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'{{short description|Silicon carbide mineral}} {{Infobox mineral | name = Moissanite | category = [[Mineral]] species | image = Moissanite-USGS-20-1001d-14x-.jpg | imagesize = 260px | caption = | formula = SiC | IMAsymbol = Moi<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = | strunz = 1.DA.05 | system = 6H polytype, most common: [[Hexagonal crystal system|hexagonal]] | class = 6H polytype: dihexagonal pyramidal (6mm) <br/>[[H-M symbol]]: (6mm) | symmetry = 6H polytype: ''P6''₃mc | color = Colorless, green, yellow | habit = Generally found as inclusions in other minerals | twinning = | cleavage = (0001) indistinct | fracture = Conchoidal – fractures developed in brittle materials characterized by smoothly curving surfaces, e.g., quartz | mohs = 9.25 | luster = Adamantine to metallic | refractive = n_ω = 2.654 n_ε = 2.967 | opticalprop = | birefringence = 0.313 (6H form) | dispersion = 0.104 | fluorescence= Orange-red | pleochroism = | streak = Greenish gray | gravity = 3.218–3.22 | melt = 2730 °C (decomposes) | fusibility = | diagnostic = | solubility = None | diaphaneity = Transparent | other = Not radioactive, non-magnetic | references = <ref>[http://www.webmineral.com/data/Moissanite.shtml Moissanite]. Webmineral</ref><ref>[http://www.mindat.org/min-2743.html Moissanite]. Mindat</ref><ref name=Handbook>Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W. and Nichols, Monte C. (eds.) [http://www.handbookofmineralogy.org/pdfs/moissanite.pdf "Moissanite"] {{Webarchive|url=https://web.archive.org/web/20160303203542/http://www.handbookofmineralogy.org/pdfs/moissanite.pdf |date=2016-03-03 }}. ''Handbook of Mineralogy''. Mineralogical Society of America</ref> }} '''Moissanite''' ({{IPAc-en|ˈ|m|ɔɪ|s|ə|ˌ|n|aɪ|t}})<ref>{{OED|Moissanite}}</ref> is naturally occurring [[silicon carbide]] and its various crystalline [[polymorphism (materials science)|polymorphs]]. It has the chemical formula '''SiC''' and is a rare [[mineral]], discovered by the French chemist [[Henri Moissan]] in 1893. Silicon carbide or moissanite is useful for commercial and industrial applications due to its [[hardness]], [[optical properties]] and [[thermal conductivity]]. Starlight'''™''' is a premium brand of Moissanite. Starlight'''™''' Moissanite is the only Moissanite with a lab certificate from an Assay Office. Established 31 August 1773 this laboratory is older than the GIA. Each stone over 5mm in size is individually certificates buy the Assay office and a individuality referenced in their archives and on a certificate. The unique reference number and the Starlight'''™''' logo is inscribed on the bezel of the stone. == Background == The mineral moissanite was discovered by Henri Moissan while examining rock samples from a [[meteor crater]] located in [[Canyon Diablo (canyon)|Canyon Diablo]], [[Arizona]], in 1893. At first, he mistakenly identified the crystals as [[diamond]]s, but in 1904 he identified the crystals as silicon carbide.<ref name = xu>{{cite journal|author = Xu J. |author2=Mao H. |name-list-style=amp |date = 2000| title = Moissanite: A window for high-pressure experiments|journal = [[Science (journal)|Science]]|volume = 290| pages = 783–787|doi = 10.1126/science.290.5492.783|pmid=11052937|issue=5492|bibcode = 2000Sci...290..783X }}</ref><ref>{{cite journal|author = Moissan, Henri |title = Nouvelles recherches sur la météorité de Cañon Diablo|date = 1904|journal = [[Comptes rendus]]|volume = 139| pages = 773–786| url = http://gallica.bnf.fr/ark:/12148/bpt6k30930/f773.table}}</ref> Artificial silicon carbide had been synthesized in the lab by [[Edward_Goodrich_Acheson|Edward G. Acheson]] in 1891, just two years before Moissan's discovery.<ref>{{cite web|last1=Smith|first1=Kady|title=History and Applications of Silicon Carbide|url=http://blog.moissaniteco.com/history-and-applications-of-silicon-carbide/|publisher=Moissanite & Co|access-date=2 February 2016}}</ref> The mineral form of silicon carbide was named in honor of Moissan later on in his life. == Geological occurrence == In its natural form, moissanite remains very rare. Until the 1950s, no other source for moissanite other than as [[presolar grains]] in [[carbonaceous chondrite]] [[meteorites]]<ref name = sch>{{cite journal|author = Yokoyama, T. | author2=Rai, V. K. | author3=Alexander, C. M. O’D. | author4=Lewis, R. S. | author5=Carlson, R. W. | author6=Shirey, S. B. | author7=Thiemens, M. H. | author8=Walker, R. J. |title = Nucleosynthetic Os Isotopic Anomalies in Carbonaceous Chondrites|url=http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1151.pdf|journal = 38th Lunar and Planetary Science Conference |date=March 2007| issue=1338 | page=1151 | bibcode=2007LPI....38.1151Y }}</ref> had been encountered. Then, in 1958, moissanite was found in the [[upper mantle (Earth)|upper mantle]] [[Green River Formation]] in [[Wyoming]] and, the following year, as [[Inclusion (mineral)|inclusions]] in the [[ultramafic rock]] [[kimberlite]] from a diamond mine in [[Sakha Republic|Yakutia]] in the Russian Far East.<ref>{{cite journal|journal = American Mineralogist|volume =48|pages = 620–634|date = 1963|title = Natural α–Silicon Carbide|author = Bauer, J.|author2=Fiala, J. |author3=Hřichová, R. |url=http://www.minsocam.org/msa/collectors_corner/arc/moissanite.htm}}</ref> Yet the existence of moissanite in nature was questioned as late as 1986 by the American geologist Charles Milton.<ref>{{cite journal|journal = American Mineralogist|volume =79|pages = 190–192|date = 1994|title = Memorial of Charles Milton April 25, 1896 – October 1990|url=http://www.minsocam.org/ammin/AM79/AM79_190.pdf|author = Belkin, H. E. |author2=Dwornik, E. J. }}</ref> Discoveries show that it occurs naturally as inclusions in diamonds, [[xenolith]]s, and such other ultramafic rock such as [[lamproite]].<ref name="pierro">{{cite journal |author=Di Pierro S. |author2=Gnos E. |author3=Grobety B.H. |author4=Armbruster T. |author5=Bernasconi S.M. |author6=Ulmer P. |display-authors=4 |name-list-style=amp |date=2003 |title=Rock-forming moissanite (natural α-silicon carbide) |url=http://www.geoscienceworld.org/cgi/georef/2004018181 |journal=American Mineralogist |volume=88 |issue=11–12 |pages=1817–1821 |bibcode=2003AmMin..88.1817D |doi=10.2138/am-2003-11-1223 |s2cid=128600868}}</ref> ==Meteorites== Analysis of silicon carbide grains found in the [[Murchison meteorite]] has revealed anomalous [[isotopic ratio]]s of carbon and silicon, indicating an [[extraterrestrial materials|extraterrestrial origin]] from outside the [[Solar System]].<ref>Kelly, Jim. [http://img.chem.ucl.ac.uk/www/kelly/history.htm The Astrophysical Nature of Silicon Carbide]. chem.ucl.ac.uk</ref> 99% of these silicon carbide grains originate around carbon-rich [[asymptotic giant branch]] stars. Silicon carbide is commonly found around these stars, as deduced from their [[infrared spectra]].<ref>Greene, Dave. "[https://frugalrings.com/moissanite-vs-diamond-tester/ Will Moissanite Pass a Diamond Tester? | Best Test Options]". Retrieved 21 September 2019.</ref> The discovery of silicon carbide in the [[Canyon Diablo (meteorite)|Canyon Diablo meteorite]] and other places was delayed for a long time as [[carborundum|carborundum (SiC)]] contamination had occurred from man-made [[abrasive tool]]s.<ref name="pierro" /> == Physical properties == {{main article|Silicon carbide}} The crystalline structure is held together with strong [[covalent bonding]] similar to diamonds,<ref name = xu/> that allows moissanite to withstand high pressures up to 52.1 [[gigapascal]]s.<ref name = xu/><ref name = zhang>{{cite journal|author = Zhang J. |display-authors=4 |author2= Wang L. |author3=Weidner D.J. |author4=Uchida T. |author5=Xu J. |name-list-style=amp |date = 2002| title = The strength of moissanite |journal = American Mineralogist|volume = 87|issue=7 | pages = 1005–1008 |url = http://www.minsocam.org/msa/AmMin/toc/Abstracts/2002_Abstracts/July02_Abstracts/Zhang_p1005_02.pdf|bibcode=2002AmMin..87.1005Z|doi=10.2138/am-2002-0725|s2cid=35234290 }}</ref> Colors vary widely and are graded from D to K range on the [[Diamond color|diamond color grading scale]].<ref name = Read>{{cite book| author = Read P.|date = 2005| title = Gemmology |publisher = Elsevier Butterworth-Heinemann| place = Massachusetts|url = https://books.google.com/books?id=t-OQO3Wk-JsC| isbn = 978-0-7506-6449-3}}</ref> == Sources == All applications of silicon carbide today use [[Silicon carbide#Production|synthetic material]], as the natural material is very scarce. The idea that a silicon-carbon bond might in fact exist in nature was first proposed by the Swedish chemist [[Jöns Jacob Berzelius]] as early as 1824 (Berzelius 1824).<ref>{{Cite web |url=http://img.chem.ucl.ac.uk/www/kelly/history.htm |title = Silicon Carbide – Older than the Stars}}</ref> In 1891, [[Edward Goodrich Acheson]] produced viable minerals that could substitute for diamond as an abrasive and cutting material.<ref>{{Cite web|url=https://www.britannica.com/science/silicon-carbide|title = Silicon carbide &#124; chemical compound}}</ref> This was possible, as moissanite is one of the hardest substances known, with a hardness just below that of [[diamond]] and comparable with those of cubic [[boron nitride]] and [[boron]]. Pure synthetic moissanite can also be made from [[thermal decomposition]] of the preceramic polymer [[poly(methylsilyne)]], requiring no binding matrix, e.g., cobalt metal powder. Single-crystalline silicon carbide, in certain forms, has been used for the fabrication of high-performance semiconductor devices. As natural sources of silicon carbide are rare, and only certain atomic arrangements are useful for gemological applications, North Carolina–based [[Wolfspeed|Cree Research, Inc.]], founded in 1987, developed a commercial process for producing large single crystals of silicon carbide. Cree is the world leader in the growth of single crystal silicon carbide, mostly for electronics use.<ref>{{Cite web |url=https://www.moissanitejewelry.com/history.htm |title=Moissanite History}}</ref> In 1995 C3 Inc., a company helmed by Charles Eric Hunter, formed [[Charles & Colvard]] to market gem quality moissanite. Charles & Colvard was the first company to produce and sell synthetic moissanite under U.S. patent US5723391 A, first filed by C3 Inc. in North Carolina.<ref>{{Cite web |url=https://patents.google.com/patent/US5723391 |title=Silicon carbide gemstones}}</ref> == Applications == {{main article|Silicon carbide#Uses}} [[File:Moissanite_ring_natural_light.jpg|thumb|A moissanite engagement ring]] [[File:Moissanite Diamond - Emerald Cut.jpg|thumb|Moissanite: emerald cut]] Moissanite was introduced to the jewelry market as a [[diamond alternative]] in 1998 after [[Charles & Colvard]] (formerly known as C3 Inc.) received patents to create and market lab-grown silicon carbide gemstones, becoming the first firm to do so. By 2018 all patents on the original process world-wide had expired.<ref>{{cite patent |inventor1-last=Hunter |inventor1-first=Charles Eric |inventor2-last=Verbiest |inventor2-first=Dirk |fdate=1995-08-31 <!-- expired 2015-08-31 --> |status=patent |country-code=US |patent-number=5762896 |title=Single crystal gems hardness, refractive index, polishing, and crystallization}}</ref><ref>{{cite patent |inventor1-last=Hunter |inventor1-first= Charles Eric |inventor2-last=Verbiest |inventor2-first=Dirk |pridate=1995-08-31 <!-- expired 2015-08-31 --> |country-code=US |patent-number=5723391 |title=Silicon carbide gemstones |status=expired}}</ref><ref>{{cite web |title=Moissanite gem patent restrictions by country and year of expiration |url=http://betterthandiamond.com/pages/Moissanite-Gem-Patent-restrictions-by-country-and-year-of-expiration.html |website=Better than Diamond}}</ref> Charles & Colvard currently makes and distributes moissanite jewelry and loose gems under the trademarks ''Forever One'', ''Forever Brilliant'', and ''Forever Classic''.