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.
General Information |
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Chemical Formula | Na | | (Ca,Ce) | | (Fe,Mn,Y)ZrSi | | O | | (OH,Cl) | | | Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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Photos of natural/un-cut material from mindat.org |
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Physical Properties of Eudialyte |
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Mohs Hardness | 5 to 5.5Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Specific Gravity | 2.74 to 3.00Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Cleavage Quality | PoorArthur Thomas, Gemstones (2009) |
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Fracture | UnevenArthur Thomas, Gemstones (2009) |
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Optical Properties of Eudialyte |
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Refractive Index | 1.591 to 1.633Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Optical Character | Uniaxial/+Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Birefringence | 0.003 to 0.010Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Pleochroism | WeakArthur Thomas, Gemstones (2009) |
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Dispersion | NilArthur Thomas, Gemstones (2009) |
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Colour |
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Colour (General) | Brown-red, brown, pink.Walter Schumann, Gemstones of the world (2001) More from other references |
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Transparency | Translucent,OpaqueHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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Lustre | VitreousArthur Thomas, Gemstones (2009) |
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Crystallography of Eudialyte |
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Crystal System | TrigonalWalter Schumann, Gemstones of the world (2001) More from other references |
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Habit | Short rhombohedral to prismatic crystalsMichael O’Donoghue, Gems, Sixth Edition (2006) More from other references |
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Geological Environment |
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Where found: | Occurs in nepheline syenites, alkalic granites and associated pegmatitesMichael O’Donoghue, Gems, Sixth Edition (2006) |
Further Information |
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Mineral information: | Eudialyte information at mindat.org |
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Significant Gem Localities |
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| Canada | |
- Les Lacs-du-Témiscamingue
| Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 410 |
- La Vallée-du-Richelieu RCM
| Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 410 | | Russia | |
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