique), ainsi que les principaux résultats obtenus. Abstract: The building of the belfry of Metz (Lorraine, France), which took place between 1478 and 1483, necessitated the implementation of hundreds of ferrous reinforcements to contribute to the cohesion of the masonry. This building yard took place at a particular time in the history of the European siderurgy, marked by the diffusion of the finery process. This technical innovation has been gradually adopted par iron producers, drawing up a particularly rich and diverse panorama, whose study enrichises our knowledge of the history of metallurgical techniques and economy. An extensive archaeometrical study was carried out on the reinforcements and their lead sealings in order to determine the technical and geographical origins of the iron. The processing of the chemical data that was obtained required the use of several multivariate statistical analyses to better understand the chronology of the monument, to evaluate the importance of the finery process in the supply of the iron markets set up in late medieval Lorraine, and to identify the iron producers involved in providing the exchange networks. This paper presents the successive stages of the study, by detailing for each step the factors that have required the use of different multivariate statistical analyses (principal component analysis, hierarchical clustering, logistic regression), as well as the major results obtained.
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Durant les premiers temps de la métallurgie du fer en Europe occidentale, le type de demi-produit le plus répandu est de forme bipyramidée. Bien que plus d'un millier de pièces soit connu, leurs conditions de fabrication et de circulation... more
Durant les premiers temps de la métallurgie du fer en Europe occidentale, le type de demi-produit le plus répandu est de forme bipyramidée. Bien que plus d'un millier de pièces soit connu, leurs conditions de fabrication et de circulation et même leur datation restent mal appréhendées Une approche interdisciplinaire a ainsi été appliquée au dépôt de demi-produits bipyramidés de Durrenentzen (Haut-Rhin), le troisième en Europe par son importance numérique, afin de reconstituer le contexte technologique, social et économique qui a conduit à son abandon. L’étude morphométrique des cinquante-et-un bipyramidés révèle une grande homogénéité globale du lot malgré des variations de détail. Quatre objets ont été sélectionnés pour études archéométriques. Les analyses métallographiques mettent en évidence des différences internes significatives en ce qui concerne la qualité des matériaux, la nature de l’alliage et les techniques de fabrication. Les analyses chimiques révèlent également des signatures différenciées. Enfin, des analyses radiocarbones réalisées sur le carbone contenu dans les aciers permettent de rattacher ce lot au premier âge du Fer. Les résultats de l’étude de ce dépôt exceptionnel permettent ainsi d’implanter le premier jalon d’une analyse plus générale modifiant significativement la perception de l’économie du fer au premier âge de Fer.
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A rescue excavation has unearthed the remains of a bridge crossing the Moselle River at Dieulouard (Meurthe-et-Moselle, France). This constitutes one of the rare examples of non-religious monumental architecture from the Carolingian... more
A rescue excavation has unearthed the remains of a bridge crossing the Moselle River at Dieulouard (Meurthe-et-Moselle, France). This
constitutes one of the rare examples of non-religious monumental architecture from the Carolingian period in France. The present archaeometrical study, conducted on a set of architectural iron fastenings, provides an opportunity to examine the modalities through which early medieval
building yards acquired ferrous materials. Located within the vicinity of active ironmaking zones, a hypothesis was subsequently put forward that the iron supply was provided by a local market. The results nevertheless highlight a more complex acquisition strategy than expected, relying at least partially on metal salvaging. This study therefore stimulates current discussions of the importance of recycling in the Carolingian economy, and of the value attributed to material and its transformation.
constitutes one of the rare examples of non-religious monumental architecture from the Carolingian period in France. The present archaeometrical study, conducted on a set of architectural iron fastenings, provides an opportunity to examine the modalities through which early medieval
building yards acquired ferrous materials. Located within the vicinity of active ironmaking zones, a hypothesis was subsequently put forward that the iron supply was provided by a local market. The results nevertheless highlight a more complex acquisition strategy than expected, relying at least partially on metal salvaging. This study therefore stimulates current discussions of the importance of recycling in the Carolingian economy, and of the value attributed to material and its transformation.
