Aspects of the Production of Cobalt‐blue Glass in Egypt

Cobalt‐blue glass of the Near and Middle Eastern Late Bronze Age has long been recognized as compositionally distinct from other contemporary glasses (Sayre 1967; Lilyquist et al. 1993). It has been suggested recently by Shortland and Tite (2000) that this chemical distinction reflects the use of Egyptian raw materials for making these glasses, different from those used to make glass in Mesopotamia, or its manufacture by Mesopotamian workmen, possibly in Egypt. This assumed that cobalt‐bearing alum from the Western Oases and mineral natron from the Wadi Natrun were used for the cobalt‐blue glass, while the other, probably Mesopotamian, glasses were made using plant ash as the main alkali source. This note discusses some technical aspects of the possible ways in which the cobalt could have been added to the glass, and how this relates to the likely raw glass used in its making. Combining earlier suggestions by Noll (1981) and Brill in Lilyquist et al. (1993), an alternative explanation of the chemical characteristics is suggested, maintaining that all the glasses under discussion were made using plant ash. Differences in alkali concentrations probably reflect different soil and plant chemistries, and the colorant was probably added to the glass after being precipitated from the alum as a complex cobalt aluminium hydroxide.     

Production Technology for Copper‐ and Cobalt‐Blue Vitreous Materials from the New Kingdom Site of Amarna—A Reappraisal*

Previously published data on the chemical compositions and microstructures of copper‐ and cobalt‐blue frit, glass and faience from the New Kingdom site of Amarna in Egypt ( Shortland 2000 ) are summarized. The data are then used to infer the raw materials and processes employed in the production of these vitreous materials. The results suggest that crushed quartz pebbles were the source of the quartz for all the materials, but that different sources of alkali, both natron and a range of plant ashes, were used in the production of each material. It seems probable that the cobalt‐rich alum colorant was pre‐treated before use by precipitating cobalt hydroxide from a solution of the alum by the addition of natron. It is further hypothesized that cobalt‐blue glass was produced by melting the cobalt‐blue frit together with additional plant ash and possibly quartz. Finally, it is suggested that, in glazing the cobalt‐blue Variant D faience first produced in the 18th Dynasty, the efflorescence or application method was selected according to object type.     

ANCIENT EXPLOITATION AND USE OF COBALT ALUMS FROM THE WESTERN OASES OF EGYPT*

Cobalt alums from the Western Oases of Egypt were used in the second millennium bc as a colorant to produce dark blue glasses and glazes. A collection of these alums was gathered together and analysed by a series of techniques to accurately characterize them. They were then used alongside artificial analogues in experimental work aiming to determine the process that was used to convert the raw alum into a suitable pigment that might be used in a glass. Finally, the broader picture of the use of these alums is considered together with the implications for the trade in these materials across the Near East and into Europe.     

Malkata and Lisht Glassmaking Technologies: Towards a Specific Link between Second Millennium BC

Elemental analyses have been conducted on 61 coloured opaque glasses from the Malkata and Lisht New Kingdom glass factories. The presence of tin in several of the blue glasses suggests that a bronze casting byproduct or corrosion product was the source of the copper colorant for these glasses. A positive correlation between the lead and antimony concentrations of the yellow and green opaque glasses, plus a consistent excess of lead oxide in these glasses, suggests the use of antimony‐rich cupellation litharge as the source for the Pb₂Sb₂O₇ , colorant in these glasses. The metallurgical byproducts used to colour the Malkata and Lisht glasses provide an explicit mechanism for Peltenburg's theory of interaction between second millennium BC glassmakers and contemporary metalworkers.     

ANALYSIS OF LATE BRONZE AGE GLASS AXES FROM NIPPUR—A NEW COBALT COLOURANT

A multidisciplinary study of a unique group of Late Bronze Age (LBA) ceremonial glass axe heads and other artefacts shows that these are the first significant group of glasses coloured with cobalt to be identified from the Near East. The axes were excavated from the site of Nippur, in present‐day Iraq. Several are incised with the names of three kings, which dates the material to the 14th–13th centuries bc . Analysis by laser ablation inductively coupled plasma mass spectrometry (LA–ICPMS) indicates that the glass had high magnesia (MgO) and potash (K₂O) associated with a plant‐ash flux and was coloured blue by copper or a combination of copper and cobalt. These glasses are similar, but not identical, in major element composition to blue‐coloured glasses manufactured in ancient Egypt and elsewhere in Mesopotamia in the same period. However, the Nippur cobalt‐ and copper‐coloured glasses exhibit significantly different trace elemental compositions compared to Egyptian glass coloured with cobalt, showing that the ancient Near Eastern glassmakers had clearly identified and utilized a distinctive cobalt ore source for the colouring of this glass. Since it was previously thought that the only cobalt ores exploited in the LBA were exclusively of Egyptian origin, this new finding provides new insights on the origins of glass and how it was traded during the Bronze Age period.     

