Analytical characterization of glass tesserae from mosaics of early Christian basilicas in Albania

Vataj, Esmeralda; Hobdari, Elio; Röhrs, Stefan; Vandenabele, Peter; Civici, Nikolla

doi:10.1007/s00339-016-0661-z

Cited by 11 publications

(6 citation statements)

References 22 publications

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“…However, colour measurements have shown that such intermediate colours were used for glass mosaic tesserae excavated from sites of Early Christian basilicas in Albania (Vataj et al . ).…”

Section: Discussion Of the Analytical Resultsmentioning

confidence: 97%

Studying the process of enamel powder preparation for émail champlevé by colour measurements and μ‐X‐ray mappings

Röhrs

Lambacher²,

Tagle

2018

Archaeometry

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Colour measurements and non-destructive μ-X-ray mappings have been used for the first time in a comprehensive study of medieval émail champlevé works from different production areas in France and Germany. This approach has given a new insight into the enamel powder preparation process of the glass material used for enamelling. Colour measurements demonstrated that all production centres used glass of very similar hues, but with large differences in colour saturation. The μ-X-ray mapping results of blue enamels are described by a semi-qualitative approach. Significant variations in oxide contents of lead, cobalt, manganese and antimony oxides were found. The variations suggest that more than one glass material was used to prepare the powder for enamelling. The variations in antimony and cobalt show that glass had different degrees of opacity and colour depth. The manganese and lead contents, which do not correlate with the cobalt or antimony contents, indicate that probably glass of different base compositions was used to prepare the enamel powder for one champlevé field.

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“…However, colour measurements have shown that such intermediate colours were used for glass mosaic tesserae excavated from sites of Early Christian basilicas in Albania (Vataj et al . ).…”

Section: Discussion Of the Analytical Resultsmentioning

confidence: 97%

Studying the process of enamel powder preparation for émail champlevé by colour measurements and μ‐X‐ray mappings

Röhrs

Lambacher²,

Tagle

2018

Archaeometry

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“…Local micro-EDXRF confirmed this source of discrepancy and allowed us to perform the measurements on the areas with more vivid colors to track correlations between color intensity and trace elements. Some crystalline phases can be relevant coloring agents but the color in glasses is often caused by the addition of certain minor elements, which in their ionic form can integrate into the glass matrix [51] and these are often transition metals. Bulk compositions of the bluish tesserae (#7 and #8) are similar and, in agreement with their identified microcrystals, both tesserae show a significantly higher amount of Sb as compared with the greenish tessera (#12).…”

Section: Edxrf Measurementsmentioning

confidence: 99%

“…The deep blue color of tesserae, such as tessera #8, is surely induced by the presence of very low amounts of cobalt. The coloring power of this metal is far greater than that of other transition metals and a few hundred ppm are enough to produce the effect [51,82]; 305 ppm were found within tessera #8. Cobalt is also present in tessera #12 (115 ppm) but the most abundant coloring agent within the sage green tessera is cubic PbSnO 3 , this is an opacifier and yellow pigment known as lead-tin yellow II or anima (formally Pb(Sn,Si)O 3 ) [83].…”

Section: Colorantsmentioning

confidence: 99%

The Colors of the Circus Mosaic from Barcino (Roman Barcelona): Characterization, Provenance, and Technology Issues

et al. 2021

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Archaeometric studies on mosaics often concentrate only on glass tesserae, while comprehensive studies including both stone and glass tesserae are scarce; however, both types of tesserae can sometimes bring relevant data to elaborate archaeological knowledge on a studied mosaic. In this paper, a representative set of tesserae from a large polychrome Roman mosaic retrieved in Barcelona (NE Spain) is investigated using various methods. Most of the techniques were directly applied on samples prepared as petrographic thin sections (including polarized-light, cathodoluminescence and electron microscopies, and synchrotron through-the-substrate μX-ray diffraction). The results indicate that, from the ten sampled stone tesserae, there are (i) seven limestones, one of them identified as Alveolina limestone (early Eocene) from the southern Pyrenees (ii) two sandstones from Barcelona’s Montjuïc hill (Miocene) and, (iii) a Carrara white marble from the Apuan Alps (Italy). The profuse presence of tesserae of both local and imported materials with well-known uses in architecture, epigraphy, and sculpture could imply that tesserae were a by-product of their main use. Two different production technologies were identified for the three sampled glass tesserae. The concurrent use of antimony- and tin-based opacifiers is in agreement with the accepted archaeological chronology of the mosaic (4th century AD).

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“…Due to the typical light strong absorption of copper containing glasses, no other Raman signals were detected for this sample [80]. In addition, since it is known that the combination of PbO and SnO 2 at temperatures above 600 • C, with a Pb/Sn ratio around 3.5%, forms Pb 2 SnO 4 [106], and considering that the 15117RV sample displayed a much higher Pb/Sn ratio without any compositional difference between the surface and inner parts, the surface golden leaf could have been the result of Pb 2 SnO 4 formation, which is yellow and also featured by Raman signatures close to anatase [107,108].…”

Section: Red Opaque Glass Tesseramentioning

confidence: 99%

Non-Invasive Approach to Investigate the Mineralogy and Production Technology of the Mosaic Tesserae from the Roman Domus of Villa San Pancrazio (Taormina, Italy)

et al. 2021

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The archaeological excavations at Villa San Pancrazio (Taormina, Italy) are bringing to light a vast Roman-Imperial residential quarter featuring luxurious dwellings decorated with wall paintings and mosaic floors, pointing it out as one of the most significant archaeological sites of the city. The polychrome and black and white mosaics recovered date back to the middle Imperial period, during the 2nd century AD. This work deals with the first archaeometric investigations of the materials employed for the tesserae production with the aim of elucidating the mineralogical composition and obtaining analytical evidence that can contribute to extracting information related to their production technology. For that purpose, a non-invasive methodology, based on micro energy dispersive X-ray fluorescence (μ-EDXRF) spectrometry and Raman spectroscopy, was used to characterize a wide selection of stone, ceramic and glass tesserae. Chemometric tools were exploited to manage the large set of elemental data collected on black and white lithic samples, providing essential clues for the subsequent investigations. The results evidenced the employment of natural lithotypes (calcareous sedimentary, dolomitic and volcanic) local and imported, and also artificial materials, such as ceramic made firing magnesium-rich clays, soda-lime-silica glasses made with different opacifying and coloring agents (such as calcium antimoniate, cobalt and copper).

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Analytical characterization of glass tesserae from mosaics of early Christian basilicas in Albania

Cited by 11 publications

References 22 publications

Studying the process of enamel powder preparation for émail champlevé by colour measurements and μ‐X‐ray mappings

Studying the process of enamel powder preparation for émail champlevé by colour measurements and μ‐X‐ray mappings

The Colors of the Circus Mosaic from Barcino (Roman Barcelona): Characterization, Provenance, and Technology Issues

Non-Invasive Approach to Investigate the Mineralogy and Production Technology of the Mosaic Tesserae from the Roman Domus of Villa San Pancrazio (Taormina, Italy)

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