{{Short description|Sulfate mineral}} {{Infobox mineral | name = Mendozite | category = Sulfate minerals, alum series | image = Mendozite.jpg | formula = NaAl(SO<sub>4</sub>)<sub>2</sub>·11H<sub>2</sub>O | IMAsymbol = Mz<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 = 440.26 g/mol | strunz = 7.CC.15 | dana = 29.5.4.1 | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''C2/c'' | color = colorless | habit = prismatic, pseudo-rhombohedral | cleavage = {100} good<br/>{001} indistinct<br/>{010} indistinct | mohs = 3 | luster = vitreous | streak = white | diaphaneity = transparent to translucent | density = 1.74 g/cm<sup>3</sup> | refractive = ''n''<sub>α</sub> = 1.449<br/>''n''<sub>β</sub> = 1.461<br/>''n''<sub>γ</sub> = 1.463 | opticalprop = biaxial (-) | birefringence = ''δ'' = 0.014 | 2V = 56° (measured) | solubility = soluble in water | alteration = tamarugite | references = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Mendozite Mineralienatlas]</ref><ref name="WebMineral">{{WebMineral | name = Mendozite | url = http://webmineral.com/data/Mendozite.shtml | accessdate = 2009-11-28}}.</ref><ref name="Mindat">{{Mindat | name = Mendozite | id = 2643 | accessdate = 2009-11-28}}.</ref><ref>{{citation | last1 = Fang | first1 = J. H. | last2 = Robinson | first2 = P. D. | year = 1972 | title = Crystal structures and mineral chemistry of double-salt hydrates: II. The crystal structure of mendozite, NaAl(SO<sub>4</sub>)<sub>2</sub>·11H<sub>2</sub>O | journal = American Mineralogist | volume = 57 | pages = 1081–88}}.</ref> }}
'''Mendozite''' is a sulfate mineral, one of the alum series, with formula NaAl(SO<sub>4</sub>)<sub>2</sub>·11H<sub>2</sub>O. It is a hydrated form of sodium aluminium sulfate (soda alum).
It was discovered in western Argentina in 1868, probably near San Juan. The exact location has been lost, but was described as "San Juan, near Mendoza", and it is the latter city that give the mineral its name.<ref name="WebMineral"/> It occurs in evaporites, presumably from the oxidation of sulfide minerals in the presence of clays.<ref name="WebMineral"/> It is very soluble in water, and so can only be found in dry regions: however, in can still effloresce (lose water of crystallisation) in extremely arid climates, altering to tamarugite (the hexahydrate).<ref name="Mindat"/>
==Bibliography== *<small>Palache, P.; Berman H.; Frondel, C. (1960). "''Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)"'' John Wiley and Sons, Inc., New York, pp. 469-471.</small>
==References== {{reflist}}
Category:Sodium minerals Category:Aluminium minerals Category:Sulfate minerals Category:Monoclinic minerals Category:Minerals in space group 15
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