A preliminary study on the role and implication of plate-type iron artifacts in the ancient iron technology of Korea

Special iron objects in the form of a narrow plate with a fan-shaped blade on one or both ends, but with a substantial variation in shape and size, have continually been excavated from ancient historical sites located in the southern part of the Korean peninsula. The frequency and abundance of their excavation imply that they must have played a crucial role in the initial shaping of the Korean iron industry. Little is known, however, of their intended purposes or the exact engineering processes applied in their production. Speculation suggests that they might have been used as currencies or intermediate materials for the making of finished products. This study examined the microstructures of three such iron objects from the Korean Three Kingdoms Period (ca. 300–600 AD). It was determined that they were made of low carbon iron generally containing a number of non-metallic inclusions, with hints of surface carburization particularly at the ends of the plates. These results reveal the likely presence of an iron technology based primarily on the bloomery technique as opposed to the Chinese style of iron-making based on cast iron technology, which was also in use in ancient Korea.     

Early use and production of iron in the northern Shaanxi: A perspective on iron objects excavated from the Yuejiazhuang cemetery site

Yuejiazhuang is a cemetery site of Qin people in the Northern Shaanxi, China, and it is dated to the mid-late Warring States Period. Ninety-two iron objects were excavated from the Yuejiazhuang cemetery site, which provide an opportunity to understand the use and production of iron in the Northern Shaanxi. The metallurgical and statistical study has revealed that bloomery iron, cast iron, and steel made from cast iron were adopted in the Northern Shaanxi during the mid-late Warring States Period. In the meanwhile, cast iron and steel made from cast iron became dominant in the Northern Shaanxi.     

Technological traditions inferred from iron artefacts of the Xiongnu Empire in Mongolia

Iron objects excavated from sites of the Xiongnu Empire (3rd century BC–2nd century AD) in Mongolia have been examined using optical and scanning electron microscopy. The results show that the Xiongnu iron tradition may be characterized by the use of low carbon iron and carbon control by carburization. Cast iron was also used in the Xiongnu Empire, but only in very limited applications and with no convincing evidence of its use for the production of low carbon iron. The Xiongnu iron technology seems to have been established on the basis of the bloomery technique, without much influence from the Chinese style of technology, based on cast iron.     

Investigating the production provenance of iron artifacts with multivariate methods

The quest for suitable data, data treatments and statistical methods for identifying the provenance of iron artifacts has led to a variety of analytical strategies. Researchers working on the problem have been slow to develop or adopt the use of multivariate statistical techniques, despite their successful implementation in other archaeomaterials sourcing frameworks. This paper explores the analytical potential of a comprehensive multivariate statistical strategy for identifying the primary production origins of bloomery iron artifacts using bulk chemical analyses of bloomery smelting slag and slag inclusions in iron artifacts. This strategy includes a multivariate model for identifying distinct slag inclusion types introduced during smelting and refining. Principal component analysis and linear discriminant analysis are then applied to smelting slag training sets to create multivariate provenance fields, the chemical distributions of which are defined by kernel density estimation. Single and multi-group evaluation methods are examined. Appropriate data transformations are discussed to facilitate the projection of the chemistry of “unknown” slag inclusions into the multidimensional space generated by the smelting slag groups of known provenance. The efficacy of this strategy is demonstrated through its application to a previously examined data set derived from three iron production experiments and a published archaeological example. Results indicate that an appropriately designed multivariate strategy can be an effective tool for evaluating provenance hypotheses for bloomery iron artifacts.     

Explaining the evolution of ironmaking recipes – An example from northwest Wales

Building on insights from previous Darwinian studies of technology, this paper explores the potential of evolutionary models to explain diversity and change in bloomery ironmaking recipes. Bloomery, or direct process ironmaking, involves the solid state reduction of iron oxide to metal and was the predominant means of producing iron in the pre-industrial world. The most archaeologically accessible record of bloomery practice is slag, an essential by-product of the smelting process. Ironmaking recipes can be characterized by their slag chemistry using a combination of multivariate statistics, ternary phase diagrams, and oxide ratios. Models derived from evolutionary theory are used to explain the shape, structure, and trajectories of ironmaking lineages identified from patterns of slag chemistry in terms of invention, selection, and socially mediated constraint processes. The utility of this approach is demonstrated by its application to slag excavated at Llwyn Du, a late medieval bloomery in northwest Wales.     