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This paper develops new reflections regarding the provenance of iron artefacts, by defining the trade networks that might have supplied the building yard of the Metz city belfry at the end of the fifteenth century. Regional field surveys... more
This paper develops new reflections regarding the provenance of iron artefacts, by defining the trade networks that might have supplied the building yard of the Metz city belfry at the end of the fifteenth century. Regional field surveys were carried out in Lorraine in order to constitute a chemical repository, including ironmaking zones considered as the most probable metal providers. The chemical characterization –both major and trace elements – of slag inclusions entrapped in iron reinforcements' metallic matrix was performed in order to compare their chemical signature to the reference set. A statistical approach based on the combined use of descriptive multivariate analyses was developed to infer the origin of the metal supplied to the building yard. As the multiplicity of potential metal providers was assessed from former studies, the results obtained underline the place taken by local workshops in the supplying strategy developed by the builders. This study thus provides crucial information supporting a discussion about the scale and the organization of such networks at the end of the Middle Ages.
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Lead was a broadly used metal in ancient times, especially for construction purposes. The potential of construction lead analysis has never been considered so far, as most analytical methods prove restrictive to study large sets of... more
Lead was a broadly used metal in ancient times, especially for construction purposes. The potential of construction lead analysis has never been considered so far, as most analytical methods prove restrictive to study large sets of samples. For this purpose, the development of a new lead analytical protocol using LA-ICP-MS was undertaken. It can determine quickly at the ppm level for the main trace elements contained in ancient lead alloys: As, Ag, Bi, Cd, Cu, Ni, Sb, and Sn. The method was then applied to a set of 172 lead sealings sampled on three major cathedrals of Gothic France: Bourges, Chartres and Metz. Results show that no particular lead quality was required for construction on these building yards and that the final composition of the lead depends on the definitive mixing of matters before pouring. Regarding this last point, for each monument, discrimination of different “melt batches” of lead through trace element analysis was able to highlight unprecedented chronological sequences, thus greatly improving our understanding of the building dynamics.
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A specific statistical approach was tested to determine the ironmaking processes (bloomery or indirect) used to manufacture iron reinforcements found in two French gothic medieval monuments: Metz and Beauvais Cathedrals. Slag inclusions... more
A specific statistical approach was tested to determine the ironmaking processes (bloomery or indirect)
used to manufacture iron reinforcements found in two French gothic medieval monuments: Metz and
Beauvais Cathedrals. Slag inclusions embedded in the metallic matrix were analysed and the major
element compositions were quantified, using a Si Drift EDS detector permitting the study of several
hundred inclusions per artefact. First, pre-processing was applied to the raw data to discriminate inclusions
from the smelting stage (or refining stage for the indirect process) from those formed during
post-reduction operations (forging etc.). PCA and hierarchical clustering on the major element compositions
were then performed. Secondly, a specific multivariate statistical method, logistic regression,
was applied to a learning set of data from a reference set of samples. This allowed the development of a
model capable of distinguishing artefacts from the two smelting processes and to link unknown samples
to one or the other. This model was then used to study artefacts from the Mutte Tower of Metz Cathedral
and Beauvais Cathedral. This allowed us to confirm the extensive use of iron reinforcements since the
construction of Beauvais cathedral. In the Mutte Tower of Metz Cathedral clamps from Lorraine reinforced
some parts of the monument from its construction between the 13th and the 15th centuries.
