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Cryptohalite

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Kladno, Central Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic
© Thomas Witzke

Show Cryptohalite Photos (2)
Formula:
(NH
 
4
)
 
2
[SiF
 
6
]
System:IsometricColour:Colourless, white, grey; ...
Lustre:VitreousHardness:2½
Name:From the Greek κρυπτός, concealed, and άλς, salt, in allusion to its intimate mixture with salammoniac in the type locality occurrence.
Dimorph of:Bararite
Isostructural with:Hieratite
This page provides mineralogical data about Cryptohalite.

Classification of Cryptohalite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:3/B.02-30
Nickel-Strunz 10th (pending) edition ID:3.CH.15

3 : HALIDES
C : Complex halides
H : Silicofluorides
Dana 8th edition ID:11.5.1.2

11 : HALIDE COMPLEXES
5 : AmBX6
Hey's CIM Ref.:8.12.5

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
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Physical Properties of Cryptohalite

Lustre:Vitreous
Colour:Colourless, white, grey; colourless in transmitted light
Hardness (Mohs):2½
Cleavage:Perfect
on {111}
Density (measured):2.004 g/cm3
Density (calculated):2.029 g/cm3

Crystallography of Cryptohalite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fm3m {F4/m 3 2/m}
Cell Parameters:a = 8.39Å
Unit Cell Volume:V 590.59 ų (Calculated from Unit Cell)
Morphology:Artificial crystals are cubo-octahedral and octahedral. Massive, as lumps with a mammillary surface or crusts; arborescent.

Optical Data of Cryptohalite

Type:Isotropic

Chemical Properties of Cryptohalite

Formula:
(NH
 
4
)
 
2
[SiF
 
6
]
Essential elements:F, H, N, Si
All elements listed in formula:F, H, N, Si

Relationship of Cryptohalite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
3.CH.05Malladrite
Na
 
2
[SiF
 
6
]
3.CH.10Bararite
(NH
 
4
)
 
2
[SiF
 
6
]
3.CH.15Hieratite
K
 
2
[SiF
 
6
]
3.CH.20Demartinite
K
 
2
[SiF
 
6
]
3.CH.25Knasibfite
K
 
3
Na
 
4
[SiF
 
6
]
 
3
[BF
 
4
]
Related Minerals - Hey's Index Grouping:

- +
8.12.1Ferruccite
Na[BF
 
4
]
8.12.2Avogadrite
(K,Cs)[BF
 
4
]
8.12.3Malladrite
Na
 
2
[SiF
 
6
]
8.12.4Hieratite
K
 
2
[SiF
 
6
]
8.12.6Bararite
(NH
 
4
)
 
2
[SiF
 
6
]

Other Names for Cryptohalite

Synonyms:
Criptoalite
Other Languages:
German:Kryptohalit
Russian:Криптогалит

Other Information

Other Information:Soluble in cold water, more so in hot water.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Cryptohalite

Reference List:Scacchi (1873) Reale accademia delle scienze fisische e matematiche, Naples, Att,: 6, no. 9 (as Criptoalite).

Topsøe (1874) Annales de chimie et de physique, Paris: 1: 22.

Gossner (1903) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 38: 147.

Bozorth (1922) American Chemical Society Journal: 44: 1066.

Christie (1926) Rec. Geol. Survey India: 59: 233.

Ketelaar (1935) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 92: 155.

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 104-105.

Journal of Chemical Physics: 44: 2499-2505.

Internet Links for Cryptohalite

Search Engines:
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    • External Links:
  • Look for Cryptohalite on Webmineral
  • Look for Cryptohalite on Athena Mineralogy
  • Look for Cryptohalite on Wikipedia
  • Look for Cryptohalite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Cryptohalite in the Natural History Museum (London) online catalogue
  • Cryptohalite details from Handbook of Mineralogy (PDF)
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    Localities for Cryptohalite

    Show Locality List (9 Items)
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 18th Nov 2009 04:45:01