Eudialyte group

Eudialyte group is a group of complex trigonal zircono- and, more rarely, titanosilicate minerals with general formula [N(1)N(2)N(3)N(4)N(5)]3[M(1a)M(1b)]3M(2)3M(4)Z3[Si24O72]O'4X2, where N(1) and N(2) and N(3) and N(5) = Na+ and more rarely H3O+ or H2O, N(4) = Na+, Sr2+, Mn2+ and more rarely H3O+ or H2O or K+ or Ca2+ or REE3+ (rare earth elements), M(1) and M(1b) = Ca2+, M(1a) = Ca2+ or Mn2+ or Fe2+, M(2) = Fe (both II and III), Mn and rarely Na+, K+ or Zr4+, M(3) = Si, Nb and rarely W, Ti and [] (vacancy), M(4) = Si and or rarely [], Z Zr4+ and or rarely Ti4+, and X = OH−, Cl− and more rarely CO32− or F−. Some of the eudialyte-like structures can even be more complex, however, in general, its typical feature is the presence of [Si3O9]6− and [Si9O27]18− ring silicate groups. Space group is usually R3m or R-3m but may be reduced to R3 due to cation ordering. Like other zirconosilicates, the eudialyte group minerals possess alkaline ion-exchange properties, as microporous materials.

Approved species

 * Alluaivite - Na19(Ca,Mn)6(Ti,Nb)3Si26O74Cl*2H2O (space group R-3m)
 * Andrianovite - Na12(K,Sr,Ce)3Ca6Mn3Zr3NbSi(Si3O9)2(Si9O27)2O(O,H2O,OH)5 (space group R3m)
 * Aqualite – (H3O)8(Na,K,Sr)5Ca6Zr3Si26O66(OH)9Cl (space group R3)
 * Carbokentbrooksite – (Na,[ ])12(Na,Ce)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)*H2O (space group R3m)
 * Davinciite – Na12K3Ca6Fe3(2+)Zr3(Si26O73OH)Cl2 (space group R3m)
 * Dualite – Na30(Ca,Na,Ce,Sr)12(Na,Mn,Fe,Ti)6Zr3Ti3Mn(Si51O144)(OH,H2O,Cl)9 (space group R3m)
 * Eudialyte – Na15Ca6(Fe,Mn)3Zr3(Si3O9)2SiO(Si9O27)2(O,OH,H2O)3(OH,Cl)2 (space group R-3m)
 * Feklichevite – Na11Ca9(Fe(3+),Fe(2+))2Zr3Nb[Si25O73](OH,H2O,Cl,O)5 (space group R3m)
 * Fengchengite – Na12[ ]3(Ca,Sr)6Fe3(3+)Zr3Si(Si25O73)(H2O,OH)3(OH,Cl)2 (space group R-3m)
 * Ferrokentbrooksite – Na15Ca6(Fe,Mn)3Zr3NbSi25O73(O,OH,H2O)3(Cl,F,OH)2 (space group R3m)
 * Georgbarsanovite – Na12(Mn,Sr,REE)3Ca6Fe3Zr3NbSi25O76Cl2*H2O (space group R3m)
 * Golyshevite – (Na10Ca3)Ca6Zr3Fe2SiNb(Si3O9)2(Si9O27)2(OH)3(CO3)*H2O (space group R3m)
 * Ikranite – (Na,H3O)15(Ca,Mn)6Fe(3+)2Zr_{3–4}SiO(Si3O9)2(Si9O27)2*2\s 3H2O (space group R3m)
 * Ilyukhinite – (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2*3H2O – the most recent add (space group R3m)
 * Johnsenite-(Ce) – Na12(Ce,La,Sr,Ca)3Ca6Mn3Zr3WSiO(Si3O9)2(Si9O27)2(CO3)(OH,Cl)2*H2O (space group R3m)
 * Kentbrooksite – (Na,REE)15(Ca,REE)6(Mn,Fe)3Zr3(Si3O9)2SiO(Si9O27)2(O,OH,H2O)3F2*2H2O) (space group R3m)
 * Khomyakovite – Na12Sr3Ca6Fe3Zr3(W,Nb)SiO(Si3O9)2(Si9O27)2(O,OH,H2O)3(OH,Cl)2 (space group R3m)
 * Labyrinthite – (Na,K,Sr)35Ca12Fe3Zr6TiSi51O144(O,OH,H2O)9Cl3 (space group R3)
 * Manganokhomyakovite – Na12Sr3Ca6Mn3Zr3(W,Nb)SiO(Si3O9)2(Si9O27)2(O,OH,H2O)3(OH,Cl)2 (space group R3m)
 * Manganoeudialyte – Na14Ca6Mn3Zr3[Si26O72(OH)2]Cl2*4H2O (space group R3m)
 * Mogovidite – Na9(Ca,Na)5Ca6Zr3Fe2(SiNb)(Si3O9)2(Si9O27)2(CO3)(OH,H2O)3Cl0.3 (space group R3m)
 * Oneillite – Na15Ca3Mn3Fe(2+)3Zr3Nb(Si25O73)(O,OH,H2O)3(OH,Cl)2 (space group R3)
 * Raslakite – Na15Ca3Fe(2+)3(Na,Zr)3Zr3(Si,Nb)SiO(Si3O9)2(Si9O27)2(OH,H2O)3(Cl,OH) (space group R3)
 * Rastsvetaevite – Na27K8Ca12Fe3Zr6Si52O144(O,OH,H2O)6Cl2 (space group R3m)
 * Taseqite – Na12Sr3Ca6Fe3Zr3NbSiO(Si3O9)2(Si9O27)2(O,OH,H2O)3Cl2 (space group R3m)
 * Voronkovite – Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl*H2O (space group R3)
 * Zirsilite-(Ce) – (Na, [ ])12(Ce,Na)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)*H2O (space group R3m)