<ref>{{cite magazine | title= Moissanite Rights | date= May 1998 | magazine= Professional Jeweler Magazine | url= http://www.professionaljeweler.com/archives/articles/1998/may98/0598press1.html | access-date= 24 October 2012 | archive-date= 23 January 2023 | archive-url= https://web.archive.org/web/20230123083046/http://www.professionaljeweler.com/archives/articles/1998/may98/0598press1.html | url-status= dead }}</ref> Other manufacturers market silicon carbide gemstones under trademarked names such as ''Amora''. On the [[Mohs scale of mineral hardness]] (with diamond as the upper extreme, 10) moissanite is rated as 9.25.<ref name=Handbook/> As a diamond alternative Moissanite has some optical properties exceeding those of diamond. It is marketed as a lower price alternative to diamond that does not involve the expensive mining practices used for the extraction of natural diamonds. As some of its properties are quite similar to diamond, moissanite may be used as counterfeit diamond. Testing equipment based on measuring [[thermal conductivity]] in particular may give results similar to diamond. In contrast to diamond, moissanite exhibits a [[thermochromism]], such that heating it gradually will cause it to temporarily change color, starting at around {{convert|65|C|abbr=on|-1}}. A more practical test is a measurement of [[electrical conductivity]], which will show higher values for moissanite. Moissanite is [[birefringent]] (i.e., light sent through the material splits into separate beams that depend on the source polarization), which can be easily seen, and diamond is not.<ref>{{cite web |url= http://www.gemsociety.org/article/diamond-look-alike-comparison-chart/ |title=Diamond look-alike comparison chart |website= gemsociety.org| publisher= International Gem Society| date= | access-date= }}</ref> Because of its hardness, it can be used in high-pressure experiments, as a replacement for diamond (see [[diamond anvil cell]]).<ref name=xu/> Since large diamonds are usually too expensive to be used as anvils, moissanite is more often used in large-volume experiments. Synthetic moissanite is also interesting for [[electronics|electronic]] and thermal applications because its thermal conductivity is similar to that of diamonds.<ref name=zhang/> High power silicon carbide electronic devices are expected to find use in the design of protection circuits used for motors, [[actuator]]s, and energy storage or pulse power systems.<ref name=baliga>{{cite journal |last1=Bhatnagar |first1= M. |last2=Baliga |first2=B.J. |title=Comparison of 6H-SiC, 3C-SiC, and Si for power devices |journal=IEEE Transactions on Electron Devices |year=1993 |volume=40 |issue=3 |pages=645–655 |doi=10.1109/16.199372 |bibcode=1993ITED...40..645B}}</ref> It also exhibits [[thermoluminescence]],<ref>{{cite journal |last=Godfrey-Smith |first=D.I. |title=Applicability of moissanite, a monocrystalline form of silicon carbide,to retrospective and forensic dosimetry |journal=Radiation Measurements |date=Aug 1, 2006 |volume=41 |issue=7 |pages=976–981 |doi=10.1016/j.radmeas.2006.05.025 |bibcode=2006RadM...41..976G |url=https://www.deepdyve.com/lp/elsevier/applicability-of-moissanite-a-monocrystalline-form-of-silicon-carbide-Uaw0AcXWN0 |access-date=23 December 2017 |df=dmy-all |archive-date=26 July 2020 |archive-url=https://web.archive.org/web/20200726052506/https://www.deepdyve.com/lp/elsevier/applicability-of-moissanite-a-monocrystalline-form-of-silicon-carbide-Uaw0AcXWN0 |url-status=dead }}</ref> making it useful in radiation [[dosimetry]].<ref>{{cite journal |last1= Bruzzia |first1=M. |last2=Navab |first2=F. |last3=Piniac |first3=S. |last4=Russoc |first4=S. |title=High quality SiC applications in radiation dosimetry |journal=Applied Surface Science |date=12 December 2001 |volume=184 |issue=1–4 |pages=425–430 |doi=10.1016/S0169-4332(01)00528-1 |bibcode=2001ApSS..184..425B}}</ref> ==See also== *[[Charles & Colvard]] *[[Cubic zirconia]] *[[Diamond]] *[[Engagement ring]] *[[Fair trade]] *[[Glossary of meteoritics]] ==References== {{Reflist|30em}} == External links == * {{commons category-inline|Moissanite}} {{Meteorites}} [[Category:Carbide minerals]] [[Category:Hexagonal minerals]] [[Category:Minerals in space group 186]] [[Category:Meteorite minerals]] [[Category:Native element minerals]] [[Category:Gemstones]] [[Category:Green River Formation]]'