{{Infobox mineral | name = Gaylussite | category = Carbonate mineral | image = Gaylussite-304155.jpg | imagesize = 260px | caption = | formula = Na<sub>2</sub>Ca(CO<sub>3</sub>)<sub>2</sub>·5H<sub>2</sub>O | IMAsymbol = Gyl<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 = 5.CB.35 | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''I2/a'' | color = Colorless, white, yellow, and grey | habit = Tabular prismatic crystals also granular | twinning = | cleavage = perfect [110] | fracture = Conchoidal, brittle | mohs = 2.5 | luster = vitreous | refractive = nα = 1.444 nβ = 1.516 nγ = 1.523 | opticalprop = Biaxial (−) | birefringence = δ = 0.079 | pleochroism = | streak = white | gravity = 1.93 – 1.99 | density = | melt = | fusibility = | diagnostic = | solubility = decomposes in water | diaphaneity = | other = efflorescent | references = <ref name=Handbook>[https://rruff.geo.arizona.edu/doclib/hom/gaylussite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-1662.html Mindat]</ref><ref name=Webmin>[https://webmineral.com/data/Gaylussite.shtml Webmineral]</ref> }}
'''Gaylussite''' is a carbonate mineral, a hydrated sodium calcium carbonate, formula Na<sub>2</sub>Ca(CO<sub>3</sub>)<sub>2</sub>·5H<sub>2</sub>O. It occurs as translucent, vitreous white to grey to yellow monoclinic prismatic crystals. It is an unstable mineral which dehydrates in dry air and decomposes in water.<ref name=Handbook/>
==Discovery and occurrence== It is formed as an evaporite from alkali lacustrine waters. It also occurs rarely as veinlets in alkalic igneous rocks.<ref name=Handbook/> It was first described in 1826 for an occurrence in Lagunillas, Mérida, Venezuela. It was named for French chemist Joseph Louis Gay-Lussac (1778–1850).<ref name=Mindat/>
The mineral has been recently (2014) reported from drill core in Lonar lake in Buldhana district, Maharashtra, India. Lonar lake was created by a meteor impact during the Pleistocene Epoch<ref>{{cite web|url=http://www.maharashtra.gov.in/pdf/gazeetter_reprint/Buldhana/gen_geology.html|title=Geology|work=Government of Maharashtra|publisher=Gazetteers Department|accessdate=2008-09-08}}</ref> and it is one of only four known hyper-velocity impact craters in basaltic rock anywhere on Earth.<ref name=ng>{{cite news|last1=Deshpande|first1=Rashmi|title=The Meteor Mystery Behind Lonar Lake|url=http://www.natgeotraveller.in/web-exclusive/web-exclusive-month/the-meteor-mystery-behind-lonar-lake/|accessdate=27 July 2015|agency=National Geographic Group|publisher=National Geographic Traveller Idia|date=3 December 2014|url-status=dead|archiveurl=https://web.archive.org/web/20150106061220/http://www.natgeotraveller.in/web-exclusive/web-exclusive-month/the-meteor-mystery-behind-lonar-lake/|archivedate=6 January 2015}}</ref><ref>Anoop et al., ''Palaeoenvironmental implications of evaporative gaylussite crystals from Lonar Lake, central India,'' Journal of Quaternary Science, V., Issue 4, pp. 349–359, May 2013</ref>
==References== {{Reflist}}
{{Commons category|Gaylussite}}
Category:Sodium minerals Category:Calcium minerals Category:Carbonate minerals Category:Pentahydrate minerals Category:Monoclinic minerals Category:Minerals in space group 15 Category:Evaporite Category:Luminescent minerals Category:Minerals described in 1826
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