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Eudialyte
Current inventory:  2 gems
 

Chemistry:  Na₄(Ca,Ce)₂(Fe++,Mn,Y)ZrSi₈O₂₂(OH,Cl)₂

Discovered in 1819;   IMA status: Valid (pre-IMA; Grandfathered).
The name Eudialyte is from the Greek words eu meaning well and dialytos meaning decomposable, referring to its easy solubility in acids.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/E.23-10

8 : Silicates
E : Cyclosilicates, triplet rings [Si3O9]6-
23 : Eudialyte - Alluaivite series

Crystal Data

Crystallography:

Trigonal - Hexagonal - Scalenohedral

Crystal Habit:

Crystals short rhombohedral to long prismatic up to 10 cm. More commonly as irregular masses and vein filings.

Physical Properties

Cleavage:

[0001] Imperfect

Fracture:

Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 5.5

Density:

2.74 - 3.10 (g/cm³)

Radioactivity:

Mild; GRapi = 7,287.91 (Gamma Ray American Petroleum Institute Units)

Optical Properties

Color:

Pinkish red, Red, Yellow, Yellowish brown, Violet.

Transparency:

Transparent to Translucent

Luster:

Vitreous to dull (greasy)

Refractive Index:

1.606 - 1.613  Uniaxial ( + or - )

Birefringence:

0.003 - 0.010

Dispersion:

n/a

Pleochroism:

Weak

Occurances

Geological Setting:

PIn nepheline syenites, alkalic granites, and associated pegmatites; may be a major constituent, of both magmatic and late-stage pneumatolytic origin.

Type Locality:

Kangerdluarssuq (Kangerdluarsuk) Firth, Ilimaussaq complex, Narsaq, Kitaa (West Greenland) Province, Greenland

Year Discovered:

1819

View mineral photos:

Eudialyte Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Eudialyte is a rare gem discovered in 1819 in the Kitaa Province of Greenland. It is very rarely found as crystals clean enough for faceting and faceted gems are always small and usually included. It is mostly available as cabochons and known for its beautiful colors of reds and pinks and often translucent. Major sources of Eudialyte material are the Kola Peninsula in Russia and in Canada at Mont Saint-Hilaire and the Kipawa Complex at Sheffield Lake, both in Quebec. Eudialyte is actually composed of many minerals: Sodium, Cerium, Iron, Manganese, Zirconium, Silicon, Hydrogen, and Chlorine. It often contains traces of Yttrium also. Eudialyte may be mildly radioactive as defined in 49 CFR 173.403 (greater than 70 Bq/gram) due to the presence of Cerium (Ce).
 

  
Eudialyte gems for sale: