Editing Lapis lazuli (section)

==Science and uses==
===Composition===
The most important mineral component of lapis lazuli is [[lazurite]]<ref>{{Cite web|url=https://www.mindat.org/min-2330.html|title=Lapis lazuli: Mineral information, data and localities.|website=www.mindat.org|access-date=2020-02-13|archive-date=2020-01-29|archive-url=https://web.archive.org/web/20200129083053/https://www.mindat.org/min-2330.html|url-status=live}}</ref> (25% to 40%),{{citation needed|date=August 2024}} a blue [[feldspathoid]] [[silicate mineral]] of the sodalite family, with the formula Na<sub>7</sub>Ca(Al<sub>6</sub>Si<sub>6</sub>O<sub>24</sub>)(SO<sub>4</sub>)(S<sub>3</sub>) ·H<sub>2</sub>O .<ref>{{Cite web|url=https://www.mindat.org/min-2357.html|title=Lazurite: Mineral information, data and localities.|website=www.mindat.org|access-date=2020-02-13|archive-date=2020-04-03|archive-url=https://web.archive.org/web/20200403042835/https://www.mindat.org/min-2357.html|url-status=live}}</ref> Most lapis lazuli also contains [[calcite]] (white), and [[pyrite]] (metallic yellow). Some samples of lapis lazuli contain [[augite]], [[diopside]], [[enstatite]], [[mica]], [[hauynite]], [[hornblende]], [[nosean]], and sulfur-rich [[löllingite]] ''geyerite''.

Lapis lazuli usually occurs in crystalline [[marble]] as a result of [[contact metamorphism]].

===Color===

[[File:Lapis-Lazuli microscope x240.jpg|thumb|upright|Lapis lazuli seen through a microscope (x240 magnification)]]

The intense blue color is due to the presence of the [[trisulfur]] [[radical anion]] ({{chem|S|3|•−}}) in the crystal.<ref>{{cite journal | last1 = Boros | first1 = E. | last2 = Earle | first2 = M. J. | last3 = Gilea | first3 = M. A. | last4 = Metlen | first4 = A. | last5 = Mudring | first5 = A.-V. | last6 = Rieger | first6 = F. | last7 = Robertson | first7 = A. J. | last8 = Seddon | first8 = K. R. | last9 = Tomaszowska | first9 = A. A. | last10 = Trusov | first10 = L. | last11 = Vyle | first11 = J. S. | year = 2010 | title = On the dissolution of non-metallic solid elements (sulfur, selenium, tellurium and phosphorus) in ionic liquids | url = https://works.bepress.com/anja_mudring/33/download/ | journal = Chem. Comm. | volume = 46 | issue = 5 | pages = 716–718 | doi = 10.1039/b910469k | pmid = 20087497 | access-date = 2018-04-20 | archive-date = 2017-09-22 | archive-url = https://web.archive.org/web/20170922042128/https://works.bepress.com/anja_mudring/33/download/ | url-status = live | url-access = subscription }}</ref> The presence of disulfur ({{chem|S|2|•−}}) and tetrasulfur ({{chem|S|4|•−}}) radicals can shift the color towards yellow or red, respectively.<ref>{{Cite journal |last1=Ganio |first1=Monica |last2=Pouyet |first2=Emeline S. |last3=Webb |first3=Samuel M. |last4=Patterson |first4=Catherine M. Schmidt |last5=Walton |first5=Marc S. |date=2018-03-01 |title=From lapis lazuli to ultramarine blue: investigating Cennino Cennini's recipe using sulfur K-edge XANES |journal=Pure and Applied Chemistry |language=en |volume=90 |issue=3 |pages=463–475 |doi=10.1515/pac-2017-0502 |s2cid=102593589 |issn=1365-3075 |doi-access=free }}</ref> These radical anions substitute for the chloride anions within the [[sodalite]] structure.<ref>{{Cite journal |last1=Reinen |first1=Dirk |last2=Lindner |first2=Gottlieb-Georg |date=1999-01-01 |title=The nature of the chalcogen colour centres in ultramarine-type solids |url=https://pubs.rsc.org/en/content/articlelanding/1999/cs/a704920j |journal=Chemical Society Reviews |language=en |volume=28 |issue=2 |pages=75–84 |doi=10.1039/A704920J |issn=1460-4744 |access-date=2022-06-16 |archive-date=2022-06-16 |archive-url=https://web.archive.org/web/20220616174412/https://pubs.rsc.org/en/content/articlelanding/1999/CS/a704920j |url-status=live |url-access=subscription }}</ref> The {{chem|S|3|•−}} radical anion exhibits a visible absorption band in the range 595–620&nbsp;nm with high molar absorptivity, leading to its bright blue color.<ref>{{Cite journal |last1=Chivers |first1=Tristram |last2=Elder |first2=Philip J. W. |date=2013-06-21 |title=Ubiquitous trisulfur radical anion: fundamentals and applications in materials science, electrochemistry, analytical chemistry and geochemistry |url=https://pubs.rsc.org/en/content/articlelanding/2013/cs/c3cs60119f |journal=Chemical Society Reviews |language=en |volume=42 |issue=14 |pages=5996–6005 |doi=10.1039/C3CS60119F |pmid=23628896 |issn=1460-4744 |access-date=2022-06-16 |archive-date=2022-06-16 |archive-url=https://web.archive.org/web/20220616174349/https://pubs.rsc.org/en/content/articlelanding/2013/cs/c3cs60119f |url-status=live |url-access=subscription }}</ref>

