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{{short description|Silicon carbide mineral}}
'''Moissanite''' is a trade name given to [[silicon carbide]] (chemical formula [[Silicon|Si]][[Carbon|C]]) for use in the gem business. As a [[gemstone]], silicon carbide is similar to [[diamond]] in several important ways: it is transparent and extremely hard (9 1/4 on the [[mohs scale of mineral hardness|Mohs scale]], compared to 10 for diamond), with an [[index of refraction]] between 2.65 and 2.69 (compared to 2.42 for diamond). SiC has a [[hexagon|hexagonal]] [[crystal|crystalline]] structure.
{{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''<sub>3</sub>mc
| 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 = ~9.5
| luster = Adamantine to metallic
| refractive = n<sub>ω</sub> = 2.654 n<sub>ε</sub> = 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, [[diamagnetic]]
| 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]].
Naturally occurring moissanite is extremely rare, as it is not formed naturally in any quantity within the Earth, and thus is found only in tiny quantities in certain types of meteorite and as microscopic traces in [[corundum]] deposits and [[kimberlite]]. Virtually all of the silicon carbide sold in the world, including moissanite gemstones, is [[synthetic]]. Natural moissanite was first found in [[1905]] as a small component of a [[meteorite]] in [[Arizona]] by Dr. [[Ferdinand Henri Moissan]], after whom the material is named in the gem market. Synthetic [[silicon carbide]] has been known since [[1892]], when it was first produced by [[Eugene G. Acheson]] in his newly invented [[resistance furnace]]. Acheson named the material [[carborundum]] by analogy to [[corundum]], another very hard substance (9 on the Mohs scale). Moissan's discovery of naturally occurring SiC was disputed at first due to the potential for contamination of his sample by silicon carbide saw blades that were already on the market at that time.


== Background ==
In 1998 C3, Inc. ([[Charles and Colvard]]), a subsidiary of [[Cree Research, Inc.]], introduced gem-quality synthetic [[silicon carbide]] onto the market under the name "moissanite," marketing it as a lower-cost alternative to diamond. For example, a 1 caret moissanite gem sells for about $600 (2005 USD), while a diamond of similar size and color typically runs for upwards of $4500. Touted as the best, most convincing diamond simulant to date, moissanite kicked up quite a stir: Journalists and programmes such as [[Nova (series)|Nova]] reported on the troubling ease of misidentification between moissanite and diamond, citing incidents of fraud.
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.
While some properties of moissanite are closer to diamond than those of [[cubic zirconia]], another synthetic diamond simulant, once its properties are known, moissanite is perhaps even easier to identify. Jewellers were at first fooled by moissanite's [[thermal conductivity]] which approximates that of diamond, rendering older thermal testers useless; what worked with cubic zirconia did not work with moissanite.


== Geological occurrence ==
Moissanite is much harder than cubic zirconia (9 1/4 vs. 8 1/2), lighter (SG 3.33 vs. 5.6), and much more resistant to heat. This results in a stone of higher lustre, sharper facets and extraordinary resilience: loose moissanites may be placed directly into ring moulds, the stones surviving unscathed from temperatures up to twice the 900°C melting point of 18k [[gold]].
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>
Despite its mechanical superiority, there are several factors preventing moissanite from dethroning cubic zirconia as queen of diamond simulants:


==Meteorites==
; Anisotropy : Unlike isometric diamond and cubic zirconia, the [[polytype]] of moissanite presently synthesized is [[hexagon]]al: being doubly refractive, the stones are easily detected with a [[polariscope]] or even by eye, the strong [[birefringence]] being seen as a doubling of the stone's back facets. Moissanite is usually cut with its [[optic axis]] perpendicular to the table of the stone in order to minimize this "drunk vision" effect, but even a slight tilt will betray the stone's true nature.
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" />
; Dispersion : Moissanite has a [[Dispersion (optics)|dispersive]] power nearly 2.5 times greater than diamond (0.104 vs. 0.044); this means the 'fire' of moissanite is viewed as excessive by some (yet more beautiful by others).

; Colour : To date all moissanites have been plagued by a muddy tinge, usually green or gray. Lacking the brilliant whiteness of cubic zirconia, most moissanites would grade within the I-K colour range of diamond. However, it should be noted at least two fancy varieties of moissanite have been produced: a blue not unlike natural blue diamonds, and a rich green somewhat resembling [[tsavorite]].
== Physical properties ==
; Cost : Due to its relatively expensive manufacturing process, and because C3, Inc. is its only supplier as of 2005, moissanite is much more expensive than cubic zirconia (though it remains substantially cheaper than diamond).
{{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==
==See also==
*[[Charles & Colvard]]
*[[Cubic zirconia]]
*[[Diamond]]
*[[Engagement ring]]
*[[Fair trade]]
*[[Glossary of meteoritics]]


