Sylvite

{{Short description|Potassium chloride mineral}} {{Infobox mineral | name = Sylvite | category = Halide mineral | boxwidth = | boxbgcolor = | image = Mineral Silvina GDFL105.jpg | imagesize = 250px | caption = | formula = KCl | IMAsymbol = Syl<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 = 74.55 g/mol | strunz = 3.AA.20 | system = Isometric | class = Hexoctahedral (m{{overline|3}}m) <br/>H-M symbol: (4/m {{overline|3}} 2/m) | symmetry = ''F''m3m | unit cell = a = 6.2931 Å; Z = 4 | color = Colorless to white, pale gray, pale blue; may be yellowish red to red due to hematite inclusions | habit = As cubes and octahedra; columnar, in crusts, coarse granular, massive | twinning = | cleavage = Perfect on [100], [010], [001] | fracture = Uneven | tenacity = Brittle to ductile | mohs = 2 | luster = Vitreous | polish = | refractive = 1.4903 | opticalprop = Isotropic | birefringence = | dispersion = | pleochroism = Visible in colored crystals | fluorescence= None | absorption = | streak = White | gravity = 1.993 | density = | melt = | fusibility = | diagnostic = | solubility = Soluble in water | diaphaneity = Transparent to translucent | other = Salty to bitter taste | references =<ref name=Mindat>[http://www.mindat.org/show.php?id=3850&ld=1&pho= Sylvite: Sylvite mineral information and data]</ref><ref>[http://webmineral.com/data/Sylvite.shtml Sylvite Mineral Data]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/sylvite.pdf Handbook of Mineralogy]</ref> }}

'''Sylvite''', or '''sylvine''', is potassium chloride (KCl) in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite (NaCl). The two are, in fact, isomorphous.<ref>Klein, Cornelis and Cornelius S. Hurlbut, Jr. 1993. ''Manual of Mineralogy after J.D. Dana, 21st edition''. New York: John Wiley & Sons, Inc.</ref> Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a specific gravity of 1.99. It has a refractive index of 1.4903.<ref>Deer, W.A., R.A. Howie, and J. Zussman. 1992. ''An Introduction to the Rock-Forming Minerals'' 2nd ed. New York: Prentice Hall.</ref> Sylvite has a salty taste with a distinct bitterness.

Sylvite is found in many evaporite deposits worldwide. Massive bedded deposits occur in New Mexico and western Texas, and in Utah in the US, but the largest world source is in Saskatchewan, Canada. The vast deposits in Saskatchewan were formed by the evaporation of a Devonian seaway. Sylvite is the official mineral of Saskatchewan.

Sylvite was first described in 1832 at Mount Vesuvius near Napoli in Italy and named after historical KCl designations ''sal degistivum Sylvii'' and ''sal febrifugum Sylvii'',<ref>{{Cite book |last=Watts |first=Henry |url=https://books.google.com/books?id=d-bkUHqUZ5AC&pg=PA147 |title=A Dictionary of Chemistry and the Allied Branches of Other Sciences |date=1883 |publisher=Longmans, Green, and Company |language=en}}</ref> which are named after the Dutch physician and chemist François Sylvius de le Boe (1614–1672).<ref name=Mindat/>

Sylvite, along with quartz, fluorite and halite, is used for spectroscopic prisms and lenses.<ref>{{cite journal|author=Motz, Lloyd|title=Spectroscopy|journal=Microsoft Encarta 2009|issue=2009|volume=S|page =1841}}</ref> {{clear|left}}

==See also== *{{annotated link|Sylvinite}}

==References== {{Reflist}}

==External links== *[https://web.archive.org/web/20110517165514/http://www.ir.gov.sk.ca/Default.aspx?DN=3563,3541,3538,3385,2936,Documents Mineral Resources of Saskatchewan] {{Cite EB1911|wstitle=Sylvite}} {{commons category|Sylvite}}

Category:Potassium minerals Category:Chloride minerals Category:Cubic minerals Category:Minerals in space group 225 Category:Evaporite Category:Potash Category:Rocksalt group