Editing Amazonite (section)

{{Short description|Green variety of microcline, tectosilicate mineral}}
{{Infobox mineral
|boxbgcolor=#9ef5d8| name = Amazonite
| category    = [[Tectosilicate]] [[minerals]], [[feldspar]] [[Mineral group|group]], [[Alkali feldspar|alkali]] series, [[microcline]] [[Mineral variety|variety]]
| image       = Amazonita1.jpeg
| imagesize   = 260px
| alt         = Photo of a turquoise [[mineral]] with beige microcline speckled within it 
| caption     = Amazonite from Brazil
| formula     = KAlSi<sub>3</sub>O<sub>8</sub>
| molweight   = 
| strunz      = 
| color       = Green, blue-green
| habit       = Prismatic
| system      = [[Triclinic crystal system|Triclinic]]
| twinning    = 
| cleavage    = Perfect
| fracture    = Uneven, splintery
| mohs        = 6.0–6.5
| tenacity    = Brittle
| luster      = Vitreous
| refractive  = 1.522–1.530
| opticalprop =
| birefringence = −0.008
| pleochroism = Absent
| dispersion  = None
| fluorescence = Weak; olive-green
| streak      = White
| gravity     = 2.56–2.58
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Translucent, opaque
| other       =[[Image:Radioactive.svg|25px]] [[Radioactive]] 14.05% ([[Potassium|K]]) 
| references  = <ref name="Walter">{{Cite book|url=https://archive.org/details/gemstonesofworld00schu/page/164|title=Gemstones of the world|last=Walter|first=Schumann|date=1997|publisher=Sterling Pub. Co|isbn=0806994614|edition=Rev. & expanded|location=New York|page=[https://archive.org/details/gemstonesofworld00schu/page/164 164]|url-access=registration|via=[[Internet Archive]]}}</ref><ref>{{cite web |last= |first= |date= |title=Radioactive Gems : ClassicGems.net |url=https://www.classicgems.net/info_Radioactive.htm |url-status=live |work=ClassicGems.net |location= |archive-url=https://web.archive.org/web/20210211013824/http://classicgems.net/info_Radioactive.htm |archive-date=2021-02-11 |access-date=2021-08-13}}</ref><ref name="bulletin">{{Cite journal|last=Schlegel|first=Dorothy McKenney|date=1957|title=Gem Stones of the United States|url=https://books.google.com/books?id=D78jhspXwxYC|journal=Geological Survey Bulletin|publisher=United States Government Publishing Office|issue=1042-G|via=[[Google Books]]}}</ref><sup>:214–215</sup>
}}

'''Amazonite''', also known as '''amazonstone''',<ref name="EB1911">{{EB1911|inline=y|wstitle=Amazon-stone|volume=1|page=791}}</ref> is a green [[tectosilicate]] [[mineral]], a variety of the potassium feldspar called [[microcline]].<ref name="EB1911"/><ref>{{cite web |url=https://www.gemdat.org/gem-184.html |title=Amazonite gemstone information |website=gemdat.org |access-date=2018-08-24 |url-status=live |archive-url=https://web.archive.org/web/20210301171608/https://www.gemdat.org/gem-184.html |archive-date=2021-03-01}}</ref><ref>{{Cite web |title=Amazonite |url=https://www.mindat.org/min-184.html}}</ref> Its [[chemical formula]] is KAlSi<sub>3</sub>O<sub>8</sub>,<ref name="Walter" /><ref name="Mindat">{{cite web |url=https://www.mindat.org/min-184.html |title=Amazonite: Amazonite mineral information and data. |website=mindat.org |access-date=13 April 2017 |url-status=live |archive-url=https://web.archive.org/web/20210514154137/https://www.mindat.org/min-184.html |archive-date=14 May 2021}}</ref> which is [[Polymorphism (materials science)|polymorphic]] to [[orthoclase]].

Its name is taken from that of the [[Amazon River]], from which green stones were formerly obtained, though it is unknown whether those stones were amazonite.<ref name="EB1911"/> Although it has been used for jewellery for well over three thousand years, as attested by archaeological finds in Middle and New Kingdom Egypt<ref>Harrell and Osman 2007</ref> and Mesopotamia, no ancient or medieval authority mentions it. It was first described as a distinct mineral only in the 18th century.<ref name="Ostrooumov">Mikhail Ostrooumov, ''Amazonite: Mineralogy, Crystal Chemistry, and Typomorphism'' (Elsevier, 2016), p. 1–12.</ref>

Green and greenish-blue varieties of potassium feldspars that are predominantly triclinic are designated as amazonite.<ref name="Pivec1981">{{Cite journal |last1=Pivec |first1=E. |last2=Ševčik |first2=J. |last3=Ulrych |first3=J. |date=December 1981 |title=Amazonite from the alkali granite of the Avdar Massif, Mongolia |journal=TMPM Tschermaks Petr. Mitt. |volume=28 |issue=4 |pages=277–283 |doi=10.1007/BF01081855|bibcode=1981TMPM...28..277P }}</ref> It has been described as a "beautiful crystallized variety of a bright verdigris-green"<ref>{{Cite EB1911|wstitle=Microcline|volume=18|page=380|ref=none}}</ref> and as possessing a "lively green colour".<ref name="EB1911"/> It is occasionally cut and used as a [[gemstone]].<ref>{{cite web|url=https://www.dmme.virginia.gov/dgmr/minerals.shtml|title=Common Minerals of Virginia|website=Virginia Department of Mines, Minerals and Energy|publisher=Commonwealth of Virginia|access-date=5 July 2019|archive-date=24 July 2021|archive-url=https://web.archive.org/web/20210724021345/https://dmme.virginia.gov/dgmr/minerals.shtml|url-status=dead}}</ref>