==References==
*[[Diamond simulant]]
{{Reflist|30em}}


== External links ==
== External links ==
* {{commons category-inline|Moissanite}}


{{Meteorites}}
*[http://www.mindat.org/min-2743.html Mindat.org]
*[http://mineral.galleries.com/minerals/elements/moissani/moissani.htm Mineral galleries - moissanite info.]
*[http://webmineral.com/data/Moissanite.shtml Webmineral - moissanite info.]
*[http://www.Moissanite-Co.com Moissanite Information]


[[Category:Carbide minerals]]
[[Category:Hexagonal minerals]]
[[Category:Minerals in space group 186]]
[[Category:Meteorite minerals]]
[[Category:Native element minerals]]
[[Category:Gemstones]]
[[Category:Gemstones]]
[[Category:Synthetic minerals]]
[[Category:Green River Formation]]
[[Category:Superhard materials]]

[[fr:Moissanite]]

Latest revision as of 14:20, 22 December 2024

Moissanite
General
CategoryMineral species
Formula
(repeating unit)		SiC
IMA symbolMoi[1]
Strunz classification1.DA.05
Crystal system6H polytype, most common: hexagonal
Crystal class6H polytype: dihexagonal pyramidal (6mm)
H-M symbol: (6mm)
Space group6H polytype: P63mc
Identification
ColorColorless, green, yellow
Crystal habitGenerally found as inclusions in other minerals
Cleavage(0001) indistinct
FractureConchoidal – fractures developed in brittle materials characterized by smoothly curving surfaces, e.g., quartz
Mohs scale hardness~9.5
LusterAdamantine to metallic
StreakGreenish gray
DiaphaneityTransparent
Specific gravity3.218–3.22
Refractive indexnω = 2.654 nε = 2.967
Birefringence0.313 (6H form)
Dispersion0.104
Ultraviolet fluorescenceOrange-red
Melting point2730 °C (decomposes)
SolubilityNone
Other characteristicsNot radioactive, diamagnetic
References[2][3][4]

Moissanite (/ˈmɔɪsəˌnaɪt/)[5] is naturally occurring silicon carbide and its various crystalline 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.

Background

[edit]

The mineral moissanite was discovered by Henri Moissan while examining rock samples from a meteor crater located in Canyon Diablo, Arizona, in 1893. At first, he mistakenly identified the crystals as diamonds, but in 1904 he identified the crystals as silicon carbide.[6][7] Artificial silicon carbide had been synthesized in the lab by Edward G. Acheson in 1891, just two years before Moissan's discovery.[8]

The mineral form of silicon carbide was named in honor of Moissan later on in his life.

Geological occurrence

[edit]

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[9] had been encountered. Then, in 1958, moissanite was found in the upper mantle Green River Formation in Wyoming and, the following year, as inclusions in the ultramafic rock kimberlite from a diamond mine in Yakutia in the Russian Far East.[10] Yet the existence of moissanite in nature was questioned as late as 1986 by the American geologist Charles Milton.[11]

Discoveries show that it occurs naturally as inclusions in diamonds, xenoliths, and such other ultramafic rock such as lamproite.[12]

Meteorites

[edit]

Analysis of silicon carbide grains found in the Murchison meteorite has revealed anomalous isotopic ratios of carbon and silicon, indicating an extraterrestrial origin from outside the Solar System.[13] 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.[14] The discovery of silicon carbide in the Canyon Diablo meteorite and other places was delayed for a long time as carborundum (SiC) contamination had occurred from man-made abrasive tools.[12]

Physical properties

[edit]
Main article: Silicon carbide

The crystalline structure is held together with strong covalent bonding similar to diamonds,[6] that allows moissanite to withstand high pressures up to 52.1 gigapascals.[6][15] Colors vary widely and are graded from D to K range on the diamond color grading scale.[16]

Sources

[edit]

All applications of silicon carbide today use 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).[17] In 1891, Edward Goodrich Acheson produced viable minerals that could substitute for diamond as an abrasive and cutting material.[18] 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 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.[19]

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.[20]

Applications

[edit]
Main article: Silicon carbide § Uses
A moissanite engagement ring
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.[21][22][23] Charles & Colvard currently makes and distributes moissanite jewelry and loose gems under the trademarks Forever One, Forever Brilliant, and Forever Classic.[24] 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.[4] 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 65 °C (150 °F). 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.[25]

Because of its hardness, it can be used in high-pressure experiments, as a replacement for diamond (see diamond anvil cell).[6] 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 electronic and thermal applications because its thermal conductivity is similar to that of diamonds.[15] High power silicon carbide electronic devices are expected to find use in the design of protection circuits used for motors, actuators, and energy storage or pulse power systems.[26] It also exhibits thermoluminescence,[27] making it useful in radiation dosimetry.[28]

