Eudialyte

Eudialyte is named from Greek "eu" - well and "dialytos" - dissolved, alluding to its easy solubility in acids.

Transparent to translucent red to reddish brown eudialyte can occur as crystals or masses. Well-formed crystals are very rare, but faceted stones are very popular because of their attractive colouring. Small bright red crystals come from Mt Saint Hilaire, Quebec, Canada.

The massive eudialyte makes attractive cabochons and spheres. This material is found in Kola Peninsula, Russia.

Eudialyte Gemstones by Size

This table shows distribution of Eudialyte gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.10 cts
Heaviest:0.13 cts
Average:0.11 cts
Total photos:2
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0.10ct to 0.10ct0.10ct to 0.11ct0.11ct to 0.11ct0.11ct to 0.11ct0.11ct to 0.12ct0.12ct to 0.12ct0.12ct to 0.12ct0.12ct to 0.12ct0.12ct to 0.13ct0.13ct to 0.13ct
General Information
Chemical Formula
Na
 
4
(Ca,Ce)
 
2
(Fe,Mn,Y)ZrSi
 
8
O
 
22
(OH,Cl)
 
2
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Eudialyte
Mohs Hardness5 to 5.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.74 to 3.00
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Cleavage QualityPoor
Arthur Thomas, Gemstones (2009)
FractureUneven
Arthur Thomas, Gemstones (2009)
Optical Properties of Eudialyte
Refractive Index1.591 to 1.633
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterUniaxial/+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.003 to 0.010
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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PleochroismWeak
Arthur Thomas, Gemstones (2009)
DispersionNil
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Brown-red, brown, pink.
Walter Schumann, Gemstones of the world (2001)
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TransparencyTranslucent,Opaque
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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LustreVitreous
Arthur Thomas, Gemstones (2009)
Crystallography of Eudialyte
Crystal SystemTrigonal
Walter Schumann, Gemstones of the world (2001)
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HabitShort rhombohedral to prismatic crystals
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Occurs in nepheline syenites, alkalic granites and associated pegmatites
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Eudialyte information at mindat.org
Significant Gem Localities
Canada
 
  • Québec
    • Abitibi-Témiscamingue
      • Témiscamingue RCM
        • Les Lacs-du-Témiscamingue
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 410
    • Montérégie
      • La Vallée-du-Richelieu RCM
        • Mont Saint-Hilaire
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 410
Russia
 
  • Murmansk Oblast
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