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{{Short description|Zirconium silicate mineral}} | {{Short description|Zirconium silicate mineral}} | ||
{{About|the mineral and gemstone}} | {{About|the mineral and gemstone}} | ||
{{Use mdy dates|date=August 2015}} | {{Use mdy dates|date=August 2015}} | ||
{{Use American English|date=March 2021}} | {{Use American English|date=March 2021}} | ||
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| diaphaneity = Transparent to opaque | | diaphaneity = Transparent to opaque | ||
| other = [[Fluorescence|Fluorescent]] and [[Image:Radioactive.svg|25px]] [[radioactive]],<br/>May form [[pleochroic halo]]s,<br/>Relief: high | | other = [[Fluorescence|Fluorescent]] and [[Image:Radioactive.svg|25px]] [[radioactive]],<br/>May form [[pleochroic halo]]s,<br/>Relief: high | ||
| references = <ref name=HBM>{{cite book |editor1-last=Anthony |editor1-first=John W. |editor2-last=Bideaux |editor2-first=Richard A. |editor3-last=Bladh |editor3-first=Kenneth W. |editor4-last=Nichols |editor4-first=Monte C. |title=Handbook of Mineralogy |publisher=[[Mineralogical Society of America]] |place=Chantilly, VA, US |chapter-url= | | references = <ref name=HBM>{{cite book |editor1-last=Anthony |editor1-first=John W. |editor2-last=Bideaux |editor2-first=Richard A. |editor3-last=Bladh |editor3-first=Kenneth W. |editor4-last=Nichols |editor4-first=Monte C. |title=Handbook of Mineralogy |publisher=[[Mineralogical Society of America]] |place=Chantilly, VA, US |chapter-url=https://rruff.geo.arizona.edu/doclib/hom/zircon.pdf |chapter=Zircon |isbn=978-0962209710 |volume=II (Silica, Silicates) |year=1995}}</ref><ref name=Mindat>{{cite web |url=https://www.mindat.org/min-4421.html |title=Zircon: Mineral information, data and localities |work=[[Mindat.org]] |access-date=October 19, 2021}}</ref><ref>{{cite web |url=https://webmineral.com/data/Zircon.shtml |title=Zircon Mineral Data |work=Webmineral|access-date=October 19, 2021}}</ref><ref name="hurlbut-klein">{{cite book|last1=Hurlbut|first1=Cornelius S. |last2=Klein |first2=Cornelis |year=1985 |title=Manual of Mineralogy |publisher=Wiley |edition=20th |isbn=0-471-80580-7}}</ref><ref>{{cite journal |url=http://www.minsocam.org/MSA/AmMin/TOC/Abstracts/2013_Abstracts/Jan13_Abstracts/Erickson_p53_13.pdf |title=Correlating planar microstructures in shocked zircon from the Vredefort Dome at multiple scales: Crystallographic modeling, external and internal imaging, and EBSD structural analysis |journal=American Mineralogist |volume=98 |pages=53–65 |year=2013 |first1=Timmons M. |last1=Erickson |first2=Aaron J. |last2=Cavosie |first3=Desmond E. |last3=Moser |first4=Ivan R. |last4=Barker |first5=Henri A. |last5=Radovan |doi=10.2138/am.2013.4165 |display-authors=3 |others=Abstract |issue=1 |bibcode=2013AmMin..98...53E |s2cid=67779734}}</ref> | ||
}} | }} | ||
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Because of their [[uranium]]<ref name="Jackson-2019">{{Cite journal |last1=Jackson |first1=Robert A. |last2=Montenari |first2=Michael |date=2019 |title=Computer modeling of Zircon (ZrSiO4)—Coffinite (USiO4) solid solutions and lead incorporation: Geological implications |url=https://www.sciencedirect.com/science/article/abs/pii/S246851781930005X |journal=Stratigraphy & Timescales |volume=4 |pages=217–227 |doi=10.1016/bs.sats.2019.08.005 |isbn=9780128175521 |s2cid=210256739 |via=Elsevier Science Direct|url-access=subscription }}</ref> and [[thorium]] content, some zircons undergo [[metamictization]]. Connected to internal radiation damage, these processes partially disrupt the crystal structure and partly explain the highly variable properties of zircon. As zircon becomes more and more modified by internal radiation damage, the density decreases, the crystal structure is compromised, and the color changes.{{sfn|Nesse|2000|pp=93–94}} | Because of their [[uranium]]<ref name="Jackson-2019">{{Cite journal |last1=Jackson |first1=Robert A. |last2=Montenari |first2=Michael |date=2019 |title=Computer modeling of Zircon (ZrSiO4)—Coffinite (USiO4) solid solutions and lead incorporation: Geological implications |url=https://www.sciencedirect.com/science/article/abs/pii/S246851781930005X |journal=Stratigraphy & Timescales |volume=4 |pages=217–227 |doi=10.1016/bs.sats.2019.08.005 |isbn=9780128175521 |s2cid=210256739 |via=Elsevier Science Direct|url-access=subscription }}</ref> and [[thorium]] content, some zircons undergo [[metamictization]]. Connected to internal radiation damage, these processes partially disrupt the crystal structure and partly explain the highly variable properties of zircon. As zircon becomes more and more modified by internal radiation damage, the density decreases, the crystal structure is compromised, and the color changes.{{sfn|Nesse|2000|pp=93–94}} | ||
