Chemistry:Green earth
| Green earth | |
|---|---|
 Green earth pigment | |
 Color coordinates | |
| Hex triplet | #DADD98 |
| Source | Derwent[1] |
| ISCC–NBS descriptor | Light yellow green |
Green earth, also known as terre verte and Verona green, is an inorganic pigment derived from the minerals celadonite and glauconite.[2][3][4] Its chemical formula is K[(Al,Fe3+
),(Fe2+
,Mg)](AlSi
3,Si
4)O
10(OH)
2.[5]
First used by the ancient Romans, green earth has been identified on wall paintings at Pompeii and Dura-Europos.[6][7] The Renaissance painter and writer Cennino Cennini claimed that “the ancients never gilded except with this green” being used as a bole, or undercoating. In the Middle Ages one of its best-known uses was in the underpainting of flesh tones.[5]
Green earths have been rather confusingly referred to as "verda terra" or "terra verde di Verona", which scholars have assumed incorrectly referred to Veronese green, which is actually an emerald green pigment much used in the 18th century.[8] SEM/EDAXS data have demonstrated that it is possible to discriminate between these two sources of celadonite in Roman wall paintings through the presence of trace elements.[9] Spectroscopically, therefore, the analytical challenge is to differentiate between the green earths celadonite and glauconite, and perhaps chlorite, and the copper-containing malachite and verdigris, with the added ability to recognize the presence of haematite, Egyptian blue, calcite, dolomite, and carbon which have been added to change the colour tones.
High quality deposits can be found in England, France, Cyprus, Germany and at Monte Baldo near Verona in Italy.[7] The color ranges from neutral yellow green to pale greenish gray to dark matte olive green.[5][4]
See also
References
- ↑ The color in the color box above matches the color called green earth in Derwent colored pencils.[citation needed]
- ↑ Green earth Colourlex. Retrieved August 29, 2016.
- ↑ Green earth. Pigments through the Ages. www.webexhibits.com. Retrieved August 29, 2016.
- ↑ 4.0 4.1 St. Clair, Kassia (2016). The Secret Lives of Colour. London: John Murray. pp. 224–226. ISBN 9781473630819. OCLC 936144129.
- ↑ 5.0 5.1 5.2 Common Medieval Pigments. d-scholarship.pitt.edu. Retrieved August 29, 2016.
- ↑ Varichon, Anne (2000). Couleurs – pigments et teintures dans les mains des peuples. Seuil. pp. 210–211. ISBN 978-2-02084697-4.
- ↑ 7.0 7.1 Terre Verte. https://www.library.cornell.edu/preservation/paper/4PigAtlasWestern1.pdf. Retrieved August 30, 2016.
- ↑ Susana E. Jorge-Villar; Howell G.M. Edwards (2021). "Green and blue pigments in Roman wall paintings: A challenge for Raman spectroscopy". Journal of Raman Spectroscopy 52 (12): 2190–2203. doi:10.1002/jrs.6118. Bibcode: 2021JRSp...52.2190J. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/jrs.6118?af=R. Retrieved 26 February 2022.
- ↑ H.G.M. Edwards (2015). Encyclopedia of Analytical Chemistry. doi:10.1002/9780470027318.a9527. https://doi.org/10.1002/9780470027318.a9527. Retrieved 26 February 2022.
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