鲁山望城岗冶铁遗址的冶炼技术初步研究

本文通过对河南鲁山望城岗,台铁遗址出土和采集的冶铁遗物的综合分析,证明该遗址是个集冶炼、铸造和炼钢为一体的大型工场,持续时间较长,具体工艺表现为采用选好的褐铁矿在高炉中炼出生铁,然后铸成器物,存在脱碳制钢的处理工艺,并且在冶炼时可能使用了煤炭作为燃料。     

Using mineral magnetism to characterise ironworking and to detect its evidence in peat bogs

An experimental approach has been used to establish whether medieval ironworking activity could be identified in peat bogs using mineral magnetic measurements. The research project comprised three elements. First, magnetic susceptibility and remanence properties were obtained for materials from an experimental iron smelt, in a furnace of medieval design, and from material collected during the excavation of the medieval bloomery at Llwyn Du in Coed y Brenin, Snowdonia. Materials sampled and measured included charcoal, aerial dust, roasted bog ore and furnace dust. A second experiment determined whether small amounts of aerial dust released from the furnace could be detected in accumulating peat samples. This was achieved by sprinkling small quantities of dust on to a constructed ’peat core’ that had no detectable magnetic signature prior to the addition of the dust. The application rates used were within the range expected to fall on a peat bog located close to a medieval furnace. Thirdly, mineral magnetic measurements were made on a peat core collected close to the Llwyn Du bloomery. The results confirm that roasted bog ore, aerial dust released from and dust accumulating in the furnace after a smelt, are magnetically detectable. The aerial dust and roasted bog ore produced enhanced susceptibility and remanence signatures in the constructed ’peat core’ experiments. Peaks in IRM_(0.88T) and HIRM were measured in the Llwyn Du peat monolith and appear to correlate with a time when the medieval bloomery was operational. The results presented here suggest that it is possible to identify evidence of past ironworking in peat bogs using mineral magnetic measurements and that the signatures remain well preserved in the peat record even after burial for several hundred years.     

Iron and bronze production in Iron Age IIA Philistia: new evidence from Tell es-Safi/Gath, Israel

A metallurgically-oriented excavation in Area A at Tell es-Safi/Gath yielded evidence for iron and bronze production dating to the early Iron Age IIA. Two pit-like features, which differed considerably from one another in colour, texture and content, were excavated. Evidence shows that each feature represents a different in situ activity related to iron production, inferred by the presence of hammerscales, slag prills and slag. An upturned crucible was found on top of one of the features. Analysis of the crucible slag showed that it was used for bronze metallurgy. Tuyères, both round and square in cross-section, were found in and around the two features. The presence of the two industries together presents a unique opportunity to explore the relationship between copper and iron working. This is especially important against the background of the scarcity of evidence for iron production in the Levant during the early phases of the Iron Age.     

汉诸侯王陵墓出土铁器的比较

对徐州狮子山西汉楚王陵、永城保安山西汉梁王墓等7座汉王陵出土铁器的种类、材质、制作技术及功能进行了比较研究,探讨了汉代钢铁技术的发展状况、技术特征等问题。狮子山楚王陵5件炒钢制品的发现表明西汉早期(公元前2世纪中叶）已经发明了炒钢技术,是迄今为止最早的;块炼铁、块炼渗碳钢、生铁、铸铁退火、铸铁脱碳钢、炒钢、局部淬火、冷加工等多种钢铁冶炼和热处理工艺在西汉王陵出土铁器中都得到了广泛的应用,表明西汉时期钢铁技术有了较大发展,当时工匠对钢铁性能的认识提高到新的水平。     

Excavations at Rockley Smithies,a water-powered bloomery of the 16th and 17th Centuries

Abstract

Between about 1500 and 1640 iron was smelted by the direct, bloomery, process on the lands of the Rockley family at (N.G.R.) SE/340023, to the south-west of Barnsley, Yorkshire, using charcoal and ore from the well-wooded outcrops of the Tankersley ironstone, adjacent to the site. Evidence for operation early in the 16th century was limited to accumulations of hearth-cinder and of debris from ore-roasting, minor structures and traces of a dam. About 1600 a major rebuilding involved the construction of a bloom-hearth and probably two stringhearths, with bellows powered by waterwheels, and an unpowered hammer. Minor rebuilding took place early in the 17th century, and archaeological and documentary evidence combine to place abandonment at about 1640. Demolition and stone-robbing could well have provided material for the blast-furnace built a short distance away in 1652. The bloomery site was abandoned to pasture and perhaps a cottage, and at some time early in the 19th century was occupied by two houses and a workshop for an adjacent colliery tramway. It was covered by a road embankment in 1966.

Evidence was found of techniques at a comparatively advanced bloomery, in operation at a time when English ironmasters were, however, increasingly favouring the use of the blast furnace.     