Zircon occurs in many colors, including reddish brown, yellow, green, blue, gray, and colorless.<ref name=HBM/> The color of zircons can sometimes be changed by heat treatment. Common brown zircons can be transformed into colorless and blue zircons by heating to {{cvt|800|to|1000|C}}.<ref name=Gemdat>{{cite web|url= | Zircon occurs in many colors, including reddish brown, yellow, green, blue, gray, and colorless.<ref name=HBM/> The color of zircons can sometimes be changed by heat treatment. Common brown zircons can be transformed into colorless and blue zircons by heating to {{cvt|800|to|1000|C}}.<ref name=Gemdat>{{cite web|url=https://www.gemdat.org/gem-4421.html|title=Zircon gemstone information|website=www.gemdat.org|access-date=April 29, 2018}}</ref> In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years, if the crystal has sufficient trace elements to produce [[F-Center|color centers]]. Color in this red or pink series is annealed in geological conditions above temperatures of around {{cvt|400|C||}}.<ref>{{cite journal|doi=10.1016/S0040-1951(02)00054-9|title=Integration of zircon color and zircon fission-track zonation patterns in orogenic belts: Application to the Southern Alps, New Zealand |journal=Tectonophysics |volume=349 |issue=1–4 |pages=203–219 |year=2002 |last1=Garver |first1=John I. |last2=Kamp |first2=Peter J.J. |bibcode=2002Tectp.349..203G |citeseerx=10.1.1.570.3912}}</ref> | ||
Structurally, zircon consists of parallel chains of alternating silica tetrahedra (silicon ions in fourfold coordination with oxygen ions) and zirconium ions, with the large zirconium ions in eightfold coordination with oxygen ions.{{sfn|Nesse|2000|p=313}} | Structurally, zircon consists of parallel chains of alternating silica tetrahedra (silicon ions in fourfold coordination with oxygen ions) and zirconium ions, with the large zirconium ions in eightfold coordination with oxygen ions.{{sfn|Nesse|2000|p=313}} | ||
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Other applications include use in refractories and foundry casting and a growing array of specialty applications as [[zirconia]] and zirconium chemicals, including in nuclear fuel rods, catalytic fuel converters and in water and air purification systems.<ref>{{Cite web |url=http://www.mineralcommodities.com/products/ |title=Products |website=Mineral Commodities Ltd |access-date=2016-08-08 |archive-url=https://web.archive.org/web/20161007164341/http://www.mineralcommodities.com/products/ |archive-date=2016-10-07}}</ref> | Other applications include use in refractories and foundry casting and a growing array of specialty applications as [[zirconia]] and zirconium chemicals, including in nuclear fuel rods, catalytic fuel converters and in water and air purification systems.<ref>{{Cite web |url=http://www.mineralcommodities.com/products/ |title=Products |website=Mineral Commodities Ltd |access-date=2016-08-08 |archive-url=https://web.archive.org/web/20161007164341/http://www.mineralcommodities.com/products/ |archive-date=2016-10-07}}</ref> | ||
[[Ford Motor Company]] used a sand casting method known as the ''Cosworth Casting Method'' for the cylinder heads of its [[Ford Duratec V6 engine|Duratec V6 engine]]. The process, developed by noted scientist [[John Campbell (casting scientist)|John Campbell]] used zircon as its casting aggregate to improve material uniformity and create dimensional accuracy, high strength, and a dense, low- or no-porosity structure.<ref name="jag"/><ref name="casting">{{cite web | [[Ford Motor Company]] used a sand casting method known as the ''Cosworth Casting Method'' for the cylinder heads of its [[Ford Duratec V6 engine|Duratec V6 engine]]. The process, developed by noted scientist [[John Campbell (casting scientist)|John Campbell]] used zircon as its casting aggregate to improve material uniformity and create dimensional accuracy, high strength, and a dense, low- or no-porosity structure.<ref name="jag">{{cite web | ||
|title = Jaguar AJ-V6 engine tech guide | |||
|publisher = Prestige and Performance Car | |||
|author = Paul Wager | |||
|date = October 18, 2023 | |||
|url = https://prestigeandperformancecar.com/jaguar/jaguar-aj-v6-engine-tech-guide/}}</ref><ref name="casting">{{cite web | |||
|title = Cosworth sand casting process | |title = Cosworth sand casting process | ||
|publisher = Giesserei Lexikon | |publisher = Giesserei Lexikon | ||
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Most gem-grade zircons show a high degree of [[birefringence]] which, on stones cut with a table and pavilion cuts (i.e., nearly all cut stones), can be seen as the apparent doubling-up of the latter when viewed through the former, and this characteristic can be used to distinguish them from diamonds and cubic zirconias (CZ) as well as soda-lime glass, none of which show this characteristic. However, some zircons from Sri Lanka display only weak or no birefringence at all, and some other Sri Lanka stones may show clear birefringence in one place and little or none in another part of the same cut stone.