Eudialyte
| Eudialyte | |
|---|---|
 | |
| General | |
| Category | Mineral |
| Formula (repeating unit) | Template:Sodium4(Template:CalciumTemplate:CeriumTemplate:IronTemplate:Manganese)2Template:ZirconiumTemplate:Silicon6Template:Oxygen17(Template:HydroxideTemplate:Chlorine)2 |
| Crystal system | Trigonal |
| Identification | |
| Color | Red, magenta, brown; also blue and yellow |
| Crystal habit | Granular, tabular |
| Cleavage | [0001] Imperfect |
| Fracture | Uneven |
| Mohs scale hardness | 5 - 5.5 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.8 - 3 |
| Refractive index | 1.598 - 1.602 |
| Pleochroism | Weak, brown-red to red-pink to yellow |
| Solubility | H2SO4 |
| Other characteristics |  Mildly Radioactive |
Eudialyte, whose name derives from the Greek eu and dialytos, meaning "welthruloosa", is a somewhat rare, red silicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites. Its name alludes to its ready solubility in acid.
Uses of eudialyte
Eudialyte is used as a minor ore of zirconium. Another use of eudialyte is as a minor gemstone, but this use is limited by its rarity, which is compounded by its poor crystal habit. These factors make eudialyte of primary interest as a collector's mineral.
Associated minerals
Eudialyte is found associated with other alkalic igneous minerals, in addition to the some minerals common to most igneous material in general. These minerals include:
- nepheline, (Template:Sodium, Template:Potassium)Template:AluminumTemplate:SiliconTemplate:Oxygen4
- aegirine, Template:SodiumTemplate:IronTemplate:Silicon2Template:Oxygen6
- natrolite, Template:Sodium2Template:Aluminum2Template:Silicon3Template:Oxygen10 · 2 H2O
- albite, Template:SodiumTemplate:AluminumTemplate:Silicon3Template:Oxygen8
Alternative names
Alternative names of eudialyte include: almandine spar and eudalite. Eucolite is the name of an altered form.
Notes for identification
Eudialyte's rarity makes locality useful in its identification. Prominent localities of eudialyte include Mont Saint-Hilaire in Canada and the Kola Peninsula in Russia, but it is also found in Greenland, Norway, and Arkansas. The lack of crystal habit, associated with color, is also useful for identification, as are associated minerals. A pink-red mineral with no good crystals associated with other alkaline igneous material, especially nepheline and aegirine, is a good indication a specimen is eudialyte.