Mineralogy Database

Cryptohalite Mineral Data

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General Cryptohalite Information

Help on Chemical  Formula: Chemical Formula: (NH4)2SiF6
Help on Composition: Composition: Molecular Weight = 178.15 gm
   Silicon   15.76 %  Si   33.73 % SiO2
   Hydrogen   4.53 %  H      -   % Calc as (NH4)2O
   Nitrogen  15.72 %  N    29.23 % (NH4)2O
   Fluorine  63.98 %  F    63.98 % F
               -   %   F   -26.94 % -O=F2    
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: (NH4)2SiF6
Help on Environment: Environment: Volcanic sublimate. Dimorphous with bararite, the lower-temperature form.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1873
Help on Locality: Locality: Vesuvius, Campania, Italy. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named from the Greek for concealed and salt, for being admixed with sal ammoniac.
Help on Synonym: Synonym: ICSD 18033
  PDF 44-1484

Cryptohalite Image

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Comments: White to colorless crystals of cryptohalite. The red color is due to admixtured (amorphous ?) selenium.
Location: Kladno, Stredocesk├Ż Kraj, Bohemia, Czech Republic. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

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  Bararite   Cryptohalite

Comments: White crystalline bararite intermixed with cryptohalite colored yellow by selenium.
Location: Shamokin, Northumberland County, Pennsylvani, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Cryptohalite Crystallography

Help on Cell Dimensions: Cell Dimensions: a = 8.395, Z = 4; V = 591.65 Den(Calc)= 2.00
Help on Crystal System: Crystal System: Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: F m3m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 4.844(1), 2.422(0.45), 2.098(0.35),

Physical Properties of Cryptohalite

Help on Cleavage: Cleavage: {111} Perfect
Help on Color: Color: Colorless, Gray, White.
Help on Density: Density: 2.011
Help on Diaphaneity: Diaphaneity: Transparent
Help on Hardness: Hardness: 2.5 - Finger Nail
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Cryptohalite

Help on Optical Data: Optical Data: Isotropic, n=1.369.

Calculated Properties of Cryptohalite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.02 gm/cc
note: Specific Gravity of Cryptohalite =2.00 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.16
Boson Index = 0.84
Help on Photoelectric: Photoelectric: PECryptohalite = 0.97 barns/electron
U=PECryptohalite x rElectron Density= 1.96 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cryptohalite is Not Radioactive

Cryptohalite Classification

Help on  Dana Class: Dana Class: (11)Halide Complexes; Alumino-fluorides
  (11.05)where (A)m B (X)6
  (11.05.01)Dana Group Hieratite K2SiF6 F m3m 4/m 3 2/m Cryptohalite (NH4)2SiF6 F m3m 4/m 3 2/m
Help on  Strunz Class: Strunz Class: 03.CH.15 03 - HALIDES
  03.C - Complex Halides
  03.CH -
03.CH.15 Cryptohalite (NH4)2SiF6 F m3m 4/m 3 2/m
03.CH.15 Hieratite K2SiF6 F m3m 4/m 3 2/m

Other Cryptohalite Information

Help on References: References: NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Cryptohalite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Dana No: Strunz No: 03.CH.15





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