{{short description|Manganese phosphate mineral}} {{Infobox mineral |boxbgcolor=#d0a280| name = Hureaulite | category = Phosphate minerals | image = hureaulite 01.jpg | imagesize = 260px | caption = Hureaulite from the Cigana Claim, Conselheiro Pena, Minas Gerais, Brazil. Specimen size 2.8 cm. | formula = {{chem2|Mn(2+)5(PO3OH)2(PO4)2*4H2O}} | IMAsymbol = Hur<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 = 728.65 g/mol | strunz = 8.CB.10 (10 ed) <br/><small>7/C.04-10 (8 ed)</small> | dana = 39.2.1.1 | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''C2/c'' | unit cell = a = 17.594(10)&nbsp;Å <br/>b = 9.086(5)&nbsp;Å <br/>c = 9.404(5)&nbsp;Å <br/>β = 96.67(8)°; Z&nbsp;=&nbsp;4 | colour = Orange, red, yellow, brown, grey or nearly colourless | habit = Crystals are short prismatic parallel to (100) or equant, sometimes thick tabular, also massive or imperfectly fibrous<ref name = AM27>Murdoch, Joseph (1942) Contributions to the Crystallography of Hureaulite. American Mineralogist 27: 228</ref> | twinning = | cleavage = {100} good | fracture = Uneven | tenacity = Brittle | mohs = 3.5 | lustre = Vitreous to greasy | refractive = n<sub>α</sub> = 1.640 – 1.654 n<sub>β</sub> = 1.649 – 1.659 n<sub>γ</sub> = 1.655 – 1.662 | opticalprop = Biaxial (−) | 2V = greater than 60° | dispersion = r<v, very strong<ref name = Dana/> | birefringence = δ = 0.012 | pleochroism = X colourless, Y yellow to pale rose, Z reddish yellow to reddish brown | streak = Nearly white | gravity = 3.18–3.2 (measured), 3.23 (calculated) | density = | melt = | fusibility = | diagnostic = | solubility = Easily soluble in acids. | diaphaneity = Transparent to translucent | other = | references = <ref name = Dana>Gaines et al (1997) Dana's New Mineralogy Eighth Edition</ref><ref name=Mindat>http://www.mindat.org/min-1952.html Mindat.org</ref><ref name = AM70>Shigley and Brown (1985) American Mineralogist 70:395</ref><ref name = RCR>Roberts, Campbell and Rapp (1990) Encyclopedia of Minerals, 2nd edition</ref>}} '''Hureaulite''' is a manganese phosphate with the formula {{chem2|Mn(2+)5(PO3OH)2(PO4)2*4H2O}}. It was discovered in 1825 and named in 1826 for the type locality, Les Hureaux, Saint-Sylvestre, Haute-Vienne, Limousin, France. It is sometimes written as huréaulite, but the IMA does not recommend this for English language text.<ref name = MinRec39>Burke, E. A. J. (2008): Tidying up Mineral Names: An IMA scheme for Suffixes, Hyphens and Diacritical Marks. Mineralogical Record, 39, 134</ref>

A complete series exists from lithiophilite, {{chem2|LiMn(2+)PO4}} to triphylite, {{chem2|LiFe(2+)PO4}}, including hureaulite, strengite, {{chem2|FePO4*2H2O}}, stewartite, {{chem2|Mn(2+)Fe(3+)2(OH,PO4)2*8H2O}}, and sicklerite, {{chem2|(LiMn(2+),Fe(3+))PO4}}.<ref name = AM28>Murdoch, Joseph (1943) Crystallography of Hureaulite. American Mineralogist 28: 19-24</ref>

==Environment== Hureaulite is a secondary mineral occurring in granite pegmatites.<ref name = RCR/> At the type locality it occurs in a zone of altered triphylite, {{chem2|LiMn(2+)PO4}}, in pegmatite. Typically occurs very late in the sequence of formation of secondary phosphate minerals.<ref name = AM58>Moore, P B, and Araki, T (1973) Hureaulite: its atomic arrangement. American Mineralogist 58: 302-307.</ref> Associated at the type locality with vivianite, {{chem2|Fe(2+)3(PO4)2*8H2O}}; rockbridgeite, {{chem2|Fe(2+)Fe(3+)4(PO4)3(OH)5}}; heterosite, {{chem2|(Fe(3+),Mn(3+))PO4}} and cacoxenite, {{chem2|Fe(3+)24AlO6(PO4)17(OH)12*17H2O}}. It can be synthesised;<ref name = AC43>Gerault, Y, Riou, A, and Cudennec, Y (1987) Acta Crystallographica (C) 43:1829</ref> most natural hureaulites are Mn-rich compounds but extensive ({{chem2|Mn,Fe}}) solution is known for synthetic material.<ref name = AM58/>

==Localities== The type locality is Les Hureaux, Saint-Sylvestre, Haute-Vienne, Limousin, France. Hureaulite is also found in a granite pegmatite known for its phosphates in the Aimorés pegmatite district, at the Cigana claim in Galiléia, Doce valley, Minas Gerais, Brazil, formerly known as the Jocão Mine.<ref name=Mindat/>

==References== {{Reflist}} {{Commons}}

Category:Manganese(II) minerals Category:Phosphate minerals Category:Monoclinic minerals Category:Tetrahydrate minerals Category:Minerals in space group 15