Papers on copper and its alloys by Siran Liu
Journal of Archaeological Science, 2020
Micro-slag artefacts from ancient bronze casting workshops were largely ignored in previous resea... more Micro-slag artefacts from ancient bronze casting workshops were largely ignored in previous research despite their rich information potential. Current research demonstrates they could significantly enhance our understanding about past metallurgical activities but their identification requires careful in-situ analysis and a well-designed sampling strategy. Here we present an innovative methodology combining in-situ geochemical survey , wet-sieving of soil samples and detailed microscopic study, employed to investigate an important Middle-Shang site, Taijiasi, in the Huaihe River valley. The micro-slags from this site revealed that in addition to bronze alloying and casting, raw copper refining was also practiced. Material evidence for the refining process was not immediately visible in the archaeological excavation since most slag was mechanically crushed to retrieve any copper trapped in them, leaving only micro-slag fragments typically smaller than 3000 μm (3 mm). The fact that most micro-slag was recovered from one sector (H234) of a small building (F16) located on the same platform as the elites' long houses suggests that mechanical processing of refining slag was conducted in a confined area and closely supervised. It might reflect people of this site valuing copper as a highly precious material and making all effort to recover copper otherwise lost in slag. This find will potentially shed new light on a range of important issues of Shang archaeology, including the regional variation of Shang metallurgical styles and the provenance of copper in the Shang period. This research also encourages researchers to look into archaeological soil samples with abnormally high copper content and understand the particles in them causing these high readings.
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In this brief response to Sun et al.'s (2018) comments on our paper, we re-emphasize that archaeo... more In this brief response to Sun et al.'s (2018) comments on our paper, we re-emphasize that archaeological , chemical and isotopic evidence are all relevant to the discussion about the metal source of the Shang period with highly radiogenic lead isotope ratios. The southern African bronzes have much lower lead contents and quite different lead isotopic signatures than the Shang bronzes. More importantly, there was no metallurgy of any kind in southern Africa before c.200 CE, so southern Africa cannot possibly be the source of Shang bronze, which date to about 1500 to 1000 BCE.
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Previous archaeometallurgical studies on Bronze Age China mainly focused on finished artefacts, w... more Previous archaeometallurgical studies on Bronze Age China mainly focused on finished artefacts, whereas our understanding of copper smelting technology of this period is still limited. This paper, for the first time, presents analytical results of metal production remains from the site of Laoniupo in Guanzhong Plain, central Shaanxi. It reveals that arsenical copper was produced at this site by smelting arsenic-rich polymetallic ores with raw copper or high purity copper ores. The identification of metal production in the Guanzhong Plain is significant for the investigation of regional development and interregional interaction of Bronze Age cultures in China. The possible exploitation of ores from deposits in the Qinling Mountain region during this period is also discussed in this article.
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The origins of the copper, tin and lead for China's rich Bronze Age cultures are a major topic in... more The origins of the copper, tin and lead for China's rich Bronze Age cultures are a major topic in archaeological research, with significant contributions being made by archaeological fieldwork , archaeometallurgical investigations and geochemical considerations. Here, we investigate a recent claim that the greater part of the Shang-period metalwork was made using metals from Africa, imported together with the necessary know-how to produce tin bronze. A brief review of the current status of lead isotopic study on Shang-period bronze artefacts is provided first, clarifying a few key issues involved in this discussion. It is then shown that there is no archaeological or isotopic basis for bulk metal transfer between Africa and China during the Shang period, and that the copper and lead in Shang bronze with a strongly radiogenic signature is not likely to be from Africa. We call for collaborative interdisciplinary research to address the vexing question of the Shang period's metal sources, focusing on smelting sites in geologically defined potential source regions and casting workshops identified at a number of Shang settlements.
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Journal of Archaeological Science 53, 2015
Very little is known about early metallurgical activity in the north-western part of the Arabian ... more Very little is known about early metallurgical activity in the north-western part of the Arabian Peninsula, despite the region's cultural importance. To begin to address this research lacuna, metallurgical remains including crucible fragments, metal dross and a copper artefact were sampled from two oases in northwest Arabia, Qurayyah and Tayma. The metallurgical activity in Qurayyah is dated to the Late Bronze Age, and in Tayma to the Roman/Late Roman period. At both sites we identified evidence for copper alloying and refining. Small scale copper smelting might also have been practiced in Qurayyah. Arsenical copper was processed at both sites, but in Tayma tin bronze and leaded tin bronze dominated. The chemical analysis of metal prills in crucible linings showed that fresh copper and tin instead of scrap metal were employed in these processes. Lead isotope analysis indicates that at least some of the Tayma metal was imported. Access to raw materials from remote areas is consistent with the importance of Tayma in the trading network of northwest Arabia.
