New insight on the in situ crystallization of calcium antimonate opacified glass during the Roman period

Lahlil, Sophia; Biron, Isabelle; Cotte, Marine; Susini, J.

doi:10.1007/s00339-010-5650-z

Cited by 66 publications

(67 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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 Tesseraesupporting

confidence: 55%

“…For the other tesserae from Pordenone and Trento with Ca-antimonate, showing euhedral crystals finely dispersed in the glass matrix (TN TU1, TN AQ1, TN AQ2, PN BO1, PN AZ1, TN AZ1, TN AZ2, PN BIOP1, TN GR2, PN VCH1), the hypothesis of in situ crystallization is more reliable. In previous studies on Roman glass tesserae the in situ crystallization is the opacification process, preferentially identified for the production of Ca-antimonate [19], while the present results show that both methods are used, and no relationships between production method and color or site are noted.…”

Section: Turquoise Blue and White Tesseraecontrasting

confidence: 42%

“…In addition, an experimental study on syntheses of in situ Ca-antimonate opacified glass carried out at 1100 °C from periods ranging from 30 min to 13 days, highlights that CaSb2O6 is kinetically favored, whereas Ca2Sb2O7 is thermodynamically stable [19]. Therefore, the presence of both phases, with a prevalence of the hexagonal one, in samples TN AQ1, TN AQ2, PN VCH1, PN BO1 and TN GR2 suggests a firing time of 1-2 days and a temperature of approximately 1100 °C, while the presence of only the hexagonal phase in TN TU1, TN AZ1, TN AZ2, and PN BIOP1, indicates shorter firing times and higher temperatures (over 1100 °C).…”

Section: Turquoise Blue and White Tesseraementioning

confidence: 99%

See 2 more Smart Citations

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

Maltoni

Silvestri

2018

Minerals

View full text Add to dashboard Cite

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.

show abstract

Section: Turquoise Blue and White Tesseraesupporting

confidence: 55%

Section: Turquoise Blue and White Tesseraecontrasting

confidence: 42%

Section: Turquoise Blue and White Tesseraementioning

confidence: 99%

See 1 more Smart Citation

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

Maltoni

Silvestri

2018

Minerals

View full text Add to dashboard Cite

show abstract

“…3d). These properties are not compatible with in situ crystallization, where nucleation of the crystals occurs randomly or at preferen- tial nucleation sites in the vitreous matrix [24]. Indeed, in all the in situ opacified glasses synthesized, we observe mainly isolated crystals or crystals around bubbles, and sometimes aggregates resulting from poorly dissolved antimony (Fig.…”

Section: Resultsmentioning

confidence: 68%

“…5a) (Fig. 5b) [24]. Therefore, the oxidation state of antimony in the vitreous matrix appears to be an efficient criterion to distinguish the addition of calcium antimonate crystals into a glass from the in situ crystallization.…”

Section: Resultsmentioning

confidence: 92%

Synthesis of calcium antimonate nano-crystals by the 18th dynasty Egyptian glassmakers

et al. 2009

Self Cite

View full text Add to dashboard Cite

During the 18th Egyptian dynasty (1570-1292 B.C.), opaque white, blue and turquoise glasses were opacified by calcium antimonate crystals dispersed in a vitreous matrix. The technological processes as well as the antimony sources used to manufacture these crystals remain unknown. Our results shed a new light on glassmaking history: contrary to what was thought, we demonstrate that Egyptian glassmakers did not use in situ crystallization but first synthesized calcium antimonate opacifiers, which do not exist in nature, and then added them to a glass. Furthermore, using transmission electron microscopy (TEM) for the first time in the study of Egyptian opaque glasses, we show that these opacifiers were nano-crystals. Prior to this research, such a process for glassmaking has not been suggested for any kind of ancient opaque glass production. Studying various preparation methods for calcium antimonate, we propose that Egyptian craftsmen could have produced Ca 2 Sb 2 O 7 by using mixtures of Sb 2 O 3 or Sb 2 O 5 with calcium carbonates (atomic ratio Sb/Ca = 1) heat treated between 1000 and 1100°C. We developed an original strategy S. Lahlil ( ) · I. Biron · M. Cotte

show abstract

Colouring, Decolouring and Opacifying of Glass

Biron

Chopinet

2013

Modern Methods for Analysing Archaeological and Historical Glass

View full text Add to dashboard Cite

New insight on the in situ crystallization of calcium antimonate opacified glass during the Roman period

Cited by 66 publications

References 22 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

Synthesis of calcium antimonate nano-crystals by the 18th dynasty Egyptian glassmakers

Colouring, Decolouring and Opacifying of Glass

Contact Info

Product

Resources

About