{{Short description|Mineral}} {{infobox mineral | name = Serandite | category = Inosilicates | boxwidth = | boxbgcolor =#FA8072 | image = Serandite-Aegirine-20264.jpg | imagesize = 260px | caption = Serandite from Mont Saint-Hilaire, Quebec, Canada | formula = Na(Mn<sup>2+</sup>,Ca)<sub>2</sub>Si<sub>3</sub>O<sub>8</sub>(OH) | IMAsymbol = Srd<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 = 9.DG.05 | dana = 65.2.1.5 | system = Triclinic | class = Pinacoidal ({{overbar|1}}) <br/><small>(same H-M symbol)</small> | symmetry = ''P''{{overbar|1}} | unit cell = a = 7.683(1) Å, b = 6.889(1) Å <br/>c = 6.747(1) Å, α = 90.53(5)° <br/>β = 94.12(2)°, γ = 102.75(2)° <br/>Z = 2 | color = | habit = | twinning = Around [010] composition plane {100}, less commonly contact twin on {110} | cleavage = Perfect on {001} and {100} | fracture = Irregular, uneven | tenacity = Brittle | mohs = 5 to 5.5 | luster = Vitreous to greasy; fibrous aggregates are dull to silky<ref name=handbook>{{cite web |title=Sérandite |url=http://www.handbookofmineralogy.com/pdfs/serandite.pdf |work=Handbook of Mineralogy |publisher=Mineral Data Publishing |accessdate=July 11, 2012 |archive-date=September 11, 2021 |archive-url=https://web.archive.org/web/20210911014309/http://www.handbookofmineralogy.com/pdfs/serandite.pdf |url-status=dead }}</ref> | polish = | refractive = n<sub>α</sub> = 1.668<br>n<sub>β</sub> = 1.671<br>n<sub>γ</sub> = 1.703 | opticalprop = Biaxial (+) | birefringence = δ = 0.035 | 2V = 39° | dispersion = r < v moderate | pleochroism = | fluorescence= | absorption = | streak = White | gravity = | density = 3.34 g/cm<sup>3</sup> (measured) | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent, Translucent | other = | references =<ref name=mindat>{{cite web|title=Sérandite|url=http://www.mindat.org/min-3622.html|publisher=Mindat|accessdate=July 11, 2012}}</ref> |colour=salmon pink to orange}} '''Serandite'''<ref name=webmin>{{cite web|title=Serandite|url=http://www.webmineral.com/data/Serandite.shtml|publisher=Webmineral|accessdate=July 25, 2012}}</ref> is a mineral with formula Na(Mn<sup>2+</sup>,Ca)<sub>2</sub>Si<sub>3</sub>O<sub>8</sub>(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless.
==Description== Serandite is transparent to translucent and is normally salmon-pink, light pink, rose-red, orange, brown, black, or colorless; in thin section, it is colorless.<ref name=handbook/> Octahedrally bonded Mn(II) is the primary contributor to the mineral's pink colors.<ref name=M357>Manning, p. 357.</ref>
Crystals of the mineral can be prismatic to acicular and elongated along [010], bladed, blocky, or tabular and flattened on {100}, occur as a radiating aggregate, or have massive habit.<ref name=handbook/> Sérandite is a member of the wollastonite group and is the manganese analogue of pectolite.<ref name=mindat/> It is sometimes used as a gemstone.<ref>Gemstones of North America – Volume 3 – Page 417 John Sinkankas – 1959</ref>
==History== Serandite was discovered on Rouma Island, part of the Los Islands in Guinea.<ref name=mindat/> The mineral was described by À. Lacroix in the journal ''Comptes rendus hebdomadaires des séances de l'Académie des Sciences''.<ref name=L189>Lacroix, p. 189.</ref> He named it ''sérandite'' in honor of J.M. Sérand, a mineral collector who helped in the collection of the mineral.<ref name=mindat/>
==Occurrence and distribution== Serandite has been found in Australia, Brazil, Canada, Guinea, Italy, Japan, Namibia, Norway, Russia, South Africa, and the United States.<ref name=mindat/> The type material is held at the National Museum of Natural History in Washington, D.C.<ref name=handbook/>
At Mont Saint-Hilaire, Quebec, serandite occurs in sodalite xenoliths and pegmatites cutting syenites within an intrusive alkalic gabbro-syenite complex. In Point of Rocks, New Mexico, it occurs in vugs in phonolite. At the Tumannoe deposit in Russia, serandite occurs in a manganese rich deposit associated with volcanic rocks and terrigenous (non-marine) sediments which has been altered by contact metamorphism.<ref name=handbook/>
Serandite has been found in association with aegirine, analcime, arfvedsonite, astrophyllite, eudialyte, fluorite, leucophanite, mangan-neptunite, microcline, nepheline, sodalite, and villiaumite.<ref name=handbook/>
==References== {{Reflist}}
===Bibliography=== *{{cite journal|last=Lacroix|first=À.|title=Les pegmatites de la syénite sodalitique de l'île Rouma (archipel de Los, Guinée française). Description d'un nouveau minéral (sérandite) qu'elles renferment|journal=Comptes rendus hebdomadaires des séances de l'Académie des Sciences|date=January 26, 1931|volume=192|pages=189–194|url=http://rruff.info/uploads/CRH192_189.pdf|language=French}} *{{cite journal|last=Manning|first=P. G.|title=Absorption spectra of the manganese-bearing chain silicates pyroxmangite, rhodonite, bustamite and serandite|journal=The Canadian Mineralogist|date=June 1968|volume=9|issue=3|pages=348–357|url=http://rruff.info/uploads/CM9_348.pdf|publisher=Mineralogical Association of Canada}}
==Further reading== *{{cite journal|last1=Jacobsen|first1=Steven D.|last2=Smyth|first2=Joseph R.|last3=Swope|first3=R. Jeffrey|last4=Sheldon|first4=Robert I.|title=Two proton positions in the very strong hydrogen bond of serandite, NaMn<sub>2</sub>[Si<sub>3</sub>O<sub>8</sub>(OH)]|journal=American Mineralogist|date= May–June 2000|volume=85|issue=5 & 6|pages=745–752|doi=10.2138/am-2000-5-613|bibcode=2000AmMin..85..745J|s2cid=14785226|url=http://rruff.info/uploads/AM85_745.pdf}} *{{cite journal|last1=Takeuchi|first1=Yoshio|last2=Yasuhiro|first2=Kudoh|last3=Yamanaka|first3=Takamitsu|title=Crystal chemistry of the serandite-pectolite series and related minerals|journal=American Mineralogist|date= April 1976|volume=61|issue=3 & 4|pages=229–237|url=http://www.minsocam.org/ammin/AM61/AM61_229.pdf}}
==External links== {{commonscat-inline|Serandite}}
{{DEFAULTSORT:Serandite}} Category:Triclinic minerals Category:Sodium minerals Category:Manganese(II) minerals Category:Calcium minerals Category:Hydroxide minerals Category:Inosilicates Category:Gemstones Category:Minerals in space group 2