Editing Ultramarine (section)

=== Natural production ===
[[Lapis lazuli]] stone was historically mined near [[Sar-i Sang|Sar-i-Sang]] in modern-day Afghanistan and traded to Mesopotamia and ancient Egypt as early as the third millennium BCE.<ref>{{Cite book |last=Naweed |first=Hamid |url=https://books.google.com/books?id=VXFXSpIY7pcC&vq |title=Art Through the Ages in Afghanistan |date=28 Feb 2013 |publisher=Author House |isbn=9781481742757 |pages=45-46}}</ref>  

A method to produce ultramarine from lapis lazuli was introduced by the 5th century for use in Buddhist cave temples.<ref>{{Cite web |date=2017-11-20 |title=Afghanistan’s Beautiful Link to Da Vinci’s $450 Million ‘Salvator Mundi’ |url=https://www.huffpost.com/entry/afghanistans-beautiful-link-to-da-vincis-450-million_b_5a132ac0e4b010527d677f42 |access-date=2025-02-02 |website=HuffPost |language=en}}</ref> The method was described by [[Cennino Cennini]] in the 15th century. This process consisted of grinding the lapis lazuli mineral, mixing the ground material with melted [[wax]], [[resin]]s, and [[oil]]s, wrapping the resulting mass in a cloth, and then kneading it in a dilute lye solution, a [[potassium carbonate]] solution prepared by combining [[wood ash]] with water. The blue lazurite particles collect at the bottom of the pot, while the colorless crystalline material and other impurities remain at the top. This process was performed at least three times, with each successive extraction generating a lower quality material. The final extraction, consisting largely of colorless material as well as a few blue particles, brings forth ultramarine ash which is prized as a [[Glaze (painting technique)|glaze]] for its pale blue transparency.<ref>Lara Broecke, ''Cennino Cennini's ''Il Libro dell'Arte'': a New English Translation and Commentary with Italian Transcription'', Archetype 2015, pp. 89–90.</ref> This extensive process was specific to ultramarine because the mineral from which it is derived has a combination of both blue and colorless pigments. If an artist were to simply grind and wash lapis lazuli, the resulting powder would be a greyish-blue color that lacks purity and depth of color since lapis lazuli contains a high proportion of colorless material.<ref>{{Cite journal |last=Plesters |first=Joyce |date=1966 |title=Ultramarine Blue, Natural and Artificial |url=https://www.jstor.org/stable/1505446 |journal=Studies in Conservation |volume=11 |issue=2 |pages=62–91 |doi=10.2307/1505446 |jstor=1505446 |issn=0039-3630}}</ref>

Although the lapis lazuli stone itself is relatively inexpensive, the lengthy process of pulverizing, sifting, and washing to produce ultramarine makes the natural pigment quite valuable and roughly ten times more expensive than the stone it comes from. The high cost of the imported raw material and the long laborious process of extraction combined has been said to make high-quality ultramarine as expensive as [[gold]].<ref name="Ashok-39" /><ref name="Plesters-1966-64" />