Mineral phase
IMA name
Eudialyte
Type
Class
silicate mineral
Compound type
cyclosilicate
Chemical composition
Formula
$Na^4(Ca,Ce)_2(Fe^{2+},Mn)Zr (Si_8O_{22})(OH,Cl)_2$
Chemical formula
Na4(Ca,Ce)2(Fe2+,Mn)ZrSi8O22(OH,Cl)2
Elemental formula
Na4 (Ca)1-2 (Ce)0-1 (Fe2+)0-1 (Mn2+)0-1 Zr Si8 (O)12-13 (H)1-2 (Cl)0-1
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Na$ Sodium element 4 constituent element main
$Ca$ Calcium element 1 - 2 constituent element main
$Ce$ Cerium element 0 - 1 constituent element main
$Fe^{2+}$ Iron(II) cation element 0 - 1 constituent element main
$Mn^{2+}$ Manganese(II) cation element 0 - 1 constituent element main
$Zr$ Zirconium element 1 constituent element main
$Si$ Silicon element 8 constituent element main
$O$ Oxygen element 12 - 13 constituent element main
$H$ Hydrogen element 1 - 2 constituent element main
$Cl$ Chlorine element 0 - 1 constituent element main
Composition comments
Common impurities: Y, K, Al, Ti
Chemical functions
  Function Number
$(SiO_4)^{4-}$
$(OH)^-$
Chemical bonds
  Bond Number
$\geq Si-O^-$ 4
$O^--H$ 1
Oxides
Formula $Na_{2}O$ $CaO$ $Ce_{2}O_{3}$ $Y_{2}O_{3}$ $ZrO_{2}$ $FeO$ $SiO_{2}$ $H_{2}O$
Mass fraction (%) 12.49 8.48 8.27 1.14 12.42 4.34 48.45 1.36
Oxides comments
From $Na_4Ca_{1.5}Ce_{0.5}Fe^{2+}_{0.6}Mn^{2+}_{0.3}Y_{0.1}ZrSi_8O_{22}(OH)_{1.5}Cl_{0.5}$

Strunz

Class
silicates (09)
Division
cyclosilicate (09.C)
Family
[Si9O27]18- 9-membered rings (09.CO)
Code
09.CO.10

Dana

Major class
silicates (VIII)
Class
cyclosilicates (64)
Type
Cyclosilicate Rings with Other Anions and Insular Silicate groups with mixed ring types (64.01)
Group
Eudialyte group (64.01.01)
Code
64.01.01.01
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
R-3m
Molar mass
992.15 $g/mol$
Density
2.74 - 3.1 $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
positive
Birefringence
0.003-0.004
Refraction index $n_o$ (w)
1.606-1.61
Refraction index $n_e$ (e)
1.61-1.613
Pure color
yellow
Color
Pinkish red, Red, Yellow, Yellowish brown, Violet
Diaphaneity
transparent to translucent
Luster
vitreous
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