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Click on a
letter above to view the list of gems. |
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| Chemistry:
Na3AlF6 [Sodium
Aluminum
Fluoride] | Discovered
in 1799;
IMA
status: Valid (pre-IMA; Grandfathered). Cryollite
is named from the Greek
words, kryos meaning frost and lithos meaning
stone, hence ice-stone, in allusion to
its appearance. |
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Classification
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Mineral
Classification: |
Halides |
Strunz 8th
Ed. ID:
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3/B.03-30 |
Nickel-Strunz 10th
Ed. ID:
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3.CB.15 |
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3 : HALIDES C : Complex halides B : Neso-aluminofluorides
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Related
to: |
Kryolithionite-Calcjarlite
Series
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Crystal
Data
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Crystallography:
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Monoclinic
- Prismatic |
Crystal
Habit:
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Crystals
are pseudocubic or short prismatic, striated, to 3 cm;
also typically massive or coarsely granular.
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Twinning:
|
Common,
according to one or more of 13 distinct twin laws, producing
penetration, repeated, or polysynthetic twins.
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Physical
Properties
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Cleavage: |
None;
Parting on [001] and [110]
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Fracture: |
Irregular,
Uneven
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Tenacity:
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Brittle
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Moh's
Hardness: |
2.5
- 3.0
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Density:
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2.95 - 3.00 (g/cm3) |
Luminescence:
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Weakly
thermoluminescent; may fluoresce intense yellow under
SW UV, with yellow phosphorescence, pale yellow fluorescence
under LW UV. |
Radioactivity:
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Not
Radioactive
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Other: |
Slightly
soluble in water |
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Optical
Properties
|
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Color: |
Colorless, Gray, White, Reddish brown,
Brownish black |
Transparency: |
Transparent
to Translucent |
Luster: |
Vitreous,
Greasy, Pearly |
Refractive
Index: |
1.3385 - 1.340 Biaxial
( + ) |
Birefringence: |
0.0010 - 0.0011 |
Dispersion: |
None;
r < v
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Pleochroism: |
X
= colorless; Y = colorless; Z = colorless
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Occurances
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Geological
Setting: |
A
late-stage mineral in some granite pegmatites; in tin-bearing
alkalic granites; a vapor-phase mineral along fractures
and in the groundmass of some fluorine-rich, topaz-bearing
rhyolites; in pods in a carbonatite vein cutting fenitized
biotite gneiss. Also as a rare authigenic component
of the marlstones and shales of the Green River Formation. |
Common
Associations: |
Chiolite,
Feldspar Group, Fluorite, Pachnolite, Quartz, Topaz |
Type
Locality: |
Cryolite deposit, Ivittuut (Ivigtut), Arsuk Firth,
Arsuk, Kitaa Province (West Greenland), Greenland |
Year
Discovered: |
1799 |
View
mineral photos: |
Cryolite
Mineral Photos and Locations |
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More
Information
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|
Mindat.org Webmineral.com |
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Cryolite
is a very rare gem since gem quality crystals are very
rare and only available from one source. It is typically
colorless and usually has a slightly sleepy look. The
index of refraction of Cryolite is 1.3385, which is
very close to the index of refraction of water (1.3328).
The result is that if you put a clean, colorless gem
or crystal of Cryolite in water, it will essentially
disappear.
Sources
of Cryolite include the Ivigtut area of Greenland and also at the foot of Pikes Peak at Creede,
Colorado, USA, Mont Saint-Hilaire and Francon Quarry, Montreal, Quebec, Canada
and at Miask, Russia. Gem quality crystals are usually only from Francon
Quarry.
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Cryolite
gems for sale:
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Gem:
|
Cryolite |
Stock
#:
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CRYO-001 |
Weight:
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0.3350
ct |
Size: |
5.79
x 3.80 x 2.73 mm |
Shape: |
Pear |
Color: |
Colorless |
Clarity: |
Eye
Clean - SI |
Origin: |
Montreal,
Quebec, Canada |
Treatment: |
None
(natural) |
Price: |
SOLD
(but we have others) |
Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
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A
very rare gem from the Francon Quarry, Montreal, Quebec, Canada.
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