TOOLS TO QUALIFY EXPERIMENTS WITH BLOOMERY FURNACES*

Five experimental bloomery iron ore smelts were carried out in a reconstruction of an early medieval furnace of the Boécourt type (Switzerland). A part of the bloom from the most successful experiment was forged to a billet. Starting materials and products were weighed, described and chemically characterized (ICP-MS, LA-ICP-MS and WD-XRF). The calculation of the yield and mass balance based on the chemical analyses from the ore (optimum) and from the ore, furnace lining, slag and ash (applied) allow the determination and quantification of the materials involved in the process. This permits the interpretation of the quality of the experiments. The chemical characterization of metal produced from hematite ore from the Gonzen Mountains in Switzerland gives archaeologists the possibility to compare the metal of iron artefacts to metal from this mine. Finally a good agreement between experiments and archaeological reality can be shown.     

战国秦汉时期制铁耐火材料的矿物组织与含量分析

战国秦汉时期是中国古代生铁与生铁制钢技术体系的发端与形成期,制铁耐火材料为发达的生铁与生铁制钢技术体系提供了结构、化学、热性能上的技术保障,具有重要的作用。但目前制铁耐火材料的研究较少,影响了对中国古代钢铁技术的全面认识。本研究对战国秦汉时期出土的制铁耐火材料开展了文献、田野考察和矿相分析,科学认知其微观结构,认为战国秦汉时期制铁耐火材料以黏土质材料为主,使用了砂质材料,但尚未出现砂泥混合质材料。同时,炉壁、铸铁范、鼓风管之间的矿物显微组织和含量差异较大,表明战国秦汉时期工匠已能根据性能需求的不同制作不同的耐火材料用于不同的制铁生产环节。     

Does it come from the Pays de Bray? Examination of an origin hypothesis for the ferrous reinforcements used in French medieval churches using major and trace element analyses

A new methodology based on major and trace element analyses of slag inclusions is proposed to determine (or exclude) the provenance of iron artefacts. It is applied to verify if the Pays de Bray, a French area between Rouen and Beauvais, could have been an important supplier for the ferrous reinforcements used in the Middle Ages for the building of churches and cathedrals in these two towns. To this purpose, the behaviour of trace elements during both direct and indirect operating chains is studied combining experimental smelting and different analytical methods, such as SEM–EDS, ICP–MS, LA–ICP–MS and INAA, performed on archaeological samples. The chemical signature of the Pays de Bray iron ore and slag is determined considering MnO and P₂O₅ contents as a first rough filter and seven couples of trace elements. Then, the major and trace elements are analysed using the same methods in the slag inclusions of 32 artefacts from the Beauvais and Rouen churches, made by the bloomery process. The trace element signature of the inclusions from each artefact is compared with the ore from the Pays de Bray area. The iron used in the Rouen and Beauvais churches seems not to come mainly from the Pays de Bray.     

The implication of the metallurgical traditions associated with Chinese style wagons from the royal Xiongnu tomb at Golmod 2 in Mongolia

Lavishly decorated wagons excavated from royal Xiongnu burials are generally regarded as tribute items from China offered to Xiongnu elites, symbolizing important political and economic interactions between the Xiongnu state (209 BC–155 AD) and the Han dynasty (206 BC–220 AD). This theory views such vehicles as having no relation to indigenous Xiongnu craftsmanship. Furthermore, specialized products delivered to the northern nomadic peoples from the Han state are often cited in support of the notion of Xiongnu dependency on foreign states for technological and political development. Expecting to find evidence of China’s traditional iron and bronze technology, we examined a number of key metallic components of these wagons excavated from the royal Xiongnu burial at Golmod 2 in central Mongolia, radiocarbon dated to 109 BC–AD 75. Surprisingly, the iron metallurgy in question was based primarily on the bloomery process while low tin bronze and arsenical copper alloys dominated the pertinent bronze production. These respective technological traditions are typical of Xiongnu manufacture but significantly different from traditional Han metallurgy. We interpret this evidence as suggesting the need for a more balanced evaluation of foreign influence on the rise and development of the Xiongnu state.     

METALLOGRAPHIC STUDY OF IRON ARTEFACTS FROM THE EASTERN TRANSVAAL,SOUTH AFRICA

The microstructures of two adzes, two hoes and a spear point from Iron Age settlement sites in the Kruger National Park have been examined. Electron microprobe analyses of the slag inclusions were also made. Some of the objects are made of high carbon steel while others have a highly variable carbon content. All appear to have been forged at relatively low temperature and then annealed at a low temperature near 700°C. None have been hardened by quenching and tempering. Some of the objects contain only traces of included slag while others have large slag inclusions. The slag compositions are quite different from those of medieval bloomery slags and are representative of African iron smelting practice in their high content of CaO, K₂ O and Na₂O. On the basis of the titanium content of the included slag, two of the objects are identified as made of the ore from Rooiwater and one from Phalaborwa ore.     