used to manufacture iron reinforcements found in two French gothic medieval monuments: Metz and
Beauvais Cathedrals. Slag inclusions embedded in the metallic matrix were analysed and the major
element compositions were quantified, using a Si Drift EDS detector permitting the study of several
hundred inclusions per artefact. First, pre-processing was applied to the raw data to discriminate inclusions
from the smelting stage (or refining stage for the indirect process) from those formed during
post-reduction operations (forging etc.). PCA and hierarchical clustering on the major element compositions
were then performed. Secondly, a specific multivariate statistical method, logistic regression,
was applied to a learning set of data from a reference set of samples. This allowed the development of a
model capable of distinguishing artefacts from the two smelting processes and to link unknown samples
to one or the other. This model was then used to study artefacts from the Mutte Tower of Metz Cathedral
and Beauvais Cathedral. This allowed us to confirm the extensive use of iron reinforcements since the
construction of Beauvais cathedral. In the Mutte Tower of Metz Cathedral clamps from Lorraine reinforced
some parts of the monument from its construction between the 13th and the 15th centuries.
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The Lorraine region is well-known as the most important ironmaking production area in France, mainly from the second half of the XIXth c. to the end of the XXth c., based on the exploitation of a sedimentary ore, the minette lorraine.... more
The Lorraine region is well-known as the most important ironmaking production area in France, mainly from the second half of the XIXth c. to the end of the XXth c., based on the exploitation of a sedimentary ore, the minette lorraine. This ore, containing relatively low amounts of iron, and some unwanted compounds, was considered as unworkable until the Thomas process’ conception in 1877. The booming of preventive archaeological excavations in the 1990’s decade permitted the unearthing of some large iron production sites in this region. Recent researches led on iron production in the Lorraine region have highlighted important ironworking activities, especially during early medieval times. Moreover, some important aspects concerning the exploitation of local ores were demonstrated, such as the effectiveness of smelting minette ore during ancient times, and the concomitant use of a siderolithic ore, called fer-fort.
Besides these substantial ancient ironmaking activities, the Lotharingia region also occupied a central position in the political context during early medieval times, especially during Merovingian and Carolingian eras. Some large thoroughfares also crossed this area, making it a potential nodal point in goods exchanges, including iron products. Thus the question of the trading dynamics concerning these products is asked.
Considering archaeological data the iron produced in Lorraine might have been exported, especially in neighboring regions. This study aims to determine the scale of the Lorraine iron production circulation. An approach, developed by the Laboratoire Archéomatériaux et Prévision de l’Altération, was applied to this study. It has been demonstrated that iron production systems’ geochemical signature could be tracked within iron products, applying a rigorous analytical protocol.
Considering questionings evoked about goods exchanges, it was aimed to determine whether a set of artifacts, unearthed in a local context, could be connected to the local iron production systems’ geochemical signature. A set of iron clamps, stemming from the stone piers of a medieval bridge dated to the beginning of the IXth c., was studied. Results were confronted to a geochemical reference set (PalSid database), containing data concerning the two major ore kinds in Lorraine, the minette and a siderolithic ore called fer-fort. It appeared that the chemical signatures of the clamps set didn’t match neither to the minette, nor to the fer-fort chemical domains, excluding the possibility that the iron composing these artifacts was produced using these ores. Moreover, different groups of chemical signatures could be observed within the clamps set, suggesting the eventuality of multiple origins.
The question of a local origin remains asked, because all kinds of iron ores in Lorraine aren’t yet chemically characterized. But the case of Dieulouard, the clamps of which presenting diverse chemical signatures, also suggests that the workshop which has produced the artifacts used a diverse set of iron, maybe recycled products. In order to answer these questions, it is planned to enrich the geochemical reference set by collecting ore and slag in other potential iron production sectors. In addition, siderurgical products and wastes from sites presenting smelting and smithing activities linked with a minette exploitation will be studied to supply more chemical data for iron products associated with the different operating steps. More artifacts sets, issued from local contexts will also be studied by the same analytical process employed for the Dieulouard clamps.
Besides these substantial ancient ironmaking activities, the Lotharingia region also occupied a central position in the political context during early medieval times, especially during Merovingian and Carolingian eras. Some large thoroughfares also crossed this area, making it a potential nodal point in goods exchanges, including iron products. Thus the question of the trading dynamics concerning these products is asked.
