Roman coloured glass in the Western provinces: The glass cakes and tesserae from West Clacton in England

Paynter, Sarah; Kearns, Thérèse; Cool, H. E. M.; Chenery, Simon

doi:10.1016/j.jas.2015.07.006

Cited by 32 publications

(44 citation statements)

References 29 publications

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“…Taking into account that Sb/Mn and Mn-glass groups were used for lower value items and were widely available around the Mediterranean and continental Europe, the present results confirm the preference for the most readily available and least costly glass types as base glass of tesserae, as already verified in Roman assemblage from UK [12]. All the red macro-group (in particular, the orange tesserae), except for tessera TN NS1, does not fit the Roman compositional groups, mainly due to higher alumina and lime and lower silica contents (Figure 2), as well as magnesia, potash, and phosphorus oxide.…”

Section: Glassy Matricessupporting

confidence: 86%

“…This was also confirmed by EPR analysis, which excluded the presence of copper and measured iron as Fe 2+ and Fe 3+ with a neat prevalence of Fe 3+ (Figure 11) in both PN VTR1 and PN VTR2. While the copper-based coloring technique employed in Trento is quite common, the two samples from Pordenone, both iron-colored, were produced using a technique that is rare in mosaic tesserae and was previously identified in one early Roman tessera (see sample 18 from West Clacton Reservoir [12,61]); such evidence reinforces the hypothesis of early Figure 10. Raman spectrum, in the region from 100 to 1000 cm −1 , of opacifier identified in tessera PN GSO2: note the presence of measured wavenumbers at 140, 330, 450, 510 typical of Pb-antimonate doped with tin (most intense signal in bold; reference spectra from [47,54,55]).…”

Section: Yellow and Green Tesseraesupporting

confidence: 58%

“…Interesting also to note that all the tesserae from Trento and Pordenone with Ca-antimonate, in which the in situ crystallization is hypothesized, show a glassy matrix comparable with Mn-glass type. The Mn-glass contains the highest proportion of calcium of Roman glass, making them intrinsically suitable for producing opaque glass, because calcium is conductive to the formation of the calcium antimonate opacifier [12]. In addition, the prevalence of CaSb 2 O 6 in Trento and Pordenone tesserae may be also facilitated by the low lead content of glassy matrix (Table 2), because this element could stimulate the crystallization of Ca 2 Sb 2 O 7 , as already observed in previous studies on Roman and modern opaque glass with high lead contents (from 2 to 25 wt % as PbO) [19].…”

Section: Turquoise Blue and White Tesseraementioning

confidence: 99%

“…This color, also named "peacock green" [61], is relatively rare in ancient glassmaking and is characteristic of the early Roman production of luxurious, deeply colored vessels; this kind of glass is usually characterized by the use of plant-ash based glass and copper oxide as a chromophore [12,34,61,62]. In the emerald green tesserae investigated here, the base glass employed is unequivocally natron-based, but, despite the apparent chromatic similarity among the three samples, a major compositional difference emerges (Table 2): in the case of TN VS1, copper is the colorant ion (1.84 wt % as CuO), while in the case of PN VTR1 and PN VTR2, the only colorant ion detected is iron (1.92 and 2.79 wt % as Fe 2 O 3 , respectively).…”

Section: Yellow and Green Tesseraementioning

confidence: 99%

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A Mosaic of Colors: Investigating Production Technologies of Roman Glass Tesserae from Northeastern Italy

Maltoni

Silvestri

2018

Minerals

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In the current study, a set of 60 glass tesserae from two disrupted Roman mosaics located in Pordenone and Trento (northeastern Italy) are analyzed, with the aim of investigating the coloring and opacification techniques, with a focus on the causes of specific textural features. All the available colors and textures were selected for archaeometric analyses, in order to guarantee the full characterization of both assemblages and comparisons between the two sites. The applied analytical protocol comprises micro-textural and preliminary chemical characterizations of the tesserae by means of OM and SEM-EDS, mineralogical analysis of the opacifiers by XRD and chemical analysis of the glassy matrices by EPMA; in addition, on specific tesserae, micro-Raman spectroscopy, FORS, and EPR were also performed to clarify the type of opacifer, coloring ion and oxidation state, respectively. Results show that both the base-glass and the coloring/opacification techniques identified are consistent with the presumed Roman dating of the mosaics. All the tesserae are natron-based and chemically comparable with major Roman compositional groups, except for red samples. Antimony-based opacifiers are identified in most of the blue, turquoise, white, yellow and green tesserae, and copper-based opacifiers in the red ones; cobalt and copper are the most frequent ionic colorants used to obtain various shades of blue, turquoise and green colors. Despite the general comparability of both assemblages with the published data on glass tesserae coeval in age, the present study shows differences in the technological solutions used for obtaining the same color, and less common coloring and opacification techniques in three samples from Pordenone. The banded textures of some tesserae were also carefully investigated, and multiple factors influencing the changes in color (different distribution or relative abundance of opacifiers, crystal size, micro-texture, chemical composition of glassy matrix) are identified.