<ref>{{cite book|pages=562–563|author=L.J. Spencer|publisher=John Murray|date=1905|title=Report of the Seventy-Fourth Meeting of the British Association for the Advancement of Science}}</ref> Other gemstones also display birefringence, so while the presence of this characteristic may help distinguish a given zircon from a diamond or a CZ, it will not help distinguish it from, for example, a [[topaz]] gemstone. The high specific gravity of zircon, however, can usually separate it from any other gem and is simple to test. | Most gem-grade zircons show a high degree of [[birefringence]] which, on stones cut with a table and pavilion cuts (i.e., nearly all cut stones), can be seen as the apparent doubling-up of the latter when viewed through the former, and this characteristic can be used to distinguish them from diamonds and cubic zirconias (CZ) as well as soda-lime glass, none of which show this characteristic. However, some zircons from Sri Lanka display only weak or no birefringence at all, and some other Sri Lanka stones may show clear birefringence in one place and little or none in another part of the same cut stone.<ref>{{cite book|pages=562–563|author=L.J. Spencer|publisher=John Murray|date=1905|title=Report of the Seventy-Fourth Meeting of the British Association for the Advancement of Science}}</ref> Other gemstones also display birefringence, so while the presence of this characteristic may help distinguish a given zircon from a diamond or a CZ, it will not help distinguish it from, for example, a [[topaz]] gemstone. The high specific gravity of zircon, however, can usually separate it from any other gem and is simple to test. | ||
Also, birefringence depends on the cut of the stone in relation to its [[optical axis]]. If a zircon is cut with this axis perpendicular to its table, birefringence may be reduced to undetectable levels unless viewed with a jeweler's [[loupe]] or other magnifying optics. The highest grade zircons are cut to minimize birefringence.<ref name=guide>{{cite web |url= | Also, birefringence depends on the cut of the stone in relation to its [[optical axis]]. If a zircon is cut with this axis perpendicular to its table, birefringence may be reduced to undetectable levels unless viewed with a jeweler's [[loupe]] or other magnifying optics. The highest grade zircons are cut to minimize birefringence.<ref name=guide>{{cite web |url=https://www.gemstones-guide.com/Zircon.html#Physical_Optical_Properties_of_Zircon|title=Physical & Optical Properties of Zircon |work=Colored Gemstones Guide|access-date=October 19, 2021}}</ref> | ||
The value of a zircon gem depends largely on its color, clarity, and size. Prior to World War II, blue zircons (the most valuable color) were available from many gemstone suppliers in sizes between 15 and 25 carats; since then, stones even as large as 10 carats have become very scarce, especially in the most desirable color varieties.<ref name=guide/> | The value of a zircon gem depends largely on its color, clarity, and size. Prior to World War II, blue zircons (the most valuable color) were available from many gemstone suppliers in sizes between 15 and 25 carats; since then, stones even as large as 10 carats have become very scarce, especially in the most desirable color varieties.<ref name=guide/> | ||
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==Occurrence== | ==Occurrence== | ||
[[Image:Zirconium mineral concentrates - world production trend.svg|thumb|left|World production trend of zirconium mineral concentrates]] | [[Image:Zirconium mineral concentrates - world production trend.svg|thumb|left|World production trend of zirconium mineral concentrates]] | ||
Zircon is a common accessory to trace mineral constituent of all kinds of igneous rocks, but particularly [[granite]] and [[felsic]] igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands.{{sfn|Nesse|2000|pp=313–314}}{{sfn|Hurlbut|Klein|1985|p=454}} Zircon can occasionally be found as a trace mineral in [[ultrapotassic igneous rocks]] such as [[kimberlite]]s, carbonatites, and lamprophyre, owing to the unusual magma genesis of these rocks.<ref>{{Cite journal |last1=Shumlyanskyy |first1=Leonid V. |last2=Kamenetsky |first2=Vadim S. |last3=Tsymbal |first3=Stepan M. |last4=Wilde |first4=Simon A. |last5=Nemchin |first5=Alexander A. |last6=Ernst |first6=Richard E. |last7=Shumlianska |first7=Liudmyla O. |date=2021-12-15 |title=Zircon megacrysts from Devonian kimberlites of the Azov Domain, Eastern part of the Ukrainian Shield: Implications for the origin and evolution of kimberlite melts |url=https://www.sciencedirect.com/science/article/abs/pii/S0024493721005715 |journal=Lithos |volume=406-407 | | Zircon is a common accessory to trace mineral constituent of all kinds of igneous rocks, but particularly [[granite]] and [[felsic]] igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands.{{sfn|Nesse|2000|pp=313–314}}{{sfn|Hurlbut|Klein|1985|p=454}} Zircon can occasionally be found as a trace mineral in [[ultrapotassic igneous rocks]] such as [[kimberlite]]s, carbonatites, and lamprophyre, owing to the unusual magma genesis of these rocks.