Considering archaeological data the iron produced in Lorraine might have been exported, especially in neighboring regions. This study aims to determine the scale of the Lorraine iron production circulation. An approach, developed by the Laboratoire Archéomatériaux et Prévision de l’Altération, was applied to this study. It has been demonstrated that iron production systems’ geochemical signature could be tracked within iron products, applying a rigorous analytical protocol.
Considering questionings evoked about goods exchanges, it was aimed to determine whether a set of artifacts, unearthed in a local context, could be connected to the local iron production systems’ geochemical signature. A set of iron clamps, stemming from the stone piers of a medieval bridge dated to the beginning of the IXth c., was studied. Results were confronted to a geochemical reference set (PalSid database), containing data concerning the two major ore kinds in Lorraine, the minette and a siderolithic ore called fer-fort. It appeared that the chemical signatures of the clamps set didn’t match neither to the minette, nor to the fer-fort chemical domains, excluding the possibility that the iron composing these artifacts was produced using these ores. Moreover, different groups of chemical signatures could be observed within the clamps set, suggesting the eventuality of multiple origins.
The question of a local origin remains asked, because all kinds of iron ores in Lorraine aren’t yet chemically characterized. But the case of Dieulouard, the clamps of which presenting diverse chemical signatures, also suggests that the workshop which has produced the artifacts used a diverse set of iron, maybe recycled products. In order to answer these questions, it is planned to enrich the geochemical reference set by collecting ore and slag in other potential iron production sectors. In addition, siderurgical products and wastes from sites presenting smelting and smithing activities linked with a minette exploitation will be studied to supply more chemical data for iron products associated with the different operating steps. More artifacts sets, issued from local contexts will also be studied by the same analytical process employed for the Dieulouard clamps.
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The Mutte tower, the belfry of the medieval city is one of the most emblematic buildings of Metz. Its construction began in the middle of the 13th c. and lasted until the end of the 15th c. with the building of the upper stories including... more
The Mutte tower, the belfry of the medieval city is one of the most emblematic buildings of Metz. Its construction began in the middle of the 13th c. and lasted until the end of the 15th c. with the building of the upper stories including a stone spire in a short and well documented campaign between 1478 and 1483. According to a widespread practice in medieval architecture, iron elements (clamps, studs, rods,…) sealed in lead alloy were used for masonry reinforcement. Former studies led on other medieval buildings have demonstrated that it was possible, by specific chemical analyses performed on artifacts, to determine iron sources, and to describe metal trading modalities (Leroy et al. 2012). As Lorraine is an important ironmaking area during the medieval times, this study first aims to determine if locally-produced iron was used by the tower’s building workshops. Moreover, a new ironmaking process (blast furnace & finery) spreads across Europe in the end of the Middle Ages. Determining whether iron artifacts of the Mutte tower were actually produced using this new process may enrich our perception of the quickness of its diffusion.
Unfortunately, the building sustained many depredations throughout modern and contemporary eras, which led to frequent local restoration works. As a result, numerous iron reinforcements are now visible on the tower’s facades, either medieval or modern. To ensure selection of the former, a specific data mining methodology, based on multivariate analyses of compositional data (Clustering analyses coupled to Principal Component Analyses), was developed. Results of cross queries performed on both compositional (iron elements and their lead sealing) and technical data were displayed using an intrasite GIS, in order to identify consistent patterns in ferrous reinforcements layout, which might most probably characterize building and restoration phases.
Once the artifact set sorted, a predictive statistical method, based on linear modeling, was applied in order to determine through which ironmaking process each sample was produced. This was performed on compositional data of slag inclusions trapped in the metal. Our study showed that both processes could be identified among the sample set, suggesting that the late 15th c. constitutes a transitive period in Lorraine in terms of ironmaking processes. Moreover it was demonstrated, by comparing the artifacts’ chemical signature to those of the local iron production centers, that some of the iron reinforcements were indeed produced in Lorraine, using Minette, a well-known sedimentary ore.