Mineralogical and geochemical characterization of high-medieval lead–silver smelting slags from Wiesloch near Heidelberg (Germany)—an approach to process reconstruction

Here, we present detailed electron microprobe analyses and age data of high-medieval lead–silver smelting slags. The mineral composition data provide a database of all silicate and oxide phases in the slag. Bulk chemistry as well as mineral composition is used to reconstruct liquidus, solidus, and viscosity of the slag melt. By calculating the mass balance of the smelting process, a mass ratio of the various compounds used in the smelting process is determined. Through this we were able to discriminate qualitatively between non-ferrous metal smelting slags and bloomery slags. We also report a new type and process of silver production in which argentiferous galmei (zinc carbonate) was used as a main silver ore together with galena. The results indicate a sophisticated high-medieval smelting technology, in which a slag with a low liquidus and a low viscosity was created.     

Slag inclusions in iron objects and the quest for provenance: an experiment and a case study

Slag inclusions are found within most archaeological bloomery iron artefacts and are remainders of slag created during the smelting and smithing processes. Although they are widely believed to provide data with the potential for provenancing iron artefacts, previous slag inclusion studies have mostly proven inconclusive. The main aim of the work reported here is to analyse experimental smelting and smithing assemblages (including ore, furnace lining, fuel and slag), to compare these to slag inclusions in the resulting bloom and worked objects, and then explore the relationships between ore, slag and slag inclusions. This study has revealed that the composition of slag inclusions most closely relates to the smelting slag produced, whereas provenance to a specific ore would be difficult due to the chemical variability derived from furnace lining, fuel and any fluxes used. Some compounds in the slag inclusions are particularly affected during smithing of the artefact, i.e. those present in the sand flux and fuel used. However, trends are observed in the K₂O/MgO, MnO/SiO₂, Al₂O₃/SiO₂, Al₂O₃/MgO, Al₂O₃/K₂O and Al₂O₃/CaO ratios that allow comparison between slag inclusions and smelting slag in these experiments, and may therefore be used during other provenancing attempts. The knowledge gained from the experimental assemblages was subsequently applied to an archaeological case study, examining objects from the 900 Cal BC smithing site of Tel Beth-Shemesh, Israel and the 930 Cal BC smelting site of Tell Hammeh, Jordan. The analyses suggest that none of the artefacts examined derived from the Hammeh smelting system.     

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

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

Prehistoric iron production technologies in the Upper Thai-Malay Peninsula: metallography and slag inclusion analyses of iron artefacts from Khao Sam Kaeo and Phu Khao Thong

This article presents a preliminary attempt to characterise Upper Thai-Malay Peninsula prehistoric iron technologies based on assemblages from two recently excavated coastal sites: Khao Sam Kaeo and Phu Khao Thong. These are the earliest known sites involved in the early trans-Asian exchange that connected the eastern Indian Ocean to the South China Sea from the mid-first millennium bc. It is from this period that iron assemblages start appearing at both continental and insular Southeast Asian sites. Three models have been offered confronting an indigenous vs. Chinese or South Asian impetus for the introduction of iron metallurgy in Southeast Asia. These models are discussed in the light of the metallographic and compositional analyses of iron and slag assemblages from these two sites using optical microscopy, scanning electron microscopy with energy dispersive spectrometry, energy dispersive X-ray fluorescence and slag inclusion analysis techniques, together with other production materials from these and other contemporaneous Southeast Asian sites.     

Charcoal analysis of industrial fuelwood from medieval and early modern iron-working sites in Bilsdale and Rievaulx,North Yorkshire,UK: evidence for species selection and woodland management

Abstract

This paper presents the results of species diversity and dendrological analyses of archaeological charcoal excavated from medieval and early modern iron production sites in Bilsdale, and at Rievaulx in the neighbouring valley of Ryedale, North Yorkshire, UK. Standard methods of quantification are used to assess species diversity, sampling sufficiency and taxa presence. The assessment of dendrological features provides additional evidence for growth trends and cutting cycles analogous with cyclical woodland management, as well as environmental and growing conditions. Analysis of archaeological charcoal from four medieval bloomery furnace sites in Bilsdale, and from the site of the hammersmithy and blast furnace at the early modern iron works at Rievaulx, provide comparable data-sets which indicate a change in cutting practise and dominant species selection for industrial fuelwood occurred between the 12th- and mid-16th centuries AD. Results show that dominant species presence changed from an admixture of predominantly birch (Betula sp.) and hazel (Corylus avellana) sourced from small calibre branchwood and stemwood used in the medieval bloomery furnaces, to a dominant oak (Quercus sp.) presence from standard sources used at the Rievaulx iron works by the mid-16th century. Whilst it is uncertain whether this change in dominant species composition and the source of industrial fuelwood is related to changes in local availability, or the result of the technological transition to blast furnace processing which occurred at this time, estate records reveal a woodland management campaign was instigated to supply and maintain fuelwood supplies to the iron works at Rievaulx which coincides with the introduction of Tudor arboricultural legislation in the 1540s.