<ref>{{Cite journal |last1=Shumlyanskyy |first1=Leonid V. |last2=Kamenetsky |first2=Vadim S. |last3=Tsymbal |first3=Stepan M. |last4=Wilde |first4=Simon A. |last5=Nemchin |first5=Alexander A. |last6=Ernst |first6=Richard E. |last7=Shumlianska |first7=Liudmyla O. |date=2021-12-15 |title=Zircon megacrysts from Devonian kimberlites of the Azov Domain, Eastern part of the Ukrainian Shield: Implications for the origin and evolution of kimberlite melts |url=https://www.sciencedirect.com/science/article/abs/pii/S0024493721005715 |journal=Lithos |volume=406-407 |article-number=106528 |doi=10.1016/j.lithos.2021.106528 |bibcode=2021Litho.40606528S |issn=0024-4937|url-access=subscription }}</ref><ref>{{Cite journal |last1=Zaccaria |first1=Daria |last2=Vicentini |first2=Noemi |last3=Perna |first3=Maria Grazia |last4=Rosatelli |first4=Gianluigi |last5=Sharygin |first5=Victor V. |last6=Humphreys-Williams |first6=Emma |last7=Brownscombe |first7=Will |last8=Stoppa |first8=Francesco |date=2021-09-30 |title=Lamprophyre as the Source of Zircon in the Veneto Region, Italy |journal=Minerals |language=en |volume=11 |issue=10 |pages=1081 |doi=10.3390/min11101081 |doi-access=free |bibcode=2021Mine...11.1081Z |issn=2075-163X }}</ref> | ||
Zircon forms economic concentrations within [[heavy mineral sands ore deposits]], within certain [[pegmatite]]s, and within some rare alkaline volcanic rocks | Zircon forms economic concentrations within [[heavy mineral sands ore deposits]], within certain [[pegmatite]]s, and within some rare alkaline volcanic rocks (for example the Toongi Trachyte in [[Dubbo]], Australia)<ref>{{cite web|url=http://www.alkane.com.au/images/pdf/Media/20141023.pdf|title=Dubbo Zirconia Project Fact Sheet June 2014|date=June 2007 |author=Staff|work=Alkane Resources Limited|access-date=2007-09-10|archive-url=https://web.archive.org/web/20080228054038/http://www.alkane.com.au/projects/nsw/dubbo/DZP%20Summary%20June07.pdf|archive-date=2008-02-28}}</ref> in association with the zirconium-hafnium minerals [[eudialyte]] and armstrongite. | ||
Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR ([[economic demonstrated resources]]) for the mineral.<ref>{{Cite web|url=http://www.zircon-association.org/Websites/zircon/images/Resources/the-mineral-sands-industry-factbook-(feb-2014).pdf|title=The Mineral Sands Industry Factbook|archive-url=https://web.archive.org/web/20160818142054/http://www.zircon-association.org/Websites/zircon/images/Resources/the-mineral-sands-industry-factbook-(feb-2014).pdf|archive-date=2016-08-18}}</ref> South Africa is Africa's main producer, with 30% of world production, second after Australia.<ref>{{Cite web |url=https://www.mbendi.com/indy/ming/hvym/af/p0005.htm|title=Heavy Minerals Mining in Africa – Titanium And Zirconium|access-date=2016-08-08 |archive-url=https://web.archive.org/web/20080528050951/http://www.mbendi.co.za/indy/ming/hvym/af/p0005.htm |archive-date=2008-05-28}}</ref> | Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR ([[economic demonstrated resources]]) for the mineral.<ref>{{Cite web|url=http://www.zircon-association.org/Websites/zircon/images/Resources/the-mineral-sands-industry-factbook-(feb-2014).pdf|title=The Mineral Sands Industry Factbook|archive-url=https://web.archive.org/web/20160818142054/http://www.zircon-association.org/Websites/zircon/images/Resources/the-mineral-sands-industry-factbook-(feb-2014).pdf|archive-date=2016-08-18}}</ref> South Africa is Africa's main producer, with 30% of world production, second after Australia.<ref>{{Cite web |url=https://www.mbendi.com/indy/ming/hvym/af/p0005.htm|title=Heavy Minerals Mining in Africa – Titanium And Zirconium|access-date=2016-08-08 |archive-url=https://web.archive.org/web/20080528050951/http://www.mbendi.co.za/indy/ming/hvym/af/p0005.htm |archive-date=2008-05-28}}</ref> | ||
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==Radiometric dating== | ==Radiometric dating== | ||
[[File:Zircon grain (CL-SEM imaging).tiff|thumb|SEM-CL image of Zircon grain showing zonations and poly-cycles (core-rim structure)]] | [[File:Zircon grain (CL-SEM imaging).tiff|thumb|SEM-CL image of Zircon grain showing zonations and poly-cycles (core-rim structure)]] | ||
Zircon has played an important role during the evolution of [[radiometric dating]]. Zircons contain trace amounts of [[uranium]] and [[thorium]] (from 10 [[Parts per million|ppm]] up to 1 wt%)<ref name="Jackson-2019" /> and can be dated using several modern analytical techniques. Because zircons can survive geologic processes like [[erosion]], transport, and even high-grade [[metamorphism]], they contain a rich and varied record of geological processes. Currently, zircons are typically dated by [[ | Zircon has played an important role during the evolution of [[radiometric dating]]. Zircons contain trace amounts of [[uranium]] and [[thorium]] (from 10 [[Parts per million|ppm]] up to 1 wt%)<ref name="Jackson-2019" /> and can be dated using several modern analytical techniques. Because zircons can survive geologic processes like [[erosion]], transport, and even high-grade [[metamorphism]], they contain a rich and varied record of geological processes. Currently, zircons are typically dated by [[uranium–lead dating|uranium–lead]] (U–Pb), [[fission track dating|fission-track]], and U+Th/He techniques. Imaging the cathodoluminescence emission from fast electrons can be used as a prescreening tool for high-resolution [[Secondary ion mass spectrometry|secondary-ion mass spectrometry]] (SIMS) to image the zonation pattern and identify regions of interest for isotope analysis. This is done using an integrated cathodoluminescence and scanning electron microscope.