Unnamed species
The list of eudialyte-related natural phases is growing. There are many such phases, some of them very complex, coded "UM" by the International Mineralogical Association, and include:


 * UM-1971-22-SiO:CaClFeHMgMnNaNbZr – Na12Ca5(Ce,La,Y,Ca)Zr3(Zr,Nb)(Fe,Mn)3[Si9O_{24–26}(OH)_{1–3}]*2(Si3O9)2Cl – with variable substitution of OH for oxygen
 * UM1990-79-SiO:CaClFeHMnNaNbREEZr – Na14Ca5(Mg,Ca,Mn)Zr3(Si3O9)2(Si9O27)2(Si,Nb,Al,Zr)2(Fe,Zr)3(Mn,Na,Ce,La,Y)(Na,H2O,K,Sr)(OH)_{4–5}(OH,Cl) – first representative with magnesium-dominant site
 * UM1990-80- SiO:CaFeHMnNaNbREEZr – Na14Ca4(Mn,Ca)2Zr3(Si3O9)2(Si9O27)2(Si,Nb,Al,Zr)2(Fe,Mn,Al,Ti)3(Na,Ce,La,Y,Mn)(Na,H2O,K,Sr)(OH)_{7–8}
 * UM1998-21-SiO:CaCeClHMnNaZr – Na16Ca6(Mn,Ce)3Zr3(Si3O9)2(Si9O27)2(OH,Cl)4
 * UM1999-36-SiO:CaCeHMnNaNbSrZr – Na17Mn3Ca2Zr3Si26O72(OH,F,Cl)4
 * UM2000-66-SiO:CaClFeHMnNaNbSrZr – Na12(Ca,Mn)6(Sr,Na,K)3(Fe,Mn)3(Zr,Nb)4Si25O66(OH,Cl)11
 * UM2003-39- SiO:CaClFeHHfNaNbSrTaTiZr – Na12(Na,K,Mn,Sr)2Ca5(Ca,Mn)(Zr,Hf)3(Fe,[ ],Ta)3(Si,Nb,W)(Si,Al,Ti)Si24O72(OH,O)33.5Cl*1.2H2O
 * UM2004-51-SiO:CaClFFeHNaNbTi' – Na16Ca6(Fe,Mn)3Zr3(Ti,Nb)Si26O72FCl0.5*nH2O
 * UM2006-17-SiO:CaClFFeHMnNaZr – Na15(Ca3Mn3)Zr3(Fe,Zr)3SiSi(Si3O9)2(Si9O27)2O2(OH,F,Cl)3*2H2O
 * UM2006-18-SiO:CaClFFeHMnNaZr – Na15Ca3(Mn,Fe)3Zr3(Zr,Na)3(Si,Nb)(S,Ti,Si)(Si3O9)2(Si9O27)2(O,OH)5(Cl,F,H2O) – with essential sulfur and with Zr dominant in two sites
 * UM2006-28-SiO:CaHMnNaZr – Na33Ca12Zr6Mn3(Mn,Nb,Ti)2Si50O132(O,OH)12(OH,H2O,Cl)10 – with double c unit cell dimension

In addition, there is "eudialyte 3248": {{chem2|Na29Ca12Zr6[Si48O132(O,OH)12]{[Na]4[Si]2{[Mn]3[Mn,Nb,Ti]2}(OH,H2O,Cl)10}}, plus admixtures of Ce, Sr, Ba and Y, characterized by one S-dominant site (not shown in the simplified formula)

Other species
Rastsvetaeva et al. (2015) describe a species tentatively called "hydrorastsvetaevite", with a formula (Na11(H3O)11K6(H2O)_{1.5}Sr)Ca12Fe3Na2MnZr6Si52O144(OH)4.5Cl3.5.