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Lead/silver smelting by Siran Liu
Journal of Archaeological Science, 2019
Silver was an important metal in the economy of imperial China. However, until now, research on s... more Silver was an important metal in the economy of imperial China. However, until now, research on silver production technology in its social-economic and environmental contexts has been limited. Here we present a unique silver-lead production site in Hebei province, north China, dated between the 12th and 13th century AD, yielding vast numbers of slag-filled tubular crucibles and coal-ash slag chunks. Microstructural and chemical analysis reveals the crucibles were manufactured from refractory clays and that the slag inside contains lead-silver particles, un-reacted ore and numerous fragments of metallic iron. These finds indicate that the crucibles were used for smelting argentiferous sulphidic lead ores, which were reduced to metal by desulphurization using metallic iron. Mineral coal was employed to fuel this process from outside the crucibles. The use of mineral coal and externally-fired crucibles for smelting was an important technological innovation, but not one that could be adopted by all industries. We argue that it was most likely associated with rampant deforestation and the fuel crisis historically documented for the early second millennium in northern China. Contrary to received wisdom, this study demonstrates that the early adoption of coal was not as widespread as typically assumed, as it required a range of technological innovations. Crucible smelting, as one of the solutions, was embraced by lead-silver smelters, while most iron smelters in this period still persisted with the charcoal-fired furnace smelting tradition.
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The site of Baojia is located in the central part of the Shangrao county , 5km to the south of Xi... more The site of Baojia is located in the central part of the Shangrao county , 5km to the south of Xinjiang River. Since 2009 , archaeologists have conducted several field investigations at this site , and identified a mining and a smelting districts. The site is preliminarily dated to the Tang-Song period and was possibly used in the later period as well. The ore used at this site was vein gold with most gold bearing particles trapped in the silicate matrix , which had to be smelted with a pyro-technology. Additionally , the silver content of the Baojia ore and slag is significant , indicating that both gold and silver were extracted at this site. The relatively low lead content in the Baojia ore negatively affected the silver extraction efficiency. It is argued that the small production scale and low degree of specialisation caused Baojia smelters to be reluctant to import extraneous lead to promote their yield of silver. The study of this site enhanced our understanding about the vein gold mining and pyro-technology of gold and silver smelting in imperial China. Meanwhile , it also demonstrates the strength of combining textual research , archaeological investigation and scientific analysis in the study of ancient metal production sites .
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Technical ceramic by Siran Liu
Scientific Reports, 2021
Intricate ceramic bronze-casting moulds are among the most significant archaeological remains fou... more Intricate ceramic bronze-casting moulds are among the most significant archaeological remains found at Bronze Age metallurgical workshops in China. Firing temperature was presumably one of the most important technical factors in mould making. However, it has proven difficult to determine the firing temperatures of excavated moulds using existing analytical methods. This study establishes an innovative new method for using Fourier-transform infrared spectroscopy (FTIR) to estimate the firing temperature of clay-containing remains. The method is based on the finding that the infrared absorptivity of fired clay minerals, measured at the Si-O-Si stretching resonance band, is negatively correlated with firing temperature. Moulds and mould cores dating to the Early Shang period (sixteenth to fourteenth century BCE) are found to have been fired at extremely low temperatures-as low as 200-300 °C in many instances. These results provide critical new data for understanding the metallurgical technology of ancient China. The production of bronze vessels was the most prominent handicraft industry in Bronze Age China (c. twentieth to fifth century BCE) and was deeply embedded in the ritual and political systems of the Shang and Zhou dynasties. This essential industry has received abundant scholarly attention, including ongoing debates over the location of metal sources 1,2 , distribution networks 3 and casting techniques 4. Researchers have also increasingly focused on the tools used in the bronze production process and, in particular, on the manufacture of the high-performance ceramic moulds that made possible the complex casting methods used in ancient China 5,6. Understanding this mould-making technology is an essential component of the broader effort to understand diachronic change and regional variation in China's metallurgical industries during the Bronze Age. The firing temperature of moulds deserves particular attention, as it is a key technical factor in mould making, capable of significantly influencing the performance of ceramic moulds and mould cores during the bronze-casting process. However, using laboratory analyses to estimate the firing temperatures of excavated moulds