RAW MATERIALS OF GLASS FROM AMARNA AND IMPLICATIONS FOR THE ORIGINS OF EGYPTIAN GLASS*

Analysis has been conducted on 19 blue glasses from Amarna in Middle Egypt dated to around 1350 BC. The results suggest that these glasses fall into two distinct types: cobalt coloured glasses with a natron based alkali made from local Egyptian materials, and copper coloured glasses with a plant ash alkali, which follow a Mesopotamian tradition of glass making. It is suggested that at least some of this copper/plant ash glass is imported into Egypt during the Amarna period despite extensive local production of cobalt/natron glass. Existing analyses (Lilyquist and Brill 1995) of the earliest glass from the reign of Tuthmosis III (c. 1450 BC) suggest that during this period the same two types of glass are present. Local Egyptian cobalt and natron in these early glasses implies that, despite the lack of archaeological evidence for production sites, glass was produced from its raw materials in Egypt as early as the reign of Tuthmosis III.     

Change in chemical composition of early Islamic glass excavated in Raya,Sinai Peninsula,Egypt: on-site analyses using a portable X-ray fluorescence spectrometer

The Raya port (eighth to 12th centuries) on the Sinai Peninsula, Egypt, was one of the important port cities for the Red Sea trade. We performed on-site analyses of Islamic glass vessels (used in eighth to 11th centuries) mainly from this site in Egypt using a portable XRF spectrometer. The aim of this paper is to contribute to our understanding of the chemical compositions of early Islamic glass vessels by comparing their archaeological date and typology. In the early Islamic period, glass objects were mainly produced from natron as the soda source. Among the natron glass analyzed in this study, glass vessels with low titanium and iron and high strontium contents, which were probably produced in the Syria–Palestine region, were excavated in the eighth century layer. From the ninth century layer, a large number of samples with high levels of calcium, titanium and iron, probably produced in Egypt, were found. It should be noted that a large number of glass vessels with this chemical composition were found at the Raya site, because this type of glass was rarely reported from other Islamic sites. We finally concluded that this type of glass seems to be produced under a fixed recipe, although some samples contain a colorant or decolorized materials.     

Studies on the Ground Layer of Lacquerwares from Between the Mid‐Warring States Period and the Mid‐Western Han Dynasty Unearthed in the Changsha Region

The Changsha region was an important place in China during the heyday of lacquerwares, from the Warring States Period to the Western Han Dynasty (476 bc – ad 9), when lacquerwares were used with varied styles and beautiful ornamentations. However, the process used to make lacquerware was previously unknown. By analysing samples of fragments of lacquerware found in the Changsha region dating back to between the Mid‐Warring States Period and the Mid‐Western Han Dynasty (390–87 bc ), this paper demonstrates the varied constitution of the ground layer by analysing the features of the technique using non‐destructive methods. It also shows that the use of potassium alum, gypsum, carbon and brochantite as fillers in the ground layer can be dated back to the Mid‐Warring States Period. Furthermore, a comparison of techniques for ground layers from the Changsha region and other areas in China during this period is proposed on this basis.     

LEAD ISOTOPIC ANALYSIS OF EIGHTEENTH‐DYNASTY EGYPTIAN EYEPAINTS AND LEAD ANTIMONATE COLOURANTS*

New lead isotopic analyses are presented for lead antimonate coloured glass and faience from Amarna in Middle Egypt and dated to around 1350 BC. When compared to existing data, these suggest that Gebel Zeit on the Red Sea coast of Egypt may be the source for some of the lead antimonate colourants used in Egypt and possibly for the galena kohls of Eighteenth‐Dynasty date as well.     

繁昌汤家山西周墓的再认识

繁昌汤家山西周墓是一座高等级的吴国墓葬。通过对长江下游西周至春秋时期吴国墓葬的等级规模和出土青铜器的比较研究,汤家山西周墓与丹徒烟墩山、荞麦山西周墓和北山顶、青龙山春秋墓属同一等级的墓葬,皆为吴王之墓;根据汤家山西周墓主身份和墓地位置推测,《左传》记载的"鸠兹"应为西周晚期的吴国都城。     

The production technology of Egyptian blue and green frits from second millennium BC Egypt and Mesopotamia

The microstructures and chemical compositions of some 55 Egyptian blue and green frit samples from New Kingdom Egypt and 15th century BC Mesopotamia are determined using analytical scanning electron microscopy, the main focus being on frit cakes, powder residues, and frit vessel and bead fragments from one of the “factory areas” at Amarna in Middle Egypt. Replicate Egyptian blue frits produced in the laboratory are similarly investigated. Comparison of the microstructures of the ancient and replicate samples suggest that frit cakes are the primary product, and that these were ground to produce the powder, and then moulded to shape and refired to produce the vessels and beads. Egyptian blue and green frits are shown to be distinct pigments, the pigment produced depending on the relative proportions of copper oxide and lime in the mixtures. The bulk and glass phase compositions are used to try to infer the different sources of the quartz, lime, copper and alkali flux used in the production of frits from Egypt and Mesopotamia. An estimate is made of the scale of production of Egyptian blue frit in New Kingdom Egypt.     