Unfortunately, the building sustained many depredations throughout modern and contemporary eras, which led to frequent local restoration works. As a result, numerous iron reinforcements are now visible on the tower’s facades, either medieval or modern. To ensure selection of the former, a specific data mining methodology, based on multivariate analyses of compositional data (Clustering analyses coupled to Principal Component Analyses), was developed. Results of cross queries performed on both compositional (iron elements and their lead sealing) and technical data were displayed using an intrasite GIS, in order to identify consistent patterns in ferrous reinforcements layout, which might most probably characterize building and restoration phases.
Once the artifact set sorted, a predictive statistical method, based on linear modeling, was applied in order to determine through which ironmaking process each sample was produced. This was performed on compositional data of slag inclusions trapped in the metal. Our study showed that both processes could be identified among the sample set, suggesting that the late 15th c. constitutes a transitive period in Lorraine in terms of ironmaking processes. Moreover it was demonstrated, by comparing the artifacts’ chemical signature to those of the local iron production centers, that some of the iron reinforcements were indeed produced in Lorraine, using Minette, a well-known sedimentary ore.
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Les travaux menés par le Laboratoire Métallurgies et Cultures sur les thématiques de la production et de la diffusion des objets ferreux ont permis l’élaboration et le développement continu d’une méthodologie exploitant la signature... more
Les travaux menés par le Laboratoire Métallurgies et Cultures sur les thématiques de la production et de la diffusion des objets ferreux ont permis l’élaboration et le développement continu d’une méthodologie exploitant la signature chimique des inclusions de scorie dans le métal. Ces inclusions constituent en effet les marqueurs chimiques des systèmes de production du fer, permettant de formuler des hypothèses sur la provenance des produits sidérurgiques. Des études précédentes ont pu montrer qu’une analyse des éléments majeurs de ces inclusions pouvait permettre de les relier aux systèmes de réductions utilisés pour l’obtention du métal (minerai, charbon et paroi).
Toutefois, les inclusions de scorie issues de la réduction ne sont pas les seules pouvant être présentes. D’autres, non liées chimiquement au système de réduction, peuvent être créées par des ajouts employés par le forgeron au cours des opérations consistant à épurer, puis mettre en forme le métal. Ainsi, nos efforts se concentrent actuellement sur la discrimination des différentes catégories d’inclusions dans le métal, notamment par l’emploi d’analyses à valeur statistiques. En effet, les derniers développements des détecteurs EDS et des systèmes d’analyse et de détection permettent à ce jour l’analyse de plusieurs centaines d’inclusions par coupe métallographique. Ceci ouvre la voie à la mise en place de méthodes de traitement des données basées à la fois sur une approche multivariée et sur des méthodes d’analyse statistiques telles que la classification hiérarchique et l’analyse en composante principales. Le but est, dans un premier temps de tester ces méthodes sur un lot d’artefacts issu de l’archéologie expérimentale.
Plusieurs campagnes d’expérimentation archéologique ont été menées, sur les plateformes expérimentales de Melle et de Nancy-Jarville, dans le but de mieux cerner l’influence d’ajouts de forge de natures différentes sur la signature chimique globale des inclusions. Nous avons également employé, en guise de matière première, du métal archéologique issu de différents stades de la chaîne opératoire, depuis les masses brutes de réduction jusqu’à des pièces déjà travaillées. Des échantillons ont été collectés lors de chaque séquence de travail, afin de pouvoir qualifier au mieux l’emploi d’ajout en fonction de la quantité de travail apportée à la mise en forme du métal. Les déchets métallurgiques liés à ces phases (culots de forge et battitures) ont également été collectés, afin de constituer un corpus de comparaison pour l’étude de déchets mis au jour en contexte archéologique.
