The Color of Glass

Calas, Georges; Galoisy, Laurence; Cormier, Laurent

doi:10.1002/9781118801017.ch6.2

Cited by 4 publications

(4 citation statements)

References 17 publications

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“…In addition, the light and dark gre bands of the same sample have identical, though rather variable, composition in terms The effect of other transition elements on colors is difficult to evaluate with available EMPA data, as both chromium and nickel are below or very close to the detection limit. Manganese can reduce the green color arising from iron because it oxidizes Fe 2+ into Fe 3+ [29]. In Figure 9b, where Manganese content is plotted versus total iron, it is evident that no relation exists between the two elements in the obsidians of Sierra de las Navajas.…”

Section: Influence Of Chemical Composition On Obsidian Colormentioning

confidence: 97%

“…Other known coloring elements in glass are the other transition metals. Chromium-bearing artificial glasses have a characteristic green color, and adding nickel changes the color from green to yellow, brown, and purple, depending on its coordination and alkali content of the glass [29].…”

Section: Influence Of Chemical Composition On Obsidian Colormentioning

confidence: 99%

“…However, it has been demonstrated that the iron content alone does not completely explain the different colors displayed by obsidians, but it also depends on its redox state and on the arrangement of Fe atoms in the structure. In artificial colored glass, Fe 3+ is not an efficient coloring agent, whereas Fe 2+ , although usually less abundant, gives a characteristic green coloration [29]. The black or dark brown color shown by most obsidians is explained with mixed valence iron clusters representing the beginning of an ordered structure around Fe atoms, which can be considered as precursors of ultrananolites of magnetite [34].…”

Section: Influence Of Chemical Composition On Obsidian Colormentioning

confidence: 99%

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Influence of Chemical Composition and Microvesiculation on the Chromatic Features of the Obsidian of Sierra de las Navajas (Hidalgo, Mexico)

Donato

Barba

et al. 2022

Minerals

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The obsidian of Sierra de las Navajas is well known for its green color and gold hue. In order to relate these features with compositional and microtextural characteristics, we have carried out a microanalytical study by Wave Dispersion System associated to Electron Probe Micro-Analyzer, Scanning Electron Microscope observation, and X-rays micro-tomographic analyses of samples showing different colors (dark to light green, sometimes with bands of different color intensity) and hues (changing, uniform, no hue). In accordance with previous studies, the green color of the obsidian seems to be related to a high iron content, probably in its reduced state. However, no significant difference in composition occurs between dark and light green samples. The SEM observation and microtomographic study revealed the absence of microcrystals and the occurrence of vesicles of different size, shape, and orientation. Lighter green colors are shown by highly vesiculated surfaces, whereas non-vesiculated samples are darker. On the surfaces with a high concentration of coarse vesicles, a uniform golden hue is observed. Decreasing vesiculation gives a hue changing with the angle of incident light. However, when the vesicularity approaches zero, no hue is visible. The iso-orientation of vesicles along preferential directions and their distribution in bands determine the variation in color intensity and hue on differently oriented surfaces. Microvesiculation also influences other characteristics that were important features for the use of obsidian in the past, such as fracture, transparency, and roughness.

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Section: Influence Of Chemical Composition On Obsidian Colormentioning

confidence: 97%

Section: Influence Of Chemical Composition On Obsidian Colormentioning

confidence: 99%

Section: Influence Of Chemical Composition On Obsidian Colormentioning

confidence: 99%

See 1 more Smart Citation

Influence of Chemical Composition and Microvesiculation on the Chromatic Features of the Obsidian of Sierra de las Navajas (Hidalgo, Mexico)

Donato

Barba

et al. 2022

Minerals

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“…Certains éléments agissent aussi comme décolorant en modifiant l'état redox d'un autre élément multivalent. La couleur d'un verre contenant un élément de transition peut varier en fonction de la nature du verre (silicate, borate, phosphate) [39,40].…”

Section: La Transition Vitreuseunclassified

Le verre : un matériau d’hier, d’aujourd’hui et de demain

Cormier

2022

Matériaux & Techniques

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Les verres jouent un rôle fondamental dans notre quotidien tant au niveau économique, culturel, sociétal, énergétique que géologique. Les verres géologiques témoignent de l’activité ignée de la Terre et représentent une source importante d’outils et d’objets ornementaux du Paléolithique à nos jours. Désormais, les verres sont utilisés également pour fabriquer des matériaux techniques, tels que des récipients (plats, verres à boire, bocaux, carafes…), des écrans (télévision, ordinateur, smartphone…), des fibres aux multiples applications (renforcement, transport d’information, énergie, santé…), pour assurer le stockage de déchets domestiques ou nucléaires et, plus récemment, des biomatériaux (implants dentaires ou osseux…). Par conséquent, les verres à base de silice sont au cœur de l’histoire de la Terre et de l’humanité. La variation de composition des verres naturels et industriels est vaste mais sa structure repose généralement sur une ossature tétraédrique d’unités SiO4, l’épine dorsale de plus de 90% des verres qui nous entourent dans notre quotidien. Autour de cette ossature de silice, les autres éléments chimiques se répartissent en éléments modificateurs de réseau, compensateur de charge, colorants, volatiles, et l’ensemble constitue un matériau ou une substance chaque fois unique. Cet article propose de passer en revue les liens entre la structure, les propriétés et la composition chimique des verres, essentiellement à base de silicate.

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Alteration of medieval stained glass windows in atmospheric medium: review and simplified alteration model

et al. 2023

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Stained glass windows are a precious heritage to pass on to future generations. However, medieval stained glass windows are particularly altered due to their chemical composition and the effects of climatic (mainly water and temperature), environmental (pollution) and biological factors. In this review, we present the alteration patterns observed on ancient Si-K-Ca stained glass windows. To better understand their formation mechanisms and determine the alteration rates, different exposure campaigns to the current atmosphere in a position sheltered from rain or not and laboratory experiments in aqueous medium or in gaseous phase have been conducted. Either model glass or ancient stained glass windows were studied. Isotopic tracers (D, 18O, 29Si) have been used as they constitute a powerful tool to elucidate the involved processes and to measure their kinetics. Thanks to all of these data, an alteration scenario of medieval stained glass alteration is proposed. Besides, the extrapolation of kinetic data based on several hypotheses over seven centuries gives very consistent results compared to the ancient stained glass samples.

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The Color of Glass

Cited by 4 publications

References 17 publications

Influence of Chemical Composition and Microvesiculation on the Chromatic Features of the Obsidian of Sierra de las Navajas (Hidalgo, Mexico)

Influence of Chemical Composition and Microvesiculation on the Chromatic Features of the Obsidian of Sierra de las Navajas (Hidalgo, Mexico)

Le verre : un matériau d’hier, d’aujourd’hui et de demain

Alteration of medieval stained glass windows in atmospheric medium: review and simplified alteration model

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