See also

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References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Moissanite. Webmineral
  3. ^ Moissanite. Mindat
  4. ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W. and Nichols, Monte C. (eds.) "Moissanite" Archived 2016-03-03 at the Wayback Machine. Handbook of Mineralogy. Mineralogical Society of America
  5. ^ "Moissanite". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  6. ^ a b c d Xu J. & Mao H. (2000). "Moissanite: A window for high-pressure experiments". Science. 290 (5492): 783–787. Bibcode:2000Sci...290..783X. doi:10.1126/science.290.5492.783. PMID 11052937.
  7. ^ Moissan, Henri (1904). "Nouvelles recherches sur la météorité de Cañon Diablo". Comptes rendus. 139: 773–786.
  8. ^ Smith, Kady. "History and Applications of Silicon Carbide". Moissanite & Co. Retrieved 2 February 2016.
  9. ^ Yokoyama, T.; Rai, V. K.; Alexander, C. M. O’D.; Lewis, R. S.; Carlson, R. W.; Shirey, S. B.; Thiemens, M. H.; Walker, R. J. (March 2007). "Nucleosynthetic Os Isotopic Anomalies in Carbonaceous Chondrites" (PDF). 38th Lunar and Planetary Science Conference (1338): 1151. Bibcode:2007LPI....38.1151Y.
  10. ^ Bauer, J.; Fiala, J.; Hřichová, R. (1963). "Natural α–Silicon Carbide". American Mineralogist. 48: 620–634.
  11. ^ Belkin, H. E.; Dwornik, E. J. (1994). "Memorial of Charles Milton April 25, 1896 – October 1990" (PDF). American Mineralogist. 79: 190–192.
  12. ^ a b Di Pierro S.; Gnos E.; Grobety B.H.; Armbruster T.; et al. (2003). "Rock-forming moissanite (natural α-silicon carbide)". American Mineralogist. 88 (11–12): 1817–1821. Bibcode:2003AmMin..88.1817D. doi:10.2138/am-2003-11-1223. S2CID 128600868.
  13. ^ Kelly, Jim. The Astrophysical Nature of Silicon Carbide. chem.ucl.ac.uk
  14. ^ Greene, Dave. "Will Moissanite Pass a Diamond Tester? | Best Test Options". Retrieved 21 September 2019.
  15. ^ a b Zhang J.; Wang L.; Weidner D.J.; Uchida T.; et al. (2002). "The strength of moissanite" (PDF). American Mineralogist. 87 (7): 1005–1008. Bibcode:2002AmMin..87.1005Z. doi:10.2138/am-2002-0725. S2CID 35234290.
  16. ^ Read P. (2005). Gemmology. Massachusetts: Elsevier Butterworth-Heinemann. ISBN 978-0-7506-6449-3.
  17. ^ "Silicon Carbide – Older than the Stars".
  18. ^ "Silicon carbide | chemical compound".
  19. ^ "Moissanite History".
  20. ^ "Silicon carbide gemstones".
  21. ^ US patent 5762896, Hunter, Charles Eric & Verbiest, Dirk, "Single crystal gems hardness, refractive index, polishing, and crystallization" 
  22. ^ US expired 5723391, Hunter, Charles Eric & Verbiest, Dirk, "Silicon carbide gemstones" 
  23. ^ "Moissanite gem patent restrictions by country and year of expiration". Better than Diamond.
  24. ^ "Moissanite Rights". Professional Jeweler Magazine. May 1998. Archived from the original on 23 January 2023. Retrieved 24 October 2012.
  25. ^ "Diamond look-alike comparison chart". gemsociety.org. International Gem Society.
  26. ^ Bhatnagar, M.; Baliga, B.J. (1993). "Comparison of 6H-SiC, 3C-SiC, and Si for power devices". IEEE Transactions on Electron Devices. 40 (3): 645–655. Bibcode:1993ITED...40..645B. doi:10.1109/16.199372.
  27. ^ Godfrey-Smith, D.I. (1 August 2006). "Applicability of moissanite, a monocrystalline form of silicon carbide, to retrospective and forensic dosimetry". Radiation Measurements. 41 (7): 976–981. Bibcode:2006RadM...41..976G. doi:10.1016/j.radmeas.2006.05.025. Archived from the original on 26 July 2020. Retrieved 23 December 2017.
  28. ^ Bruzzia, M.; Navab, F.; Piniac, S.; Russoc, S. (12 December 2001). "High quality SiC applications in radiation dosimetry". Applied Surface Science. 184 (1–4): 425–430. Bibcode:2001ApSS..184..425B. doi:10.1016/S0169-4332(01)00528-1.
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