Les analyses réalisées et l’emploi, sur ces produits expérimentaux, de techniques statistiques pour discriminer les différentes familles d’inclusions (réduction et forge) ont permis à la fois de valider les approches mais également de mieux comprendre l’effet de l’introduction d’ajouts dans le métal, et de quantifier plus précisément son influence sur la nature des inclusions obtenues. Elles ont également fourni des éléments de comparaison dans le cas de certaines observations réalisées par ailleurs sur des échantillons archéologiques. Ces travaux déboucheront sur la mise en place d’un référentiel qui sera exploité dans les prochaines années pour l’étude des objets et sites archéologiques de travail du fer.
Toutefois, les inclusions de scorie issues de la réduction ne sont pas les seules pouvant être présentes. D’autres, non liées chimiquement au système de réduction, peuvent être créées par des ajouts employés par le forgeron au cours des opérations consistant à épurer, puis mettre en forme le métal. Ainsi, nos efforts se concentrent actuellement sur la discrimination des différentes catégories d’inclusions dans le métal, notamment par l’emploi d’analyses à valeur statistiques. En effet, les derniers développements des détecteurs EDS et des systèmes d’analyse et de détection permettent à ce jour l’analyse de plusieurs centaines d’inclusions par coupe métallographique. Ceci ouvre la voie à la mise en place de méthodes de traitement des données basées à la fois sur une approche multivariée et sur des méthodes d’analyse statistiques telles que la classification hiérarchique et l’analyse en composante principales. Le but est, dans un premier temps de tester ces méthodes sur un lot d’artefacts issu de l’archéologie expérimentale.
Plusieurs campagnes d’expérimentation archéologique ont été menées, sur les plateformes expérimentales de Melle et de Nancy-Jarville, dans le but de mieux cerner l’influence d’ajouts de forge de natures différentes sur la signature chimique globale des inclusions. Nous avons également employé, en guise de matière première, du métal archéologique issu de différents stades de la chaîne opératoire, depuis les masses brutes de réduction jusqu’à des pièces déjà travaillées. Des échantillons ont été collectés lors de chaque séquence de travail, afin de pouvoir qualifier au mieux l’emploi d’ajout en fonction de la quantité de travail apportée à la mise en forme du métal. Les déchets métallurgiques liés à ces phases (culots de forge et battitures) ont également été collectés, afin de constituer un corpus de comparaison pour l’étude de déchets mis au jour en contexte archéologique.
Les analyses réalisées et l’emploi, sur ces produits expérimentaux, de techniques statistiques pour discriminer les différentes familles d’inclusions (réduction et forge) ont permis à la fois de valider les approches mais également de mieux comprendre l’effet de l’introduction d’ajouts dans le métal, et de quantifier plus précisément son influence sur la nature des inclusions obtenues. Elles ont également fourni des éléments de comparaison dans le cas de certaines observations réalisées par ailleurs sur des échantillons archéologiques. Ces travaux déboucheront sur la mise en place d’un référentiel qui sera exploité dans les prochaines années pour l’étude des objets et sites archéologiques de travail du fer.
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Precedent studies (Leroy 1997) have high-lighted the scale of iron-production activities in Lorraine during the Middle Ages, and especially for the early medieval period. According to archaeological data, those activities seem to have... more
Precedent studies (Leroy 1997) have high-lighted the scale of iron-production activities in Lorraine during the Middle Ages, and especially for the early medieval period. According to archaeological data, those activities seem to have benefitted of very important iron ore deposits, and specifically a particular one, the Minette Lorraine. For this context, the iron production organization was well studied last years through archaeometallurgical works led on some production sites. Nevertheless, the becoming of the metal produced is not yet documented. The question of its spreading modalities remains open. The scale of iron distribution circuits remains unknown for this area. Moreover, although some textual data evoke some metal quantities produced in several sectors for the late medieval period, the relative importance of the different production zones in Lorraine during ancient times is not defined for now.