<ref>{{Cite web|url=https://request.delmic.com/zircon-application-note |title=Zircons – Application Note |website=DELMIC |language=en |access-date=2017-02-10}}</ref> [[Detrital zircon geochronology|Zircons in sedimentary rock]] can identify the sediment source.<ref>{{cite journal |last1=Cawood |first1=P.A. |last2=Hawkesworth |first2=C.J. |last3=Dhuime |first3=B. |title=Detrital zircon record and tectonic setting |journal=Geology |date=October 2012 |volume=40 |issue=10 |pages=875–878 |doi=10.1130/G32945.1 |bibcode=2012Geo....40..875C|doi-access=free|hdl=10023/3575 |hdl-access=free }}</ref> | ||
Zircons from [[Jack Hills]] in the [[Narryer Gneiss terrane]], [[Yilgarn craton]], [[Western Australia]], have yielded [[ | Zircons from [[Jack Hills]] in the [[Narryer Gneiss terrane]], [[Yilgarn craton]], [[Western Australia]], have yielded [[uranium–lead dating|U–Pb]] ages up to 4.404 billion years,<ref name="Wilde">{{cite journal |doi=10.1038/35051550 |pmid=11196637|title=Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago |journal=Nature |volume=409|issue=6817|pages=175–178|year=2001|last1=Wilde|first1=Simon A.|last2=Valley|first2=John W. |last3=Peck |first3=William H.|last4=Graham|first4=Colin M.|bibcode=2001Natur.409..175W|s2cid=4319774}}</ref> interpreted to be the age of crystallization, making them the [[oldest rock|oldest minerals]] so far dated on Earth. In addition, the [[oxygen]] [[isotope|isotopic]] compositions of some of these zircons have been interpreted to indicate that more than 4.3 billion years ago there was already liquid water on the surface of the Earth.<ref name="Wilde" /><ref>{{cite journal |doi=10.1038/35051557 |pmid=11196638 |title=Oxygen-isotope evidence from ancient zircons for liquid water at the Earth's surface 4,300 Myr ago |journal=Nature |volume=409|issue=6817|pages=178–181|year=2001|last1=Mojzsis|first1=Stephen J. |last2=Harrison |first2=T. Mark |last3=Pidgeon|first3=Robert T.|bibcode=2001Natur.409..178M |s2cid=2819082}}</ref><ref>{{Cite journal |last1=Valley |first1=JW |last2=Peck |first2=WH |last3=King |first3=EM |last4=Wilde |first4=SA |date=2002 |title=A cool early Earth |journal=Geology |volume=30 |issue=4 |pages=351–354|doi=10.1130/0091-7613(2002)030<0351:ACEE>2.0.CO;2 |bibcode=2002Geo....30..351V }}</ref><ref>{{Cite journal |last1=Valley |first1=JW |last2=Lackey |first2=JS |last3=Cavosie |first3=AJ |date=2005 |title=4.4 billion years of crustal maturation: Oxygen isotopes in magmatic zircon. |journal=Contributions to Mineralogy and Petrology |volume=150 |pages=561–580|doi=10.1007/s00410-005-0025-8 |s2cid=53118854 }}</ref> This interpretation is supported by additional trace element data,<ref>{{cite journal|doi=10.1016/j.epsl.2008.05.032|title=Lithium in Jack Hills zircons: Evidence for extensive weathering of Earth's earliest crust|journal=Earth and Planetary Science Letters|volume=272|issue=3–4|pages=666–676 |year=2008 |last1=Ushikubo|first1=Takayuki|last2=Kita|first2=Noriko T.|last3=Cavosie|first3=Aaron J. |last4=Wilde |first4=Simon A.|last5=Rudnick|first5=Roberta L.|last6=Valley|first6=John W.|bibcode=2008E&PSL.272..666U}}</ref><ref>{{cite news |url=http://www.physorg.com/news132583481.html|title=Ancient mineral shows early Earth climate tough on continents |publisher=Physorg.com |date=June 13, 2008}}</ref> but is also the subject of debate.<ref>{{cite journal |doi=10.1016/j.epsl.2006.01.054 |title=Re-evaluation of the origin and evolution of >4.2 Ga zircons from the Jack Hills metasedimentary rocks|journal=Earth and Planetary Science Letters|volume=244|issue=1–2|pages=218–233 |year=2006 |last1=Nemchin |first1=A.|last2=Pidgeon |first2=R.|last3=Whitehouse|first3=M.|bibcode=2006E&PSL.244..218N}}</ref><ref>{{cite journal |doi=10.1016/j.epsl.2005.04.028 |title=Magmatic δ<sup>18</sup>O in 4400–3900 Ma detrital zircons: A record of the alteration and recycling of crust in the Early Archean |journal=Earth and Planetary Science Letters|volume=235|issue=3–4|pages=663–681|year=2005|last1=Cavosie|first1=A.J.|last2=Valley|first2=J.W.|last3=Wilde|first3=S.A.|bibcode=2005E&PSL.235..663C}}</ref><ref>{{Cite journal |last1=Valley |first1=JW |last2=Cavosie |first2=AJ |last3=Ushikobo |first3=T |last4=Reinhardt |last5=Lawrence |first5=DF |last6=Larson |first6=DJ |last7=Clifton |first7=PH |last8=Kelly |first8=TF |last9=Wilde |first9=SA |last10=Moser |first10=DE |last11=Spicuzza |first11=MJ |date=2014 |title=Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography |journal=Nature Geoscience |volume=7 |issue=3 |pages=219–223|doi=10.1038/ngeo2075 |bibcode=2014NatGe...7..219V }}</ref> In 2015, "remains of [[Biotic material|biotic life]]" were found in 4.1-billion-year-old rocks in the Jack Hills of Western Australia.