Transitions in Islamic plant-ash glass vessels: on-site chemical analyses conducted at the Raya/al-Tur area on the Sinai Peninsula in Egypt

This study focuses on the chemical composition of Islamic plant-ash glass (dated from the 9th to 11th centuries) excavated from the Raya/al-Tur area on the South Sinai in Egypt. Plant-ash glass objects from the Raya site were classified into three compositional types based on on-site chemical analyses with a portable X-ray fluorescence spectrometer. Based on typological characteristics and chemical composition comparisons with contemporary glass objects from other Islamic sites, one hypothesis holds that plant-ash glass objects produced in the Syria–Palestine or Mesopotamian regions could have been imported to Raya during the 9th to 10th centuries. In particular, some colorless glass vessels with a high magnesium/calcium ratio were noted to exhibit post-Sassanian cut decorations. Conversely, most of the bluish-green plant-ash glass objects from the Monastery of Wadi al-Tur near the Raya site exhibited relatively high levels of aluminum, titanium, iron, and lead. These pieces were likely produced during the Fatimid period (late 10th to 12th centuries), and based on their elemental composition, possibly originated in Egypt. The present work provides a greater understanding of chronological changes in post-9th century Islamic plant-ash glasses and the development of social and commercial networks within the Middle Eastern area.     

明早期官窑青花瓷器所用钴料的产地特征和晕散成因分析

为揭示明早期官窑青花瓷器所用钴料的产地特征和"色散而不收"的原因,以明早期官窑青花瓷器和阿联酋采集的伊斯兰蓝彩器标本为研究对象,采用能量色散X射线荧光光谱仪(EDXRF)和激光诱导击穿光谱分析(LIBS)分析方法分别对青花或者蓝彩纹饰部位以及釉的常规元素组成含量和氧化硼含量进行测试分析。结果表明:1)景德镇明早期青花瓷器所用钴料与伊斯兰蓝彩器标本类似,均为含有硼元素的经过预熔处理的低锰型钴料。2)明早期官窑青花瓷器"色散而不收"的主要原因在于其采用了含有硼的高钠、高钙以及低铝、低硅的预熔处理过的钴玻璃料。研究结果从硼元素角度佐证了明早期官窑青花瓷器所用的进口钴料可能来自于伊斯兰地区,为今后青花钴料的产地研究提供了新的视角和数据。     

Evidence for the trade of Mesopotamian and Egyptian glass to Mycenaean Greece

The origins of raw glass used to fashion Mycenaean beads were explored using trace elements analyzed by laser ablation ICP-TOFMS. The use of this minimally destructive technique for the in-situ analysis of these beads was ideal given that the material is exceedingly rare and thus too sensitive to make use of traditional micro-sampling (e.g., by scalpel). A wide range of trace elements were measured to compare these Greek glasses to other Late Bronze Age glass coming from Egypt and Mesopotamia. Of the eleven beads analyzed, four blue glasses colored with cobalt and two blue/green glasses colored with copper have trace element compositions consistent with an Egyptian origin of manufacture. The other five of the glasses, all colored with copper, were found to conform to the composition of Mesopotamian glass. These data are the first to demonstrate direct and clear evidence for the trade of raw glass to the Mycenaean states.     

Lisht as a New Kingdom Glass‐Making Site with Its Own Chemical Signature

Lisht is one of a few New Kingdom sites with known glass‐working debris. Here, we present evidence for the primary production of glass at Lisht, including crucible fragments and semi‐finished glass. We also provide 12 new chemical analyses of glass from Lisht, including trace elements. We argue that the glass made at Lisht has a specific chemical signature within the broader range of Late Bronze Age glass compositions from Egypt, further underlining the former existence of primary glass production there and offering the possibility of identifying Lisht‐made glass elsewhere in Egypt and beyond.     

Islamic glass in the Christian Kingdom of Alwa: Chemistry of shards from Soba,Nubia, Sudan

Excavations at Soba, the capital of Alwa, between 2019 and 2022 yielded more than 30 glass fragments in addition to a glass cosmetic bottle. An analysis of 30 glass samples has identified glass belonging to a number of compositional groups. The majority of fragments were made of plant ash-soda glass produced in the Middle East (Iran, Iraq) between the 9th and 10th centuries, and in the Eastern Mediterranean (Levant and Egypt) between the mid-10th and mid-12th centuries. Seven fragments were made of mineral–soda-lime glass produced in 9th-century Egypt and three high-lead glasses find analogies in the 9th- to 11th-century glass. Archeological evidence, as well as textual sources, leave no doubt about Alwa’s intense transcultural connections. This article provides the first insight into the chemistry of glass shards from medieval Nubia, and the results of analysis contribute to evidence for long-distance contacts of Soba, the capital of one of the medieval kingdoms of Sahelian Africa.     