The work presented aims to treat these questions by complementary approaches. Following the way given by the studies of S. Leroy (Leroy et al. 2011), a geochemical approach which consists in establishing the chemical signature of the production area by performing major and trace analyses using ICP-MS on ore and smelting slag samples is applied. Then, to establish a link between resources and products, representative iron production sites have to be studied by archaeometallurgical studies. To do so, a specific methodology, mainly based on metallographic examinations and chemical analyses led on artifacts samples stemming from consumption sites, is developed. Different metallurgical wastes categories from production sites are studied. Experimental protocols were established to refine archeological interpretations. Confronted to this reference data set, artifacts from consumption sites, such as the Metz Cathedral and a Carolingian bridge, are studied following a process including macroscopic and microscopic analyses, the latter coupled with metallographic observation, followed by chemical analyses for major (SEM-EDS) and trace (LA-ICP-MS) elements.
First results show that the main types of iron ore, and therefore the main iron production zones in Lorraine, can be globally discriminated from each other on a chemical point of view, particularly using statistical multivariate approaches. Moreover, the study of a reference site presenting remains related to both smelting and smithing stages in a Minette-smelting context allowed characterizing the evolution of the original chemical signature during all different operating steps. These observations let us expect, despite an increase of the variability of the signature along the operating chain, that a reliable chemically-based discriminating tool could be developed to evaluate the iron products’ spreading in the area considered.
LEROY, M., 1997. La Sidérurgie en Lorraine avant le haut fourneau. L’utilisation du minerai de fer oolithique en réduction directe. CNRS Ed., 302 p.
LEROY, S., COHEN, S.X., VERNA, C.,Gratuze, B., TÉREYGEOL, F, FLUZIN, P., BERTRAND, L., DILLMANN, P., 2011. The medieval iron market in Ariège (France). Multidisciplinary analytical approach and multivariate analyses. Journal of Archaeological Science. In press.
The work presented aims to treat these questions by complementary approaches. Following the way given by the studies of S. Leroy (Leroy et al. 2011), a geochemical approach which consists in establishing the chemical signature of the production area by performing major and trace analyses using ICP-MS on ore and smelting slag samples is applied. Then, to establish a link between resources and products, representative iron production sites have to be studied by archaeometallurgical studies. To do so, a specific methodology, mainly based on metallographic examinations and chemical analyses led on artifacts samples stemming from consumption sites, is developed. Different metallurgical wastes categories from production sites are studied. Experimental protocols were established to refine archeological interpretations. Confronted to this reference data set, artifacts from consumption sites, such as the Metz Cathedral and a Carolingian bridge, are studied following a process including macroscopic and microscopic analyses, the latter coupled with metallographic observation, followed by chemical analyses for major (SEM-EDS) and trace (LA-ICP-MS) elements.
First results show that the main types of iron ore, and therefore the main iron production zones in Lorraine, can be globally discriminated from each other on a chemical point of view, particularly using statistical multivariate approaches. Moreover, the study of a reference site presenting remains related to both smelting and smithing stages in a Minette-smelting context allowed characterizing the evolution of the original chemical signature during all different operating steps. These observations let us expect, despite an increase of the variability of the signature along the operating chain, that a reliable chemically-based discriminating tool could be developed to evaluate the iron products’ spreading in the area considered.
LEROY, M., 1997. La Sidérurgie en Lorraine avant le haut fourneau. L’utilisation du minerai de fer oolithique en réduction directe. CNRS Ed., 302 p.
LEROY, S., COHEN, S.X., VERNA, C.,Gratuze, B., TÉREYGEOL, F, FLUZIN, P., BERTRAND, L., DILLMANN, P., 2011. The medieval iron market in Ariège (France). Multidisciplinary analytical approach and multivariate analyses. Journal of Archaeological Science. In press.