Quantification of slag heap volumes and masses through the use of induced polarization: application to the Castel-Minier site

When used for archaeological purposes, geophysical methods are often useful for the exploration, detection and mapping of archaeological remains. In the case of ancient metallurgical activities, slag accumulations form precious mineral records of these activities. Evaluating the volume of slag produced in such locations is an important issue, since it enables an estimate of the amount of metal produced in the smeltery. Unfortunately, slags themselves cannot be easily detected by DC electrical methods. Although they can be easily detected using magnetic techniques, these methods do not allow for an estimate of the quantity of slag, because magnetic fields do not conserve magnetic flux. In the present study we show that the Induced Polarization method (IP) is suited to the quantification of buried slags, provided the slag response has been suitably calibrated prior to the field measurements. The ability to quantify the quantity of slag is based on the quasi-linear relationship between the main IP parameter, i.e., the chargeability, and the slag concentration. This approach provides a new, non-invasive tool for the estimation of the volume of buried slag in palaeometallurgical sites.In this paper, an application of this technique for the site of Castel-Minier, Ariège, France, is presented.     

炉渣分析揭示古代炼铜技术

对古代炼铜工艺、熔炼过程及其炉渣进行了分类,建立了以铜和硫的赋存状态与相对含量（Cu／S）鉴别炉渣种类,进而结合其它遗迹遗物来揭示古代炼铜技术的研究方法。     

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.     

Copper production at Baratti (Populonia,southern Tuscany) in the early Etruscan period (9th–8th centuries BC)

Populonia is commonly regarded as one of the most important iron working centres in Europe in the 1st millennium BC. However, multiple layers of copper slags have been recently discovered at the bottom of the slag deposit occurring along the shoreline of the underlying Baratti Gulf. Copper slag layers have been radiocarbon dated to the 9th–8th centuries BC, i.e. to an early metallurgical stage predating the later large-scale iron production. The overall features of copper slags indicate a single-step smelting process of copper-rich ores containing variable amounts of Zn and Pb. Chemical and textural features of copper slags indicate an optimised, high-efficiency metallurgical process.     

山东莱芜嬴城遗址炼铜渣初步研究

为了解山东地区早期冶金技术的发展情况,采用扫描电子显微镜分析等方法,对莱芜赢城冶炼遗址出土的3件炉渣进行了检测。结果表明其中2件为红铜还原渣,1件为砷铜熔炼渣。由此推测该遗址铜的还原可能存在两种工序,并且掌握了利用含砷矿物"点炼"铜液得到砷铜的技术。遗址所利用的铜可能来自于北江水铜矿,砷可能来自于鲁中山区,炉渣所属的时代应与遗址出土的商周青铜器年代相近。     

Roman traces in Germania magna: New thermoluminescence and pIRIR290 data from a lime kiln at Bergisch Gladbach,Germany

The applicability of a post‐infrared infrared stimulated luminescence (pIRIR₂₉₀) protocol and two different thermoluminescence (TL) protocols—a single aliquot regeneration (SAR) and a multiple aliquot additive dose (MAAD)—was tested on six polymineral fine‐grain (4–11 μm) samples extracted from the wall remains of a Roman lime kiln and a Roman roof tile. These remains had been excavated close to Bergisch Gladbach, which was at that time part of Germania magna. For the pIRIR₂₉₀ measurements, no dependence of D_e on first‐stimulation temperature was detectable, and the standard first stimulation temperature at 50°C was adopted. Fading tests and dose‐recovery tests were made for all samples. Background subtracted glow curves were recorded up to 480°C for TL after a preheat of 220°C for 120 s. A‐values were determined for all TL and pIRIR measurements. The results for all three protocols were fairly consistent, and TL and pIRIR₂₉₀ protocols are shown to be suitable to estimate reliable equivalent doses for the fired kiln walls. The resulting ages are in agreement with the expected time range—Roman Iron Age—and with independent age control provided by radiocarbon ages of animal bones and charcoal from the firing chamber.     

