Stishovite

Infobox mineral
name = Stishovite
category = Mineral
boxwidth =
boxbgcolor =


imagesize =
caption =
formula = Silica (silicon dioxide, SiO2)
molweight =
color = Clear (if no impurities); also see Varieties
habit =
system =
twinning =
cleavage =
fracture =
mohs = 9.4
luster =
refractive = nω = 1.81
opticalprop =
birefringence =
pleochroism =
streak =
gravity = 4.28 when pure
density =
melt = 1650 (±75) °C
fusibility =
diagnostic =
solubility = 11.0 +/- 1.1 PPM @ 25 C
diaphaneity = Transparent to translucent
other =

Stishovite (after S.M. Stishov, 20th-century Russian mineralogist) is an extremely hard, dense tetragonal form (polymorph) of silicon dioxide. It was traditionally considered the hardest known oxide; however, boron suboxide was recently discovered to be much harder. At normal temperature and pressure, stishovite is metastable; it will eventually decay to quartz; however, this phase change is slow enough that it has never been observed. Stishovite was first discovered in nature and named by Edward C. T. Chao.

ynthesis

The only known occurrences of stishovite in nature formed at the very high shock pressures (>100 kbar = 10 GPa) and temperatures (> 1200°C) present during hypervelocity meteorite impact into quartz-bearing rock. Stishovite may also be synthesized by duplicating these conditions in the laboratory, either isostatically or through shock (see shocked quartz).

ee also

*Coesite, a related mineral

References

[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TX4-41YG719-D&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=5fe822b289eeed2f2e0e1bff9871860b High-pressure silica polymorphs as hardest known oxides]

External links

* [http://mineral.galleries.com/minerals/oxides/stishovi/stishovi.htm Properties of stishovite]
* [http://www.umich.edu/~gs265/meteor.htm Stishovite's origin in meteor impacts]


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Look at other dictionaries:

  • Stishovite — Catégorie IX : silicates[1] Général Numéro CAS …   Wikipédia en Français

  • stishovite — [stish′ə vīt΄] n. [after S. Stishov, Soviet mineralogist who discovered it + ITE1] a very dense, tetragonal form of silica that is colorless and transparent …   English World dictionary

  • stishovite — /stish euh vuyt /, n. Mineral. a rare polymorph of quartz, SiO2, formed under very high pressure, as by meteorite impact. Cf. coesite. [1960 65; named after S. M. Stishov, 20th century Russian mineralogist; see ITE1] * * * ▪ mineral       high… …   Universalium

  • stishovite — stišovitas statusas T sritis chemija apibrėžtis Didelio tankio, rutilui būdingos struktūros kvarco atmaina, mineralas. atitikmenys: angl. stishovite rus. стишовит …   Chemijos terminų aiškinamasis žodynas

  • stishovite — noun A fine grained mineral, SiO, that is a polymorphic form of quartz formed under very high pressure. Syn: stipoverite …   Wiktionary

  • stishovite — [ stɪʃəvʌɪt] noun a dense form of silica produced by very high pressures, e.g. in meteorite craters. Origin 1960s: from the name of the Russian chemist Sergei M. Stishov + ite1 …   English new terms dictionary

  • stishovite — stish·ov·ite …   English syllables

  • stishovite — ˈstishəˌvīt noun ( s) Etymology: Sergeĭ M. Stishov, 20th century Russ. mineralogist + English ite : a dense tetragonal mineral SiO2 consisting of silicon dioxide that is a polymorph of quartz and that is formed under great pressure …   Useful english dictionary

  • 13778-37-5 — Stishovite Stishovite Catégorie III : oxydes et hydroxydes Formule brute SiO2 Identification Classe cristalline et groupe d espace ditetragonal dipyramidal …   Wikipédia en Français

  • silica mineral — Any of the forms of silicon dioxide (SiO2), including quartz, tridymite, cristobalite, coesite, stishovite, melanophlogite, lechatelierite, and chalcedony. Various kinds of silica minerals have been produced synthetically. * * * Introduction… …   Universalium

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