# Alluaudite

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> Source: https://en.wikipedia.org/wiki/Alluaudite
> Source revision: 1263588398
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{{Short description|Relatively common alkaline manganese iron phosphate mineral}}
{{Infobox mineral
| name        = Alluaudite
| image       = Alluaudite 2 Sodium iron manganese phosphate Pleasant Valley Mine near Fourmile Custer County South Dakota 2264Spp.jpg
| alt         = 
| caption     = Alluaudite
| category    = [Phosphate minerals](/source/Phosphate_minerals)
| formula     = {{chem2|(Na,Ca)Mn^{2+}(Fe^{3+},Mn^{2+},Fe^{2+},Mg)2(PO4)3}}
|IMAsymbol=Ald<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      = 8.AC.10
| dana        = 38.2.3.6
| system      = [Monoclinic](/source/Monoclinic)
| class       = Prismatic (2/m) <br/><small>(same [H-M symbol](/source/H-M_symbol))</small>
| symmetry    = ''C2/c''
| unit cell   = a = 11.03&nbsp;[Å](/source/angstrom), b = 12.53&nbsp;Å <br/>c = 6.4&nbsp;Å; β = 97.57°; Z&nbsp;=&nbsp;4
| color       = Dirty yellow to brownish yellow, grayish green; superficially dull greenish black, brownish black, black, when altered
| habit       = Platy to radiating fibrous, nodular, granular, massive 
| twinning    = Polysynthetic
| cleavage    = Distinct/ good on {100} and {010}, good on {110}
| fracture    = 
| tenacity    = 
| mohs        = 5 – 5.5
| luster      = 
| streak      = Brownish yellow
| diaphaneity = Translucent
| gravity     = 3.4 – 3.5
| density     = 
| polish      = 
| opticalprop = Biaxial (+)
| refractive  = n<sub>α</sub> = 1.782 n<sub>β</sub> = 1.802 n<sub>γ</sub> = 1.835
| birefringence = δ = 0.053
| pleochroism = X = pale olive-green, straw-yellow to greenish yellow; Z = pale olive-greenish to brownish yellow
| 2V          = Measured: 50° to 90°, calculated: 78°
| dispersion  = 
| extinction  = 
| length fast/slow =
| fluorescence = 
| absorption  = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| impurities  = 
| alteration  = 
| other       = 
| references  = <ref name=Mindat/><ref name=HBM/><ref>[http://www.webmineral.com/data/Alluaudite.shtml#.VTekNNK6fRY Alluaudite data on Webmineral]</ref>
}}

'''Alluaudite''' is a relatively common [alkaline](/source/alkaline) [manganese](/source/manganese) [iron](/source/iron) [phosphate mineral](/source/phosphate_mineral) with the chemical formula {{chem2|(Na,Ca)Mn^{2+}(Fe^{3+},Mn^{2+},Fe^{2+},Mg)2(PO4)3}}. It occurs as [metasomatic](/source/metasomatic) replacement in granitic [pegmatites](/source/pegmatites) and within phosphatic [nodules](/source/Nodule_(geology)) in [shale](/source/shale)s.<ref name=HBM/> 

It was first described in 1848 for an occurrence in [Skellefteå](/source/Skellefte%C3%A5), [Västerbotten](/source/V%C3%A4sterbotten), [Sweden](/source/Sweden).  It was named by [Alexis Damour](/source/Alexis_Damour) after [François Alluaud](/source/Fran%C3%A7ois_Alluaud) (II) (1778–1866).<ref name=Mindat>[http://www.mindat.org/min-142.html Alluaudite on Mindat.org]</ref><ref name=HBM>{{Cite web |url=http://www.handbookofmineralogy.org/pdfs/alluaudite.pdf |title=Alluaudite in the Handbook of Mineralogy |access-date=2009-12-21 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303205227/http://www.handbookofmineralogy.org/pdfs/alluaudite.pdf |url-status=dead }}</ref> The mineral structure was first described in 1955.<ref>{{Cite journal |last1=Nowagiel |first1=Maciej |last2=Samsel |first2=Mateusz J. |last3=Pietrzak |first3=Tomasz K. |date=2021-09-01 |title=Towards the High Phase Purity of Nanostructured Alluaudite-Type Glass-Ceramics Cathode Materials for Sodium Ion Batteries |journal=Materials |volume=14 |issue=17 |pages=4997 |doi=10.3390/ma14174997 |pmc=8434363 |pmid=34501086|bibcode=2021Mate...14.4997N |doi-access=free }}</ref>

==References==
{{Reflist}}

Category:Phosphate minerals
Category:Manganese(II) minerals
Category:Iron(II,III) minerals
Category:Sodium minerals
Category:Monoclinic minerals
Category:Minerals in space group 15
Category:Minerals described in 1848

{{phosphate-mineral-stub}}

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Adapted from the Wikipedia article [Alluaudite](https://en.wikipedia.org/wiki/Alluaudite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Alluaudite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.