Stishovite

<h2 id="appearance">Appearance</h2>
<p>Large natural crystals of stishovite are extremely rare and are usually found as clasts of 1 to 2 mm in length. When found, they can be difficult to distinguish from regular quartz without laboratory analysis. It has a vitreous luster, is transparent (or translucent), and is extremely hard. Stishovite usually sits as small rounded gravels in a matrix of other minerals.
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<h2 id="synthesis">Synthesis</h2>
<p>Until recently, the only known occurrences of stishovite in nature formed at the very high shock pressures (>100 kbar, or 10 GPa) and temperatures (> 1200 °C) present during <a href="/facts/Hypervelocity/5WqbktyA">hypervelocity</a> <a href="/facts/Meteorite/NsmHlBlX">meteorite</a> <a href="/facts/Impact_event/fbWu9Q4p">impact</a> into <a href="/facts/Quartz/4n86tE2G">quartz</a>-bearing <a href="/facts/Rock_(geology)/FXCJkmop">rock</a>.  Minute amounts of stishovite have been found within diamonds,<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> and post-stishovite phases were identified within ultra-high-pressure mantle rocks.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Stishovite may also be synthesized by duplicating these conditions in the laboratory, either isostatically or through shock (see <a href="/facts/Shocked_quartz/wUfFUvuH">shocked quartz</a>).<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
At 4.287 g/cm3, it is the second densest polymorph of silica, after <a href="/facts/Seifertite/SFAUQJoq">seifertite</a>. It has <a href="/facts/Tetragonal/12Aop255">tetragonal</a> crystal symmetry, P42/mnm, No. 136, <a href="/facts/Pearson_symbol/K3qljnNu">Pearson symbol</a> tP6.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a>
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Coesite/uQEYMrnD">Coesite</a>, a related mineral</li>
<li><a href="/facts/Thaumasite/T5lGfGvM">Thaumasite</a>, another rare mineral with hexacoordinated octahedral silica</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://web.archive.org/web/20040216002413/http://mineral.galleries.com/minerals/oxides/stishovi/stishovi.htm">Properties of stishovite</a></li>
<li><a href="http://www.umich.edu/~gs265/meteor.htm">Stishovite's origin in meteor impacts</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Dmitry L. Lakshtanov et al.  "The post-stishovite phase transition in hydrous alumina-bearing SiO2 in the lower mantle of the earth" PNAS 2007 104 (34) 13588-13590; doi:10.1073/pnas.0706113104. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Fleischer, Michael (1962). "New mineral names" (PDF). American Mineralogist. 47 (2). Mineralogical Society of America: 172–174. <a href="http://rruff.info/uploads/AM47_805.pdf" target="_blank">http://rruff.info/uploads/AM47_805.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Ross, Nancy L. (1990). "High pressure crystal chemistry of stishovite" (PDF). American Mineralogist. 75 (7). Mineralogical Society of America: 739–747. <a href="http://www.minsocam.org/ammin/AM75/AM75_739.pdf" target="_blank">http://www.minsocam.org/ammin/AM75/AM75_739.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Luo, Sheng-Nian; Swadener, J. G.; Ma, Chi; Tschauner, Oliver (2007). "Examining crystallographic orientation dependence of hardness of silica stishovite" (PDF). Physica B: Condensed Matter. 399 (2): 138. Bibcode:2007PhyB..399..138L. doi:10.1016/j.physb.2007.06.011. and references therein <a href="http://www.its.caltech.edu/~chima/publications/2007_PBCM_stishovite.pdf" target="_blank">http://www.its.caltech.edu/~chima/publications/2007_PBCM_stishovite.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>He, Duanwei; Zhao, Yusheng; Daemen, L.; Qian, J.; Shen, T. D.; Zerda, T. W. (2002). "Boron suboxide: As hard as cubic boron nitride". Applied Physics Letters. 81 (4): 643. Bibcode:2002ApPhL..81..643H. doi:10.1063/1.1494860. <a href="/wiki/Applied_Physics_Letters" target="_blank">/wiki/Applied_Physics_Letters</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>Fleischer, Michael (1962). "New mineral names" (PDF). American Mineralogist. 47 (2). Mineralogical Society of America: 172–174. <a href="http://rruff.info/uploads/AM47_805.pdf" target="_blank">http://rruff.info/uploads/AM47_805.pdf</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Wirth, R.; Vollmer, C.; Brenker, F.; Matsyuk, S.; Kaminsky, F. (2007). "Inclusions of nanocrystalline hydrous aluminium silicate "Phase Egg" in superdeep diamonds from Juina (Mato Grosso State, Brazil)". Earth and Planetary Science Letters. 259 (3–4): 384. Bibcode:2007E&PSL.259..384W. doi:10.1016/j.epsl.2007.04.041. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Liu, L.; Zhang, J.; Greenii, H.; Jin, Z.; Bozhilov, K. (2007). "Evidence of former stishovite in metamorphosed sediments, implying subduction to >350 km" (PDF). Earth and Planetary Science Letters. 263 (3–4): 180. Bibcode:2007E&PSL.263..180L. doi:10.1016/j.epsl.2007.08.010. Archived from the original (PDF) on 2010-07-17. <a href="https://web.archive.org/web/20100717031853/http://micron.ucr.edu/Public/KNB-papers/Liu-et-al-2007.pdf" target="_blank">https://web.archive.org/web/20100717031853/http://micron.ucr.edu/Public/KNB-papers/Liu-et-al-2007.pdf</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>J. M. Léger, J. Haines, M. Schmidt, J. P. Petitet, A. S. Pereira & J. A. H. da Jornada (1996). "Discovery of hardest known oxide". Nature. 383 (6599): 401. Bibcode:1996Natur.383..401L. doi:10.1038/383401a0.{{cite journal}}:  CS1 maint: multiple names: authors list (link) <a href="https://doi.org/10.1038%2F383401a0" target="_blank">https://doi.org/10.1038%2F383401a0</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>Smyth J. R.; Swope R. J.; Pawley A. R. (1995). "H in rutile-type compounds: II. Crystal chemistry of Al substitution in H-bearing stishovite" (PDF). American Mineralogist. 80 (5–6): 454–456. Bibcode:1995AmMin..80..454S. doi:10.2138/am-1995-5-605. S2CID 196903109. <a href="http://rruff.geo.arizona.edu/doclib/am/vol80/AM80_454.pdf" target="_blank">http://rruff.geo.arizona.edu/doclib/am/vol80/AM80_454.pdf</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
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Stishovite open-in-new

Stishovite