Investigation of Iron Age north-eastern Scottish glass beads using element analysis with LA-ICP-MS

Class 13 and 14 Iron Age Scottish glass beads are a group of highly decorated beads of British origin or design, dating indicatively to the 1st and 2nd century AD and typically found in Aberdeenshire and Moray district (Guido, 1978, 85–9). Their distinctive stylistic characteristics and geographical segregation renders them ideal for the investigation of whether the glasses employed in their manufacture were imported rather than produced locally, and for the assessment of the technology used in the production of the deep colours. Studies performed in the 1980s on different specimens pertaining to the same Classes (Henderson, 1982) showed compositional characteristics differing from Iron Age southern British beads, suggesting a different source of glass for their manufacture. Here, a set of 19 beads which was never investigated before was analysed for 32 major, minor and trace elements using Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The sample set shows good homogeneity in major and minor element composition, indicating the use of imported natron glass, with standardized composition typical of Roman glass of the period, also reflected in the recipes used for colouration. Evidence for the use of cullet and waste glass was found, which, along with the particularity of the design, suggests a local origin of the beads and possible production by native glassworkers.     

Analysis of Medieval and Post‐Medieval Glass Fragments from the Dubrovnik Region (Croatia)

Dubrovnik was an important trade city throughout the medieval and post‐medieval time period, maintaining its own glass production from the 14th to the 16th century. Unfortunately, Dubrovnik glass discoveries have not been well investigated up until now, except via archival data in large data analyses. In the following work, we will shed new light on the glass material found in this region, which has diverse origins, chronology, typology and style. Medieval and post‐medieval glass finds (10th/12th–18th centuries) discovered during archaeological excavations in Dubrovnik and the Dubrovnik region were analysed using particle‐induced X‐ray emission (PIXE) and particle‐induced gamma‐ray emission (PIGE), which revealed three main compositional groups: natron glass, plant‐ash glass and potash glass. This demonstrates the important commercial links present between Dubrovnik and other major glass‐making centres.     

Pre-Roman glass from Mozia (Sicily-Italy): the first archaeometrical data

This study present the results of an archaeometrical investigation performed on a series of opaque pre-Roman glass (vessels and ornaments) dated from the 6th to 4th century BC coming from Sicily. Sixteen core formed vessels, twelve beads, three pendants and one spindle-whorl recovered in the Phoenician-Punic sites of Mozia and Birgi were analysed thought a micro destructive approach. The complete chemical analyses and X-Ray diffraction analyses were performed on small fragments of glass. The aims of this work are: 1) to obtain a chemical characterization of these samples in order to understand the raw materials employed for their production; 2) to obtain information regarding the opacifying phases dispersed in the glass; 3) to make a comparison with the results recently obtained on coeval and similar finds recovered in other cultural context, in particular in Northern Italian Etruscan contexts in order to understand whether they could belong to the same Greek-Eastern production.     

Analysis of polychrome Iron Age glass vessels from Mediterranean I,II and III groups by LA-ICP-MS

In this work the analytical results obtained by ICP-MS with laser ablation solid sampling and SEM-EDS for some polychrome glass vessels from the Iron Age are presented and discussed. The samples, coming from Etruscan sites near Adria (Northern Italy), belong to the so-called Mediterranean Groups I, II and III and are dated from the 5th, 3rd and 2nd century B.C., respectively. To date, analytical data for only two sets of vessels of the Iron Age have been discussed in the literature. In spite of the low number of available samples, this is the first time that vessels of all three periods are analytically compared. Elemental concentration data show that the samples can be classified as low-magnesia-low potash (LMLK) soda-lime-silica glasses, with low phosphorus and titanium contents, in agreement with data for similar samples of the same age. Bivariate and multivariate analyses of the contents of many elements characterizing the siliceous sands showed three distinct sets corresponding to the three periods. Since the sets indicate different provenances of the sands it seems rational to assume that different glassmaking locations were involved. Chromophores and opacifiers of the blue bodies and the yellow, white and turquoise decorations of the vessels were analytically identified, while the nature of the corresponding ores was hypothesized.     

Chemical characterisation of glass mosaic tesserae from sixth-century Sagalassos (south-west Turkey): chronology and production techniques

Little is known about the origin, supply pattern and production technology of Byzantine glass mosaic tesserae. In this study, we have analysed forty-eight glass tesserae from Sagalassos (Asia Minor) of different colours and from two archaeological contexts that were stratigraphically dated to the sixth century CE. The main aim was to identify the raw materials, colourants and opacifiers as well as secondary working practices that are reflected in the composition (EPMA, LA-ICP-MS analyses) and the microstructure (XRD, SEM-BSE) of the tesserae. The set of samples retrieved from the Roman Baths complex at Sagalassos is compositionally very homogeneous, representing possibly a single commission, and can be tentatively dated to the late Roman period. In contrast, the assemblage associated with the construction of a Byzantine church around the turn of the sixth century CE is more diverse, suggesting that these tesserae were produced from more than one silica source. This highlights a diversification in the supply and manufacture of glass tesserae during the Byzantine period.     