Copper Mines,Chromite Copper Ores and Slags of the Ishkinino Bronze Age Archaeological Microregion,The Southern Urals

The study addresses copper mines structure and composition of copper ores and slags at the Ishkinino archaeological microregion, Orenburg Province. Both ores and slags contain chromites derived from the host ultrabasite rock. Chromites were subdivided into three categories in terms of Cr2O3 content: 45–50%, 50–55%, and 55–61%. The proportions are similar to those observed in chromites of the malachite ores of the Ishkinino cobalt-copper-pyrite deposit. The reguli found in the slag contain copper sul?des and iron phosphides with a high content of nickel. Our results evidence the exploitation of local copper mines in the Late Bronze Age. Finds of chromite ores and slag at the archaeological sites of the Southern Urals are listed, and goals for future research are outlined.     

The Origin and Archaeometallurgy of a Mixed Sulphide Ore for Copper Production on the Island of Kea,Aegean Sea,Greece

At the hill of Agios Symeon, on the island of Kea, Aegean Sea, Greece, ancient metallurgical slags with a high Pb–Zn–Cu content have been found. Thermodynamic simulations have been carried out, using the FactSage? thermodynamic database computing system, with a view to understanding the ancient metallurgical processes that produced the observed slag compositions and morphologies. The simulations demonstrate that the slag samples resulted from Cu‐making processes. It would thus appear that mixed ores were used, containing Cu₂S–FeS–PbS with significant amounts of sphalerite (ZnS) as impurity. The roasted ores were reduced at relatively high oxygen potentials at ～1125°C to form Cu containing low levels of Pb, Fe and Zn.     

MINERALOGY OF MEDIEVAL SLAGS FROM LEAD AND SILVER SMELTING (BOHUTÍN,PŘÍBRAM DISTRICT,CZECH REPUBLIC): TOWARDS ESTIMATION OF HISTORICAL SMELTING CONDITIONS*

Slags from the Pb/Ag medieval (14th century) smelting plant located at Bohutín, P?íbram district, Czech Republic, were studied from the mineralogical and geochemical points of view. Two types of slags were distinguished: (i) quenched slags formed mainly by Pb‐rich glass and unmelted residual grains of SiO₂ and feldspars, and (ii) crystallized slags mainly composed of Fe‐rich olivine (fayalite) and glass. The mean log viscosity value of the slags calculated for 1200°C was 2.119 Pa s. The morphology of olivine crystals was used to estimate the cooling rates of the melt, for some slags indicating rates > 1450°C/h. The projection of the bulk composition of slags onto the SiO₂–PbO–FeO ternary system was used for rough temperature estimates of slag formation, lying probably between 800 and 1200°C.     

Problems of TL dating of the Mesopleistocene loess deposits in the Podillya and Pokuttya regions (Ukraine)

In many papers different authors was described problem of systematic underestimation of TL ages for sediments older then 100 ka. We presented the results which probably are not significantly rejuvenated. This is another example of the TL dates made in Lublin laboratory which are likely in agreement with the stratigraphic interpretation. In 2002 Kusiak et al. published the TL ages ranging from 200 to 800 ka for the Zahvizdja loess profile in Ukraine. These first promising results of TL dating of so old deposits encouraged us to undertake further studies. In next years were discovered other Ukrainian loess profiles with the Middle and Lower Pleistocene deposits, among others in the Skala Podils’ka, Mamalyha and Vendychany sites. The thermoluminescence dating made for these profiles in the Lublin laboratory gave the next, after Zahvizdja, series of 15 TL ages ranging from 200 to 700 ka. This way we confirmed the possibility of TL dating of the deposits older than 400 ka BP.     

REGIONAL VARIATIONS IN BLOOMERY SMELTING SLAG OF THE IRON AGE AND ROMANO‐BRITISH PERIODS*

This study highlights regional variation in the composition of iron‐smelting slag produced in England prior to the medieval period and attempts to link slag composition to the type of ore smelted. For many sites, the slag compositions were consistent with the use of limonite ore, but there is evidence that siderite ore was smelted at sites in Sussex in the late Iron Age/Romano‐British periods. A compositional comparison of smelting slags and slag inclusions in Iron Age currency bars, using data from Hedges and Salter (1979 ), illustrates the potential of smelting slag compositional data in provenance studies of early iron objects.     

Mineralogical And Chemical Investigations Of Bloomery Slags From Prehistoric (8th Century Bc To 4th Century Ad) Iron Production Sites In Upper And Lower Lusatia,Germany

More than 400 fayalitic bloomery slags from prehistoric iron production sites in Upper and Lower Lusatia, eastern Germany, as well as bog iron ore samples and intermediary samples of the smelting process, were analysed by chemical and mineralogical techniques. While the precursor bog iron ores exploited in the two regions under investigation were very similar in composition, consisting of low‐manganese/low‐barium as well as high‐manganese/high‐barium types of ore, pronounced differences in slag composition were detected. Slags from 17 investigated sites in Upper Lusatia showed average P₂O₅ contents between 1 and 3 mass%, whereas slags from 15 investigated sites in Lower Lusatia were generally much richer in phosphorus, reaching values as high as 7 mass% P₂O₅. Since a reasonable correlation exists between calcium and phosphorus contents in the slags of the latter sites, it is conjectured that deliberate addition of CaO to the ore/charcoal charge of the bloomery furnace may have taken place in order to fix the phosphorus in the slags effectively. In many samples, this conjecture is being supported by the detection of a slag mineral Ca–Fe phosphate Ca_9?xFe_1+x(PO₄)₇ that presumably crystallized from a residual phosphorus‐rich melt and shows a cotectic relationship to both Ca‐rich fayalite and wustite, as well as to members of the solid solution series magnetite–hercynite.     

The technology of tin smelting in the Rooiberg Valley,Limpopo Province,South Africa,ca. 1650–1850 CE

A substantial indigenous tin-smelting industry arose in the Rooiberg valley of northern South Africa in the second millennium CE. This study concentrates upon tin-smelting slags and refractory ceramics from two archaeological sites that date between ca. 1650 CE and ca. 1850 CE. These were studied by optical and electron microscopy, wavelength-dispersive x-ray fluorescence (WD-XRF), inductively-coupled plasma mass spectrometry (ICP-MS), and electron microprobe (EMPA). The slags are predominantly glassy; high SnO and relatively low SiO₂ contents indicate that tin is a major glass-forming element. Comparison of slag chemistries with the mineralogy of ore deposits and host rocks shows that alluvial cassiterite was used at one of the sites, while cassiterite from hard-rock mining was smelted at the other site. Since few preindustrial tin slags have been studied, we compare our findings to other published examples, mostly from southwest England.     

Iron smelting and smithing in major urban centers in Israel during the Iron Age

By-products of iron production, mainly slag and bloom fragments, unearthed at three Iron Age urban centres in Israel (Hazor, Tel Beer sheba and Rehov), were analysed in order to better understand the organization of iron production during the Iron Age. The production remains studied are all dated not earlier than the Iron Age IIA, and thus shed light on a period of transition from bronze to iron production. Chemical composition and microstructural analyses enable us to determine that both the smelting of iron ores and the refining of the bloom took place within the urban centres of Hazor and Beer-Sheba. We show that slag cakes are the products of smelting, possibly carried out in pit-furnaces. Hammerscales, products of primary and secondary smithing, were attached to slags. From these observations we infer that all stages of iron production were practiced in these urban centres.     

X荧光成分分析实验对测量陶瓷器热释光年代的影响研究

为了考察对一件已经经过X荧光分析实验的陶瓷样品进行热释光年代测定时,年代结果是否会受到X荧光分析实验的影响及其影响程度,本工作选取了古代与现代的陶器、瓷器及三彩样品共26件,在常规、经过胎体成分分析、经过釉层成分分析三种实验条件下测量比较热释光年代的变化.研究发现,对不同时代不同类型的样品,X荧光成分分析实验对热释光测年的影响程度不同;对部分样品的测年结果无影响,对部分样品的年代有增大的影响,但增大的程度不会使热释光测年结果产生真假颠倒的结论.     

