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| Chemistry:
Na8Al6Si6O24Cl2 | Discovered
in 1811 ;
IMA
status: Valid (pre-IMA; Grandfathered). Sodalite
is named after its chemical composition containing Sodium
(Na). |
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Classification
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Mineral
Classification: |
Silicates |
Strunz 8th
Ed. ID:
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8/J.11-10 |
Nickel-Strunz 10th
Ed. ID:
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9.AC.05 |
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9 : SILICATES (Germanates) F : Tektosilicates without zeolitic
H2O B : Tektosilicates with additional anions (Sodalite
group)
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Crystal
Data
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Crystallography:
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Isometric
- Hextetrahedral |
Crystal
Habit:
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Crystals
rare, typically dodecahedra, to 10 cm; as embedded grains
or massive.
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Twinning:
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Common,
forming pseudohexagonal prisms.
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Physical
Properties
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Cleavage: |
[110]
Poor
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Fracture: |
Conchoidal
to Uneven, Irregular
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Tenacity:
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Brittle
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Hardness
(Mohs): |
5.5
- 6.0 |
Density:
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2.27
- 2.33 (g/cm3) |
Luminescence:
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Bright red-orange under SW and LW UV. cathodeluminescent. Yellowish
phosphorescence, may be photochromic in magentas. |
Radioactivity:
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Not
Radioactive |
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Optical
Properties
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Color: |
Colorless,
White, Yellowish, Greenish, Gray, light to dark Blue,
Azure Blue, Pink |
Transparency: |
Transparent
to Translucent |
Luster: |
Vitreous,
Greasy |
Refractive
Index: |
1.483
- 1.487 Isotropic |
Birefringence: |
0.00
(Isotropic) |
Dispersion: |
0.018 |
Pleochroism: |
None
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Occurances
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Geological
Setting: |
Found in nepheline syenites, phonolites, volcanic ejecta, metasomatized
calcareous rocks. |
Type
Locality: |
Ilimaussaq complex, Narsaq, Kitaa (West Greenland)
Province, Greenland |
Year
Discovered: |
1811 |
View
mineral photos: |
Sodolite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com |
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Sodalite is a member of the Sodalite
mineral group that also includes Hackmanite,
Tugtupite
and Lazurite. The
Sodalite mineral group is named after its most common
member. Sodalite
is also one of
the members of the Feldspathoid
group of minerals that includes Cancrinite,
Haüyne,
Lazurite, Leucite,
Nepheline and Sodalite. Minerals with chemistries that are close to
those of the alkalai Feldspars, but are poor in silica
(SiO2)
content, are called Feldspathoids. Sodalite is mostly known for vivid blue,
opaque material that is seldom transparent and clean
enough for faceting. Faceted gems are very rare
and usually very small.
Although
Sodalite is found in several localities around the world,
few of these produce transparent crystals for faceting.
A recent find in Afghanistan has produced some beautiful,
colorless, very clean gems. Other locations such as
Bancroft, Ontario, Canada are the source of small, semi-transparent,
vivid blue gems.
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Soldalite
gems for sale:
We
have not photographed our Sodalite gems yet. Please
check back soon!
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