Dualite

{{Short description|Mineral of the eudialyte group}}

{{Use dmy dates|date=January 2025}}

{{infobox mineral

| name = Dualite

| category = Silicate mineral, cyclosilicate

| image =

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| formula = {{chem|Na|30|(Ca|,Na|,Ce|,Sr)|12|(Na|,Mn|,Fe|,Ti)|6}}{{chem|Zr|3|Ti|3|Mn|Si|51|O|144|(OH|,H|2|O|,Cl)|9}}

| IMAsymbol = Dua{{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}}

| strunz = 9.CO.10

| dana = 64.1b.1.4

| system = Trigonal

| class = Ditrigonal pyramidal (3m)
H-M symbol: (3m)

| symmetry = R3m

| unit cell = a = 14.15, c = 60.72 [Å] (approximated); Z = 3

| color = Yellow

| colour =

| habit = Anhedral grains

| twinning =

| cleavage = None

| fracture = Conchoidal

| tenacity = Brittle

| mohs = 5

| luster = Vitreous

| streak = White

| diaphaneity = Transparent or translucent

| gravity =

| density = 2.84 (measured), 2.81 (calculated; approximated)

| polish =

| opticalprop = Uniaxial (+)

| refractive = nω = 1.61, nε = 1.61 (approximated)

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| pleochroism = None

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| fluorescence = No

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Dualite is a very rare and complex mineral of the eudialyte group, its complexity being expressed in its formula {{chem|Na|30|(Ca|,Na|,Ce|,Sr)|12|(Na|,Mn|,Fe|,Ti)|6}}{{chem|Zr|3|Ti|3|Mn|Si|51|O|144|(OH|,H|2|O|,Cl)|9}}.Mindat, Dualite, http://www.mindat.org/min-27578.htmlKhomyakov, A.P., Nechelyustov, G.N., and Rastsvetaeva, R.K., 2009: Dualite, Na₃₀(Ca,Na,Ce,Sr)₁₂(Na,Mn,Fe,Ti)₆Zr₃Ti₃MnSi₅₁O₁₄₄(OH,H₂O,Cl)₉, a new zircono-titanosilicate with a modular eudialyte-like structure from the Lovozero alkaline Pluton, Kola Peninsula, Russia. Geology of Ore Deposits 50(7), 574-582 The formula is simplified as it does not show the presence of cyclic silicate groups.

The name of the mineral comes from its dual nature: zircono- and titanosilicate at once. Dualite has two modules in its structure: alluaivite one and eudialyte one. After alluaivite and labyrinthite it stands for third representative of the eudialyte group with essential titanium.