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Section: Glassy Matricessupporting

confidence: 86%

Section: Yellow and Green Tesseraesupporting

confidence: 58%

Section: Turquoise Blue and White Tesseraementioning

confidence: 99%

Section: Yellow and Green Tesseraementioning

confidence: 99%

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A Mosaic of Colors: Investigating Production Technologies of Roman Glass Tesserae from Northeastern Italy

Maltoni

Silvestri

2018

Minerals

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“…Analytical conditions, sample preparation methods and precision/accuracy are given in Paynter et al 2015, checked against Corning glass standards. The tabulated results are averages of at least 3 analyses and normalised.…”

Section: Materials and Methodologymentioning

confidence: 99%

Glassmaking using natron from el-Barnugi (Egypt); Pliny and the Roman glass industry

Jackson

Paynter

Nenna

et al. 2016

Archaeol Anthropol Sci

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Pliny the Elder describes the discovery of a process for making natron glass, which was widely used for much of the first millennium BC and AD. His account of glassmaking with natron has since been corroborated by analyses of archaeological glass and the discovery of large-scale glass production sites where natron glass was made and then exported. Analyses of Egyptian natron have shown it to be a complex mixture of different sodium compounds, and previous experiments to make glass with Egyptian natron have been unsuccessful. Here, natron from el-Barnugi in the Egyptian Nile delta, a site which also probably supplied Roman glassmakers, is used to produce glass. The experiments show that highquality glass, free of unreacted batch or bubbles, could have been produced from natron in its unprocessed form in a single stage, that larger quantities of natron would be required than has previously been anticipated, that the presence of different sodium-containing compounds in the deposit aided melting, and that negligible waste is produced. The implications for the identification of glass production sites, for the organisation of trade and for the supply of natron within and outside Egypt are discussed in the light of Pliny's accounts.

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Innovation and tradition in the fourth century mosaic of the Casa delle Bestie Ferite in Aquileia, Italy: archaeometric characterisation of the glass tesserae

Maltoni¹,

Silvestri

2016

Archaeol Anthropol Sci

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The present paper focuses on the archaeometric characterisation of 38 glass tesserae of various colours from an in situ mosaic in Aquileia, Italy, dated to the second half of the fourth century AD. The examination of the textural, mineralogical and chemical features, conducted by means of a multi-methodological approach (optical microscopy (OM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), electron probe micro analysis (EPMA), X-ray diffraction (XRD) and Fibre Optic Reflectance Spectrophotometer (FORS)), has provided valuable insights into the changes in the production technology during the transition between the Roman and the Late Antique periods. The assemblage is heterogeneous, and each chromatic group is composed of tesserae produced with different base glasses and colouring/opacifying techniques, suggesting diverse supplies. A small group of tesserae shows strict links to the Roman tradition in terms of both base glass and colouring/ opacifying techniques and was probably obtained by re-using tesserae from older mosaics. Conversely, a larger group of tesserae shows textural and chemical evidence of recycling and indicates the prompt use of Bnew^ opacifying technologies (such as the use of tin compounds) or uncommon technological solutions (such as the use of quartz and bubbles as opacifiers or the addition of metallurgical slags in red tesserae), suggesting a specific production in the fourth century AD

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Roman coloured glass in the Western provinces: The glass cakes and tesserae from West Clacton in England

Cited by 32 publications

References 29 publications

A Mosaic of Colors: Investigating Production Technologies of Roman Glass Tesserae from Northeastern Italy

A Mosaic of Colors: Investigating Production Technologies of Roman Glass Tesserae from Northeastern Italy

Glassmaking using natron from el-Barnugi (Egypt); Pliny and the Roman glass industry

Innovation and tradition in the fourth century mosaic of the Casa delle Bestie Ferite in Aquileia, Italy: archaeometric characterisation of the glass tesserae

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