中国钴着色材料的分类和来源

中国历史上的钴显色材料有颜料、玻璃、陶瓷釉。花绀青、钴蓝属历史颜料;钴显色蓝色玻璃可能始于西汉;钴显色蓝色陶瓷釉始于战国陶胎釉珠,唐朝唐三彩陶瓷釉发展成多个品种。钴显色材料有国产钴土矿类和进口Smalt类。原料矿中带入的锰、铁、镍、砷、铋等杂质对色彩有一定影响。     

XRF analysis of glass beads from the Mycenaean palace of Nestor at Pylos,Peloponnesus, Greece: new insight into the LBA glass trade

In recent years there has been a growing interest in Mycenaean glass among archaeologists and scientists. Scholars have traditionally thought that all Mycenaean glass was imported either in finished form or as ingots and simply shaped or worked at the Mycenaean sites. Chemical studies of other Mycenaean glass (50 and 43) support the hypothesis that glass was imported into Mycenaean Greece, but there is also indication for glass production in mainland Greece at the palace of Thebes (Nikita and Henderson, 2006). There is no evidence for glass making or working at the Palace of Pylos, yet there is an abundance of glass beads there. The aim of this paper is to identify the technology and source for the glass of these beads and thus to ascertain how Pylos was connected to the broader Mycenaean and Mediterranean economies. The composition of the glasses was determined by means of portable XRF analysis and compared to that of other Late Bronze Age glasses from Egypt, Mesopotamia and mainland Greece. Four blue beads coloured with cobalt and one blue bead coloured with copper have Ti and Zr compositions consistent with an Egyptian origin of manufacture while five other beads show Ti and Zr concentrations consistent with a Mesopotamian origin (Shortland et al., 2007). Based on the dearth of Egyptian and Mesopotamian imports in Pylos, the presented data support the hypothesis that Pylos was receiving via internal Greek trade routes foreign-produced glass, which may have been worked abroad or in Greece.     

故宫宁寿宫装饰彩瓷嵌片釉彩料的分析研究

故宫宁寿宫花园延趣楼、萃赏楼内檐装修釉上彩瓷装饰嵌片,是研究乾隆时期釉上彩瓷的珍贵标本。本研究采用X射线荧光能谱仪、显微激光拉曼光谱仪和实体显微镜,对乾隆时期釉上彩瓷样品进行无损分析。结果表明,蓝色、胭脂红色釉彩的基底釉为铅钾玻璃,白色、黄色、黄绿色、绿色釉彩的基底釉为铅玻璃。白彩的乳浊剂和着色剂为砷酸铅;蓝彩的乳浊剂为砷酸铅,着色元素为Co;黄彩为铅锡黄Ⅱ型乳浊及着色;黄绿彩为铅锡黄Ⅱ型和Cu共同作用;胭脂红彩为Au着色;绿彩为Cu着色;黑彩需覆盖透明绿彩于珠明料上才能完全发色;橘红彩为赤铁矿着色和乳浊;棕彩则为赤铁矿和Mn、Co共同着色。本研究成果可为乾隆时期釉上彩瓷的原料与工艺研究提供基础数据。     

Teardrops at the Lake: Chemistry of New Kingdom to Makuria Glass Beads and Pendants Between the First and Second Nile Cataracts

International expeditions extensively excavated Lower Nubia (between the First and Second Nile Cataracts) before it was submerged under the waters of Lake Nasser and Lake Nubia. The expeditions concentrated on monumental architecture and cemeteries, including sites at Qustul and Serra East, where the New Kingdom, and Napatan, Meroitic, Nobadian, and Makurian-period elites and common people were buried, ca. 1400 BC–AD 1400. Although the finds abound in adornments, including bead imports from Egypt and South India/Sri Lanka, only a few traces of local glass bead-making have been recorded in Nubia so far. Based on results of laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis of 76 glass beads, pendants, and chunks from Qustul and Serra East contexts, dated between the New Kingdom and the Makuria Kingdom periods, this paper discusses the composition and provenance of two types of plant-ash soda-lime (v-Na-Ca) glass, two types of mineral soda-lime glass (m-Na-Ca), and two types of mineral-soda-high alumina (m-Na-Al) glass. It also presents the remains of a probable local glass bead-making workshop dated to the period of intensive long-distance bead trade in Northeast Africa, AD 400–600.