<ref name="AP-20151019">{{cite news|last=Borenstein|first=Seth|title=Hints of life on what was thought to be desolate early Earth|url=http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html |date=19 October 2015|work=[[Excite (web portal)|Excite]]|location=Yonkers, NY|publisher=[[Mindspark Interactive Network]]|agency=[[Associated Press]]|url-status=dead|archive-url=https://web.archive.org/web/20151023200248/http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html |archive-date=23 October 2015|access-date=8 October 2018}}</ref><ref name="PNAS-20151014-pdf">{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnke|first2=Patrick|last3=Harrison|first3=T. Mark|last4=Mao|first4=Wendy L.|author-link4=Wendy Mao |year=2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|journal=Proceedings of the National Academy of Sciences |volume=112|issue=47|pages=14518–14521 |bibcode=2015PNAS..11214518B |doi=10.1073/pnas.1517557112 |pmc=4664351 |pmid=26483481|doi-access=free}}</ref> According to one of the researchers, "If [[life]] arose relatively quickly on [[Earth]] ... then it could be common in the [[universe]]."<ref name="AP-20151019" /> | ||
==Similar minerals== | ==Similar minerals== | ||
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*{{cite journal|author=A. N. Halliday|year=2001|title=In the beginning…|journal=Nature|volume=409|pages=144–145|doi=10.1038/35051685|pmid=11196624|issue=6817|s2cid=4339433}} | *{{cite journal|author=A. N. Halliday|year=2001|title=In the beginning…|journal=Nature|volume=409|pages=144–145|doi=10.1038/35051685|pmid=11196624|issue=6817|s2cid=4339433}} | ||
*{{cite journal|author=Hermann Köhler|year=1970|title=Die Änderung der Zirkonmorphologie mit dem Differentiationsgrad eines Granits|journal=Neues Jahrbuch für Mineralogie - Monatshefte|volume=9|pages=405–420}} | *{{cite journal|author=Hermann Köhler|year=1970|title=Die Änderung der Zirkonmorphologie mit dem Differentiationsgrad eines Granits|journal=Neues Jahrbuch für Mineralogie - Monatshefte|volume=9|pages=405–420}} | ||
*{{cite journal|author1=K. Mezger|author2=E. J. Krogstad|name-list-style=amp|year=1997|title=Interpretation of discordant | *{{cite journal|author1=K. Mezger|author2=E. J. Krogstad|name-list-style=amp|year=1997|title=Interpretation of discordant U–Pb zircon ages: An evaluation|journal=Journal of Metamorphic Geology|volume=15|issue=1|pages=127–140|doi=10.1111/j.1525-1314.1997.00008.x|bibcode=1997JMetG..15..127M|s2cid=129846813 }} | ||
*{{cite journal|author=J. P. Pupin|year=1980|title=Zircon and Granite petrology|journal=Contributions to Mineralogy and Petrology|volume=73|pages=207–220|doi=10.1007/BF00381441|bibcode=1980CoMP...73..207P|issue=3|s2cid=96470918}} | *{{cite journal|author=J. P. Pupin|year=1980|title=Zircon and Granite petrology|journal=Contributions to Mineralogy and Petrology|volume=73|pages=207–220|doi=10.1007/BF00381441|bibcode=1980CoMP...73..207P|issue=3|s2cid=96470918}} | ||
*{{cite journal|author=Gunnar Ries|year=2001|title=Zirkon als akzessorisches Mineral|journal=Aufschluss|volume=52|pages=381–383}} | *{{cite journal|author=Gunnar Ries|year=2001|title=Zirkon als akzessorisches Mineral|journal=Aufschluss|volume=52|pages=381–383}} | ||
| Line 152: | Line 156: | ||
*[http://www.geology.wisc.edu/zircon/zircon_home.html Geochemistry of old zircons]. {{Webarchive|url=https://web.archive.org/web/20070412195510/http://www.geology.wisc.edu/zircon/zircon_home.html |date=April 12, 2007 }}. | *[http://www.geology.wisc.edu/zircon/zircon_home.html Geochemistry of old zircons]. {{Webarchive|url=https://web.archive.org/web/20070412195510/http://www.geology.wisc.edu/zircon/zircon_home.html |date=April 12, 2007 }}. | ||
*[https://web.archive.org/web/20050407220144/http://mineral.galleries.com/minerals/silicate/zircon/zircon.htm Mineral galleries] (archived 7 April 2005) | *[https://web.archive.org/web/20050407220144/http://mineral.galleries.com/minerals/silicate/zircon/zircon.htm Mineral galleries] (archived 7 April 2005) | ||
*[ | *[https://www.gia.edu/zircon ''GIA Gem Encyclopedia'' – Zircon] Online articles and information on zircon history, lore, and research | ||
*[http://www.zircon-association.org/ Zircon Industry Association] | *[http://www.zircon-association.org/ Zircon Industry Association] | ||
*All About [https://myratna.com/gemstone/natural-zircon Natural Zircon] | *All About [https://myratna.com/gemstone/natural-zircon Natural Zircon] | ||
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[[Category:Nesosilicates]] | [[Category:Nesosilicates]] | ||
[[Category:Refractory materials]] | [[Category:Refractory materials]] | ||
[[Category:Radioactive | [[Category:Radioactive minerals]] | ||
[[Category:Gemstones]] | [[Category:Gemstones]] | ||
[[Category:Tetragonal minerals]] | [[Category:Tetragonal minerals]] | ||
[[Category:Minerals in space group 141]] | [[Category:Minerals in space group 141]] | ||
[[Category:Luminescent minerals]] | [[Category:Luminescent minerals]] | ||
Latest revision as of 19:00, 14 November 2025
Template:Short description Script error: No such module "about". Template:Use mdy dates Template:Use American English Template:Infobox mineral
Zircon (Template:IPAc-en)[1][2][3] is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is ZrSiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.[4]