Thermoluminescent dating of the Late Bronze and Early Iron Age pottery on sites in Kłyżów and Jarosław (SE Poland)

The absolute chronology of Late Bronze and Early Iron Ages in Polish territories is a result of long-term and complex research. Here, we have investigated the absolute dating of two sites, namely K?y?ów, a cemetery of the Tarnobrzeg Lusatian culture, and Jaros?aw, a settlement spanning from the late phase of the former to Pomeranian culture, possibly with Jastorf elements. Having been spurred by promising results of thermoluminescence (TL) dating of medieval and Przeworsk materials, we have employed it in those situations, where no other chronometric methods seem to be efficient. TL dating has been combined with typological analysis of the dated pottery and, partially, with radiocarbon method. Albeit the produced TL dates do not represent the level of sought-for fine chronological resolution, they indicate the temporal trends and corroborate the typological research. Our study has shown the potential of TL dating for periods with plateaus on ¹⁴C calibration curve. We also have dealt with unexpected TL ages and suggested some solutions of the problem. Finally, we have demonstrated that the condition sine qua non for archaeological interpretation of TL dates is a thorough stylistic-chronological analysis of dated pottery and clear understanding of relations between chronometric dates and the archaeological event to be dated.     

First Finding of Early Medieval Iron Slags in Sardinia (Italy): A Geochemical–Mineralogical Approach to Insights into Ore Provenance and Work Activity

At Santa Filitica, a Roman settlement in north‐western Sardinia occupied until the ninth century ad , archaeological excavations have found the remnants of a furnace consisting of a semi‐circular base made of stony slabs and tiles bound with clay. The furnace is attached to a wall of Roman age. Layers of the sixth century ad , bearing several variously oxidized slags, were found close to the furnace. These findings first testify to an ironworks in Sardinia, within a well‐defined context. XRPD and SEM–EDS mineralogical and textural analyses suggest that the slags derive from a bloomery and smithing work that was the first evidence of this type documented in Sardinia during the Early Middle Ages. Chemical analyses (performed with ICP and INAA) of rare earth elements and trace elements in two slags and in two Sardinian iron deposits allow some conclusions to be drawn on the local provenance of the ore. Our comparison of the Sardinian findings and some slags representative of archaeological smelting sites at the front of Elba island—the largest and longest lived iron‐working sites in the Mediterranean—also improves the methodology with which iron slags derived from different ores are compared.     

Mineralogical and Chemical Characterization of Roman Slag from the Archaeological Site of Castra (Ajdovščina,Slovenia)

This study deals with the mineralogical and chemical characterization of archaeometallurgical material from the Roman archaeological site of Castra (Ajdov??ina, western Slovenia). Samples were initially analysed via optical microscopy and X‐ray powder diffraction, with the composition of individual phases then determined using scanning electron microscopy coupled with electron‐dispersive spectroscopy, and Raman microspectroscopy. Chemical investigation was carried out by using inductively coupled plasma atomic emission spectroscopy to measure the major element content. The results showed that the slag originated from iron smithing operations, with calcium‐rich olivines, as well as wuestite and leucite, the most abundant phases. The investigated slags were also found to be characterized by significantly high lime levels, which probably promoted the formation of the calcium‐rich olivines.     

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.     

Late Bronze Age Copper Smelting Slags from Luserna (Trentino,Italy): Interpretation of the Metallurgical Process

In the Late Bronze Age, the extractive metallurgy of copper in north‐eastern Italy achieved a peak of technological efficiency and mass production, as evidenced by the substantial number of metallurgical sites and the large volume of slags resulting from smelting activities. In order to define the technological features of the Late Bronze Age metallurgical process, more than 20 slags from the smelting site of Luserna (Trentino, Italy) were fully analysed by means of optical microscopy, X‐ray powder diffraction, X‐ray fluorescence spectrometry and scanning electron microscopy. Three different slag types were identified based on mineralogical and chemico‐physical parameters, each being interpreted as the product of distinct metallurgical steps. A Cu‐smelting model is proposed accordingly.