Editing Azurite (section)

===Pigments===

Azurite is unstable in air, however it was used as a [[Azurite (pigment)|blue pigment]] in antiquity.<ref>Gettens, R.J. and Fitzhugh, E.W., Azurite and Blue Verditer, in Artists’ Pigments. A Handbook of Their History and Characteristics, Vol. 2: A. Roy (Ed.) Oxford University Press 1993, p. 23–24</ref> Azurite is naturally occurring in Sinai and the Eastern Desert of Egypt. It was reported by [[Flaxman Charles John Spurrell|F. C. J. Spurrell]] (1895) in the following examples; a shell used as a pallet in a [[Fourth Dynasty of Egypt|Fourth Dynasty]] (2613 to 2494 BCE) context in [[Meidum]], a cloth over the face of a [[Fifth Dynasty of Egypt|Fifth Dynasty]] (2494 to 2345 BCE) mummy also at [[Meidum]] and a number of [[Eighteenth Dynasty of Egypt|Eighteenth Dynasty]] (1543–1292 BCE) wall paintings.<ref>{{Cite book|title=Ancient Egyptian Materials and Technology|last1=Nicholson|first1=Paul|last2=Shaw|first2=Ian|publisher=Cambridge University Press|year=2000|isbn=978-0521452571}}</ref> Depending on the degree of fineness to which it was ground, and its basic content of copper carbonate, it gave a wide range of blues. It has been known as ''mountain blue'', ''Armenian stone'', and ''azurro della Magna'' (''blue from Germany'' in [[Italian language|Italian]]). When mixed with oil it turns slightly green. When mixed with [[egg yolk]] it turns green-grey. It is also known by the names ''[[Bice|blue bice]]'' and ''blue verditer'', though ''[[Copper(II) hydroxide|verditer]]'' usually refers to a pigment made by chemical process. Older examples of azurite pigment may show a more greenish tint due to weathering into malachite. Much azurite was mislabeled ''[[lapis lazuli]]'', a term applied to many blue pigments. As chemical analysis of paintings from the [[Middle Ages]] improves, azurite is being recognized as a major source of the blues used by medieval painters. Lapis lazuli (the pigment ultramarine) was chiefly supplied from Afghanistan during the Middle Ages, whereas azurite was a common mineral in Europe at the time. Sizable deposits were found near Lyons, France. It was mined since the 12th century in [[Saxony]], in the silver mines located there.<ref>Andersen, Frank J. ''Riches of the Earth''. W.H. Smith Publishers, New York, 1981, {{ISBN|0-8317-7739-7}}</ref>

Heating can be used to distinguish azurite from purified natural [[ultramarine]] blue, a more expensive but more stable blue pigment, as described by [[Cennino D'Andrea Cennini]]. Ultramarine withstands heat, whereas azurite converts to black copper oxide.<ref>{{cite journal |last1=Muller |first1=Norman E. |title=Three Methods of Modelling the Virgin's Mantle in Early Itallan Painting |journal=Journal of the American Institute for Conservation |date=January 1978 |volume=17 |issue=2 |pages=10–18 |doi=10.1179/019713678806029166}}</ref> However, gentle heating of azurite produces a deep blue pigment used in Japanese painting techniques.<ref>{{cite journal |last1=Nishio |first1=Yoshiyuki |title=Pigments Used in Japanese Paintings |journal=The Paper Conservator |date=January 1987 |volume=11 |issue=1 |pages=39–45 |doi=10.1080/03094227.1987.9638544}}</ref>

Azurite pigment can be synthesized by precipitating [[copper(II) hydroxide]] from a solution of [[copper(II) chloride]] with [[lime (material)|lime]] ([[calcium hydroxide]]) and treating the precipitate with a concentrated solution of [[potassium carbonate]] and lime. This pigment is likely to contain traces of basic copper(II) chlorides.<ref>{{cite journal |last1=Orna |first1=Mary Virginia |last2=Low |first2=Manfred J. D. |last3=Baer |first3=Norbert S. |title=Synthetic Blue Pigments: Ninth to Sixteenth Centuries. I. Literature |journal=Studies in Conservation |date=May 1980 |volume=25 |issue=2 |pages=53 |doi=10.2307/1505860|jstor=1505860 }}</ref>

<gallery mode="packed" heights="160px">
File:Azuritepigment.jpg|Ground azurite for use as a pigment
File:Lady with a Squirrel.jpg|The background of ''Lady with a Squirrel'' by [[Hans Holbein the Younger]] was painted with azurite
File:Madonna and Child Enthroned with Saints.jpg|The greenish tint of the Madonna's mantle in [[Raphael]]'s ''Madonna and Child Enthroned with Saints'' is due to azurite weathering to malachite
</gallery>