50 shades of...Blue!

More than grey and black, it is perhaps blue that evokes the idea of many chromatic shades. The history of techniques is full of receipts to prepare blue pigments and colorants and the culture of every country is rich of proofs of the use of mineral, organic and synthetic raw materials. Very often, the names of blue (word of Germanic origin) themselves are strictly connected to the materials from which they come from. 

Any examples?

Ultramarine blue: blue coming from the other part of the sea, that is from Afghanistan, the rock lapis lazuli, made basically of lazurite, a silicate of the sodalite group whose colour is due to the presence of sulphur in a particular oxidation state and position in the lattice; the Italian word azzurro, or the Spanish azul: name of Arabic origin, the same of the mineral azurite, a basic copper carbonate like the green mineral malachite, and not to be confused with lazurite; cobalt blue: from the wicked kobalt, goblins of the mines; indigo: from the plant, growing in India, Indigofera Tinctoria from which the blue colorant indigotina can be extracted; Prussian blue: a pigment synthetized by chance by a merchant of red colorants in Berlin in the 18^th century.

Less known, Egyptian blue: pigment made of a calcium copper silicate which could already be synthesized by the Egyptians; Maya Blue: used by this population and made of a mixture of clays and organic colorants; tekhelet: a substance of animal origin quoted in the Bible.

Why is this colour so important, and why in an archaeometry blog? Because it is sometimes essential to answer to some of the questions of this discipline: Where? When? How? More often than red, brown and green, it is the kind of blue used, I think, to make a difference, giving an answer to these problems.

Up to now, it allowed us to travel around the world along millennia, naming, of course, less than 50 shades of blue; nevertheless, if you are curious now, you are invited to go ahead, and you will discover that the history of this colour is much more than a simple novel.

To learn more:

* M Pastoureau, Bleu. Histoire d'une couleur, 2000. Essay
* Ph Ball, Bright Earth: Art and Invention of Color, 2003. Essay
* B Sterman, The rarest blue: the remarkable story of an ancient color lost to history and rediscovered, 2012. Essay about Tekhelet
* C Moore, Sacré Bleu, 2012. Novel

To learn more “Archaeometrically speaking”

* M Bacci, C Cucci, E Del Federico, A Ienco, A Jerschow, J M Newmand, M Picollo, An integrated spectroscopic approach for the identification of what distinguishes Afghan lapis lazuli from others, Vibrational Spectroscopy 49 (2009) 80–83.
* Ph Colomban, Lapis lazuli as unexpected blue pigment in Iranian Lajvardina ceramics, Journal of Raman Spectroscopy 34 (2003), 6, 420-423.

* B Hubbard, W Kuang, A Moser, G A Facey and C Detellier, Structural study of Maya Blue: textural, thermal and solid-state multinuclear magnetic resonance characterization of the palygorskite-indigo and sepiolite-indigo adducts, Clays and Clay Minerals 51 (2003), 3, 318-326.

* M Bicchieri, M Nardone, P A Russo, A Sodo, M Corsi, G Cristoforetti, V Palleschi, A Salvetti, E Tognoni, Characterization of azurite and lazurite based pigments by laser induced breakdown spectroscopy and micro-Raman spectroscopy, Spectrochimica Acta Part B: Atomic Spectroscopy 56 (2001), 6, 915–922.

* M Bouchard and A Gambardella, Raman microscopy study of synthetic cobalt blue spinels used in the field of art, Journal of Raman Spectroscopy 41 (2010) 1477–1485.

* S Pagès-Camagna, S Colinart, C Coupry, Fabrication processes of archaeological Egyptian blue and green pigments enlightened by Raman microscopy and scanning electron microscopy, Journal of Raman Spectroscopy 30 (1999), 4, 313-317.