Eudialyte group
Eudialyte group is a group of complex trigonal zircono- and, more rarely, titanosilicate minerals with general formula 33M3MZ3O'4X2, where N and N' and N and N = Na+ and more rarely H3O+ or H2O, N = Na+, Sr2+, Mn2+ and more rarely H3O+ or H2O or K+ or Ca2+ or REE3+, M and M = Ca2+, M = Ca2+ or Mn2+ or Fe2+, M = Fe, Mn and rarely Na+, K+ or Zr4+, M = Si, Nb and rarely W, Ti and, M = 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 6− and 18− ring silicate groups. Space group is usually R''3m 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.
List of the eudialyte-group minerals
Approved species
- Alluaivite -
- Andrianovite -
- Aqualite –
- Carbokentbrooksite –
- Davinciite –
- Dualite –
- Eudialyte –
- Feklichevite –
- Fengchengite –
- Ferrokentbrooksite –
- Georgbarsanovite –
- Golyshevite –
- Ikranite –
- Ilyukhinite – – the most recent add
- Johnsenite-(Ce) –
- Kentbrooksite –
- Khomyakovite –
- Labyrinthite –
- Manganokhomyakovite –
- Manganoeudialyte –
- Mogovidite –
- Oneillite –
- Raslakite –
- Rastsvetaevite –
- Taseqite –
- Voronkovite –
- Zirsilite-(Ce) –
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 – – with variable substitution of OH for oxygen
- UM1990-79-SiO:CaClFeHMnNaNbREEZr – – first representative with magnesium-dominant site
- UM1990-80- SiO:CaFeHMnNaNbREEZr –
- UM1998-21-SiO:CaCeClHMnNaZr –
- UM1999-36-SiO:CaCeHMnNaNbSrZr –
- UM2000-66-SiO:CaClFeHMnNaNbSrZr –
- UM2003-39- SiO:CaClFeHHfNaNbSrTaTiZr –
- UM2004-51-SiO:CaClFFeHNaNbTi' –
- UM2006-17-SiO:CaClFFeHMnNaZr –
- UM2006-18-SiO:CaClFFeHMnNaZr – – with essential sulfur and with Zr dominant in two sites
- UM2006-28-SiO:CaHMnNaZr – – with double c unit cell dimension