The name derives from the Persian zargun, meaning "gold-hued".[5] This word is changed into "jargoon", a term applied to light-colored zircons. The English word "zircon" is derived from Zirkon, which is the German adaptation of this word.[6] Yellow, orange, and red zircon is also known as "hyacinth",[7] from the flower hyacinthus, whose name is of Ancient Greek origin.
Properties
Zircon is common in the crust of Earth. It occurs as a common accessory mineral in igneous rocks (as primary crystallization products), in metamorphic rocks and as detrital grains in sedimentary rocks.[8] Large zircon crystals are rare. Their average size in granite rocks is about Template:Cvt, but they can also grow to sizes of several cm, especially in mafic pegmatites and carbonatites.[8] Zircon is fairly hard (with a Mohs hardness of 7.5) and chemically stable, and so is highly resistant to weathering. It also is resistant to heat, so that detrital zircon grains are sometimes preserved in igneous rocks formed from melted sediments.[9] Its resistance to weathering, together with its relatively high specific gravity (4.68), make it an important component of the heavy mineral fraction of sandstones.[10]
Because of their uranium[11] and thorium content, some zircons undergo metamictization. Connected to internal radiation damage, these processes partially disrupt the crystal structure and partly explain the highly variable properties of zircon. As zircon becomes more and more modified by internal radiation damage, the density decreases, the crystal structure is compromised, and the color changes.Template:Sfn
Zircon occurs in many colors, including reddish brown, yellow, green, blue, gray, and colorless.[8] The color of zircons can sometimes be changed by heat treatment. Common brown zircons can be transformed into colorless and blue zircons by heating to Template:Cvt.[12] In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years, if the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above temperatures of around Template:Cvt.[13]
Structurally, zircon consists of parallel chains of alternating silica tetrahedra (silicon ions in fourfold coordination with oxygen ions) and zirconium ions, with the large zirconium ions in eightfold coordination with oxygen ions.Template:Sfn
Applications
Zircon is mainly consumed as an opacifier, and has been known to be used in the decorative ceramics industry.[14] It is also the principal precursor not only to metallic zirconium, although this application is small, but also to all compounds of zirconium including zirconium dioxide (Template:Chem2), an important refractory oxide with a melting point of Template:Cvt.[15]
Other applications include use in refractories and foundry casting and a growing array of specialty applications as zirconia and zirconium chemicals, including in nuclear fuel rods, catalytic fuel converters and in water and air purification systems.[16]
Ford Motor Company used a sand casting method known as the Cosworth Casting Method for the cylinder heads of its Duratec V6 engine. The process, developed by noted scientist John Campbell used zircon as its casting aggregate to improve material uniformity and create dimensional accuracy, high strength, and a dense, low- or no-porosity structure.[17][18]
Zircon is one of the key minerals used by geologists for geochronology.Template:Sfn
Zircon is a part of the ZTR index to classify highly-weathered sediments.[19]
Gemstone
Transparent zircon is a well-known form of semi-precious gemstone, favored for its high specific gravity (between 4.2 and 4.86) and adamantine luster. Because of its high refractive index (1.92) it has sometimes been used as a substitute for diamond, though it does not display quite the same play of color as a diamond. Zircon is one of the heaviest types of gemstone.[20] Its Mohs hardness is between that of quartz and topaz, at 7.5 on the 10 point scale, though below that of the similar manmade stone cubic zirconia (8-8.5). Zircons may sometimes lose their inherent color after long exposure to bright sunlight, which is unusual in a gemstone. It is immune to acid attack except by sulfuric acid and then only when ground into a fine powder.[21]
Most gem-grade zircons show a high degree of birefringence which, on stones cut with a table and pavilion cuts (i.e., nearly all cut stones), can be seen as the apparent doubling-up of the latter when viewed through the former, and this characteristic can be used to distinguish them from diamonds and cubic zirconias (CZ) as well as soda-lime glass, none of which show this characteristic. However, some zircons from Sri Lanka display only weak or no birefringence at all, and some other Sri Lanka stones may show clear birefringence in one place and little or none in another part of the same cut stone.[22] Other gemstones also display birefringence, so while the presence of this characteristic may help distinguish a given zircon from a diamond or a CZ, it will not help distinguish it from, for example, a topaz gemstone. The high specific gravity of zircon, however, can usually separate it from any other gem and is simple to test.