The first archaeometric data on polychrome Iron Age glass from sites located in northern Italy

A large sample set of transparent and opaque glass artefacts recovered from Etruscan contexts in northern Italy (Bologna and Spina (FE) necropoleis) and dated to a period between the 6th and 4th century BC are analysed in this paper. Samples of highly decorated beads, spindle whorls and vessels of the ‘Mediterranean Group I’ (Alabastron, Oinochoes, Amphoriskos) were selected in order to determine whether these different glass artefacts were produced at the same manufacturing site. While the vessels almost certainly originate from Greece, the beads could derive from a more ancient local production ascertained at the site of Frattesina (Rovigo, Italy) and dated to the Bronze Age.     

A non-invasive study of Roman Age mosaic glass tesserae by means of Raman spectroscopy

Ancient mosaic tesserae are a range of materials of very varied and complex nature, including pottery, stone and glass. Raman spectroscopy is a powerful tool for the analysis of all these kinds of materials. In the particular case of glasses, this technique can be used both for a study of surface weathering and for the characterization of bulk structure, but it has not yet been extensively used for the characterization of mosaic glass tesserae. We carried out Raman analyses on a set of Roman and Late Antiquity period mosaic glass samples, which allowed a good characterization of both the glass matrix and the crystalline inclusions. All the samples show the typical Raman signatures of soda-lime-silicate glasses. Several crystalline phases were also identified, being relics of raw materials used during the glass manufacturing process, such as quartz and feldspars, or linked to the glass color/opacification, such as bindheimite and cuprite. The analyses also led to the identification in some blue, turquoise and green tesserae of calcium antimonate, whose Raman signature has only recently been recognized in the scientific literature on mosaic glasses. Some emphasis is given to the analysis of red lead-containing tesserae, colored with Cu⁺ ions or even Cu⁰ (or Au⁰) metal nanoparticles. Samples with peculiar compositions, as well as “modern” (and restoration) samples, could quite easily be distinguished from the ancient ones by their Raman spectra.     

Comments On ‘Technological Choices in Ceramic Production’, Archaeometry, 42(1), 1–76, 2000

Sillar, B., and Tite, M. S., 2000, The challenge of ‘technological choices for materials science approaches in archaeology, Archaeometry 42 , 2–20. Livingstone Smith, A., 2000, Processing clay for pottery in northern Cameroon: social and technical requirements, Archaeometry 42 , 21–42. Sillar, B., 2000, Dung by preference: the choice of fuel as an example of how Andean pottery production is embedded within wider technical, social, and economic practices, Archaeometry 42 , 43–60. Pool, C. A., 2000, Why a kiln? Firing technology in the Sierra de los Tuxtlas, Veracruz (Mexico), Archaeometry 42 , 61–76.     

Evidence for glass ‘recycling’ using Pb and Sr isotopic ratios and Sr-mixing lines: the case of early Byzantine Sagalassos

The secondary production (working) of glass from imperial to early Byzantine times has been proven at the ancient city of Sagalassos (SW Turkey) by the existence of glass chunks, fuel ash slag and kiln fragments related to glass processing. It had been previously suggested that local green glass might have been recycled from two other locally found glass types (blue glass vessels and chunks and HIMT glass chunks). This paper provides analytical evidence for the recycling of glass next to the use of imported raw glass. The heterogeneous lead isotopic composition of the green and HIMT vessel glass at Sagalassos, with as end members on the one hand the isotopic composition of local blue glass vessels and chunks and on the other hand that of the HIMT glass chunks, could indicate the production of ‘recycled’ glass, although heterogeneous raw materials could have been used. However, the use of Sr-mixing lines confirms local recycling. It is clear that the Sr in the green and HIMT vessels is a mixture of the Sr in the aforementioned end members. It cannot be proved whether the green ‘recycled’ glass was produced from a mixture of chunks alone, or from a mixture of cullet and chunks. Suggestions are made towards the possible origin of the raw materials for the blue and HIMT glass on the basis of Sr isotopic signatures and absolute Sr contents in the glass.     

From shell to glass: how beads reflect the changing cultural landscape of the seventeenth-century lower Potomac River valley

ABSTRACT

This article examines over 7,500 beads from eight Native archaeological sites located in the lower Potomac River valley in order to understand how changes in bead assemblages between AD 1300 and 1712 expressed an ever-evolving Chesapeake cultural landscape. This analysis demonstrates clear differences in the types and distributions of beads from mortuary and domestic/nonmortuary contexts. Ossuary contexts contained the highest frequency of beads with the number of beads increasing over time. Following the arrival of English settlers in the 1620s, glass beads begin to appear in ossuary contexts. Beads from domestic or nonmortuary contexts are fewer in number, and those present were manufactured using local materials, including bone and clay, as well as shell. However, after 1680, there is a shift from shell beads being predominate on Native sites, to sites containing exclusively glass beads, red and black glass beads in particular. Post-1680 sites appear to reflect Piscataway displacement and the disruption of indigenous trade routes, leading Natives to obtain beads from colonial vendors. The distribution of bead color, an important attribute for communicating Native states of being, also shifts after 1680, with assemblages once dominated by white shell beads now dominated by black and red glass beads.