and cores has been proved challenging. Initial attempts, based on measurement of moulds' thermal expansion behavior, found that moulds were fired at 900-1050 °C 7 , with some scholars additionally claiming that moulds' firing temperatures were deliberately kept between the decomposition temperature of calcite (850-900 °C) and the sintering temperature of typical clays (950-1000 °C) 8,9. However, research has shown that the thermal expansion method used in these initial analyses may significantly overestimate the firing temperatures of low-fired ceramics-i.e., of ceramics fired below the sintering temperature of clay 10. Recent investigations, using analytical methods better suited to low-fired ceramics, have found that moulds may have been fired at temperatures much lower than initially believed. Using a modified thermal expansion method, moulds and cores from the Western Zhou site of Zhouyuan (eleventh to eighth century BCE) and the Late Shang site of Xiaomintun (thirteenth to eleventh century BCE) were found to have been fired at 550-650 °C or lower 11,12. Additional mould and core samples from Xiaomintun, analyzed using thermoluminescence, were found to have been fired at 600-700 °C 13. Eastern Zhou-period moulds from Xinzheng (eighth-third century BCE) were determined to have been fired below 800 °C, due to the low degree of clay sintering observed by SEM imaging 5. Finally, a large study of 72 moulds from Zhouyuan used Fourier-transform infrared spectroscopy (FTIR) to determine that almost all of the moulds had been fired OPEN
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Journal of Archaeological Science, 2013
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Papers by Siran Liu
Journal of Archaeological Science
Abstract Micro-slag artefacts from ancient bronze casting workshops were largely ignored in previ... more Abstract Micro-slag artefacts from ancient bronze casting workshops were largely ignored in previous research despite their rich information potential. Current research demonstrates they could significantly enhance our understanding about past metallurgical activities but their identification requires careful in-situ analysis and a well-designed sampling strategy. Here we present an innovative methodology combining in-situ geochemical survey, wet-sieving of soil samples and detailed microscopic study, employed to investigate an important Middle-Shang site, Taijiasi, in the Huaihe River valley. The micro-slags from this site revealed that in addition to bronze alloying and casting, raw copper refining was also practiced. Material evidence for the refining process was not immediately visible in the archaeological excavation since most slag was mechanically crushed to retrieve any copper trapped in them, leaving only micro-slag fragments typically smaller than 3000 μm (3 mm). The fact that most micro-slag was recovered from one sector (H234) of a small building (F16) located on the same platform as the elites’ long houses suggests that mechanical processing of refining slag was conducted in a confined area and closely supervised. It might reflect people of this site valuing copper as a highly precious material and making all effort to recover copper otherwise lost in slag. This find will potentially shed new light on a range of important issues of Shang archaeology, including the regional variation of Shang metallurgical styles and the provenance of copper in the Shang period. This research also encourages researchers to look into archaeological soil samples with abnormally high copper content and understand the particles in them causing these high readings.
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Chinese Annals of History of Science and Technology, 2021
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Scientific Reports, 2021
Intricate ceramic bronze-casting moulds are among the most significant archaeological remains fou... more Intricate ceramic bronze-casting moulds are among the most significant archaeological remains found at Bronze Age metallurgical workshops in China. Firing temperature was presumably one of the most important technical factors in mould making. However, it has proven difficult to determine the firing temperatures of excavated moulds using existing analytical methods. This study establishes an innovative new method for using Fourier-transform infrared spectroscopy (FTIR) to estimate the firing temperature of clay-containing remains. The method is based on the finding that the infrared absorptivity of fired clay minerals, measured at the Si–O–Si stretching resonance band, is negatively correlated with firing temperature. Moulds and mould cores dating to the Early Shang period (sixteenth to fourteenth century BCE) are found to have been fired at extremely low temperatures—as low as 200–300 °C in many instances. These results provide critical new data for understanding the metallurgical t...
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Archaeometry, 2018
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Journal of Archaeological Science, 2019
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Archaeometry, 2018
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Journal of Archaeological Science, 2015
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Journal of Archaeological Science, 2015
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Journal of Cultural Heritage
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Papers on copper and its alloys by Siran Liu
Lead/silver smelting by Siran Liu
Technical ceramic by Siran Liu
Papers by Siran Liu