Eudialyte group is a group of complex
trigonal
In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal ...
zircono- and, more rarely, titanosilicate
minerals
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed ...
with general formula
(1)N(2)N(3)N(4)N(5)sub>3
(1a)M(1b)sub>3M(2)
3M(4)Z
3 24O72">i24O72'
4X
2, where N(1) and N(2) and N(3) and N(5) =
Na+ and more rarely
H3O+ or
H2O, N(4) = Na
+, Sr
2+, Mn
2+ and more rarely H
3O
+ or H
2O or
K+ or Ca
2+ or REE
3+ (
rare earth elements
The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous sil ...
), M(1) and M(1b) = Ca
2+, 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 defect, vacancy), M(4) = Si and or rarely [], Z Zr
4+ and or rarely Ti
4+, and X = OH
−, Cl
− and more rarely CO
32− or F
−. Some of the eudialyte-like structures can even be more complex, however, in general, its typical feature is the presence of
3O9">i3O9sup>6− and
9O27">i9O27sup>18− ring silicate groups.
Space group
In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...
is usually ''R''3''m'' or ''R''-3''m'' but may be reduced to ''R''3 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 - (space group ''R''-3''m'')
*
Andrianovite - (space group ''R''3''m'')
*
Aqualite - (space group ''R''3)
*
Carbokentbrooksite - (space group ''R''3''m'')
*
Davinciite - (space group ''R''3''m'')
*
Dualite - (space group ''R''3''m'')
*
Eudialyte
Eudialyte, whose name derives from the Greek phrase , , meaning "well decomposable", is a somewhat rare, nine member ring cyclosilicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites. Its name alludes to its ready ...
- (space group ''R''-3''m'')
*
Feklichevite - (space group ''R''3''m'')
*
Fengchengite - (space group ''R''-3''m'')
*
Ferrokentbrooksite - (space group ''R''3''m'')
*
Georgbarsanovite - (space group ''R''3''m'')
*
Golyshevite - (space group ''R''3''m'')
*
Ikranite - (space group ''R''3''m'')
*
Ilyukhinite - - the most recent add (space group ''R''3''m'')
*
Johnsenite-(Ce) - (space group ''R''3''m'')
*
Kentbrooksite - (space group ''R''3''m'')
*
Khomyakovite - (space group ''R''3''m'')
*
Labyrinthite - (space group ''R''3)
*
Manganokhomyakovite - (space group ''R''3''m'')
*
Manganoeudialyte - (space group ''R''3''m'')
*
Mogovidite - (space group ''R''3''m'')
*
Oneillite - (space group ''R''3)
*
Raslakite - (space group ''R''3)
*
Rastsvetaevite - (space group ''R''3''m'')
*
Taseqite - (space group ''R''3''m'')
*
Voronkovite - (space group ''R''3)
*
Zirsilite-(Ce) - (space group ''R''3''m'')
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
In addition, there is "eudialyte 3248": , 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 .
Further reading
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*Rastsvetaeva, R. K.; Chukanov, N. V.; Zaitsev, V. A.; Aksenov, S. M.; Viktorova, K. A. (2018-05).
Crystal Structure of Cl-Deficient Analogue of Taseqite from Odikhincha Massif. ''Crystallography Reports''. 63 (3): 349–357.
doi:10.1134/s1063774518030240.
ISSN
An International Standard Serial Number (ISSN) is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs ...
1063-7745
*
References
{{Reflist
External links
Mindat.org
Cyclosilicates
Zirconium minerals
Sodium minerals