Also, birefringence depends on the cut of the stone in relation to its optical axis. If a zircon is cut with this axis perpendicular to its table, birefringence may be reduced to undetectable levels unless viewed with a jeweler's loupe or other magnifying optics. The highest grade zircons are cut to minimize birefringence.[23]
The value of a zircon gem depends largely on its color, clarity, and size. Prior to World War II, blue zircons (the most valuable color) were available from many gemstone suppliers in sizes between 15 and 25 carats; since then, stones even as large as 10 carats have become very scarce, especially in the most desirable color varieties.[23]
Synthetic zircons have been created in laboratories.[24] They are occasionally used in jewellery such as earrings. Zircons are sometimes imitated by spinel and synthetic sapphire, but are not difficult to distinguish from them with simple tools.
Zircon from Ratanakiri province in Cambodia is heat treated to produce blue zircon gemstones, sometimes referred to by the trade name cambolite.[25]
Occurrence
Zircon is a common accessory to trace mineral constituent of all kinds of igneous rocks, but particularly granite and felsic igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands.Template:SfnTemplate:Sfn Zircon can occasionally be found as a trace mineral in ultrapotassic igneous rocks such as kimberlites, carbonatites, and lamprophyre, owing to the unusual magma genesis of these rocks.[26][27]
Zircon forms economic concentrations within heavy mineral sands ore deposits, within certain pegmatites, and within some rare alkaline volcanic rocks (for example the Toongi Trachyte in Dubbo, Australia)[28] in association with the zirconium-hafnium minerals eudialyte and armstrongite.
Australia leads the world in zircon mining, producing 37% of the world total and accounting for 40% of world EDR (economic demonstrated resources) for the mineral.[29] South Africa is Africa's main producer, with 30% of world production, second after Australia.[30]
Radiometric dating
Zircon has played an important role during the evolution of radiometric dating. Zircons contain trace amounts of uranium and thorium (from 10 ppm up to 1 wt%)[11] and can be dated using several modern analytical techniques. Because zircons can survive geologic processes like erosion, transport, and even high-grade metamorphism, they contain a rich and varied record of geological processes. Currently, zircons are typically dated by uranium–lead (U–Pb), fission-track, and U+Th/He techniques. Imaging the cathodoluminescence emission from fast electrons can be used as a prescreening tool for high-resolution secondary-ion mass spectrometry (SIMS) to image the zonation pattern and identify regions of interest for isotope analysis. This is done using an integrated cathodoluminescence and scanning electron microscope.[31] Zircons in sedimentary rock can identify the sediment source.[32]
Zircons from Jack Hills in the Narryer Gneiss terrane, Yilgarn craton, Western Australia, have yielded U–Pb ages up to 4.404 billion years,[33] interpreted to be the age of crystallization, making them the oldest minerals so far dated on Earth. In addition, the oxygen isotopic compositions of some of these zircons have been interpreted to indicate that more than 4.3 billion years ago there was already liquid water on the surface of the Earth.[33][34][35][36] This interpretation is supported by additional trace element data,[37][38] but is also the subject of debate.[39][40][41] In 2015, "remains of biotic life" were found in 4.1-billion-year-old rocks in the Jack Hills of Western Australia.[42][43] According to one of the researchers, "If life arose relatively quickly on Earth ... then it could be common in the universe."[42]
Similar minerals
Hafnon (Template:Chem2), xenotime (Template:Chem2), béhierite, schiavinatoite (Template:Chem2), thorite (Template:Chem2), and coffinite (Template:Chem2)[11] all share the same crystal structure (IVX IVY O4, IIIX VY O4 in the case of xenotime) as zircon.
Gallery
-
Crystal structure of zircon
-
Unit cell of zircon
-
Scanning electron microscope image of zircon
-
Unusual olive-green zircon
-
Cluster of three compound crystals of zircon
See also
- Baddeleyite, Template:Chem2
- Cathodoluminescence microscope
- Cool Early Earth
- Earliest known life forms
- Hadean zircon
- Heavy mineral sands ore deposits
- History of Earth
- Ilmenite
- Cerium anomaly
References
Further reading
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External links
- Geochemistry of old zircons. Template:Webarchive.
- Mineral galleries (archived 7 April 2005)
- GIA Gem Encyclopedia – Zircon Online articles and information on zircon history, lore, and research
- Zircon Industry Association
- All About Natural Zircon
Template:Jewellery Template:Authority control
- ↑ Template:Cite Collins Dictionary
- ↑ Template:Cite American Heritage Dictionary
- ↑ Template:Cite Merriam-Webster
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