===Sources===
Lapis lazuli is found in limestone in the [[Kokcha River]] valley of [[Badakhshan]] province in north-eastern Afghanistan, where the [[Sar-i Sang]] mine deposits have been worked for more than 6,000 years.<ref name="Oldershaw-2003">{{Harvcolnb|Oldershaw|2003}}</ref> Afghanistan was the source of lapis for the ancient Persian, Egyptian and Mesopotamian civilizations, as well as the later Greeks and Romans. Ancient Egyptians obtained the material through trade with Mesopotamians, as part of [[Egypt–Mesopotamia relations]] and from ancient [[Ethiopia]] . During the height of the [[Indus Valley civilisation]], approximately 2000 BC, the Harappan colony, now known as [[Shortugai]], was established near the lapis mines.<ref name=bc1995/>

In addition to the Afghan deposits, lapis is also extracted in the [[Andes]] (near [[Ovalle, Chile|Ovalle]], [[Chile]]); and to the west of [[Lake Baikal]] in Siberia, Russia, at the Tultui lazurite deposit. It is mined in smaller amounts in [[Angola]], Argentina, [[Burma]], [[Ethiopia]], Pakistan, Canada, Italy, India, and in the United States in [[California]] and [[Colorado]].<ref name="ICGA"/>

===Uses and substitutes===
Lapis takes an excellent polish and can be made into jewellery, carvings, boxes, [[mosaic]]s, ornaments, small statues, and vases. Interior items and finishing buildings can be also made with lapis. During the [[Renaissance]], lapis was ground and processed to make the [[pigment]] [[ultramarine]] for use in [[fresco]]es and [[oil painting]]. Its usage as a pigment in oil paint largely ended during the early 19th century, when a chemically identical synthetic variety became available.

Lapis lazuli is commercially synthesized or simulated by the Gillson process, which is used to make artificial [[ultramarine]] and [[Hydrate|hydrous]] [[zinc phosphate]]s.<ref>Read, Peter (2005). ''[https://books.google.com/books?id=t-OQO3Wk-JsC&pg=PA185 Gemmology] {{Webarchive|url=https://web.archive.org/web/20161124003535/https://books.google.com/books?id=t-OQO3Wk-JsC&pg=PA185 |date=2016-11-24 }}'', Elsevier, p. 185. {{ISBN|0-7506-6449-5}}.</ref> [[Spinel]] or [[sodalite]], or dyed [[jasper]] or [[howlite]], can be substituted for lapis.<ref>[http://www.gemstonebuzz.com/lapis-lazuli Lapis lazuli] {{Webarchive|url=https://web.archive.org/web/20191027192333/http://www.gemstonebuzz.com/lapis-lazuli |date=2019-10-27 }}, Gemstone Buzz.</ref>

<gallery>
File:Lazurite.jpg|Crystals of lazurite (the main mineral in lapis lazuli) from the Sar-i Sang Mining District in Afghanistan
File:Lapis lazuli block.jpg|A polished block of lapis lazuli
File:Natural ultramarine pigment.jpg|Natural ultramarine pigment made from ground lapis lazuli. During the [[High Middle Ages|Middle Ages]] and [[Renaissance]] it was the most expensive pigment available (gold being second) and was often reserved for depicting the robes of [[Angels]] or the [[Virgin Mary]]
File:19th Century lapis lazuli and diamond pendant.jpg|19th-century lapis lazuli and diamond pendant
</gallery>