Cryptohalite Mineral Data

General Cryptohalite Information

Chemical Formula:

(NH4)2SiF6

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

Empirical Formula:

(NH₄)₂SiF₆

Environment:

Volcanic sublimate. Dimorphous with bararite, the lower-temperature form.

IMA Status:

Valid Species (Pre-IMA) 1873

Locality:

Vesuvius, Campania, Italy. Link to MinDat.org Location Data.

Name Origin:

Named from the Greek for concealed and salt, for being admixed with sal ammoniac.

Synonym:

ICSD 18033

PDF 44-1484

Cryptohalite Image

Images:

Cryptohalite

Comments: White to colorless crystals of cryptohalite. The red color is due to admixtured (amorphous ?) selenium.
Location: Kladno, StredoceskÃ½ Kraj, Bohemia, Czech Republic. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

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

Cell Dimensions:

a = 8.395, Z = 4; V = 591.65 Den(Calc)= 2.00

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/I_o): 4.844(1), 2.422(0.45), 2.098(0.35),

Physical Properties of Cryptohalite

Cleavage:

{111} Perfect

Color:

Colorless, Gray, White.

Density:

2.011

Diaphaneity:

Transparent

Hardness:

2.5 - Finger Nail

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Cryptohalite

Optical Data:

Isotropic, n=1.369.

Calculated Properties of Cryptohalite

Electron Density:

Bulk Density (Electron Density)=2.02 gm/cc
note: Specific Gravity of Cryptohalite =2.00 gm/cc.

Fermion Index:

Fermion Index = 0.16
Boson Index = 0.84

Photoelectric:

PE_Cryptohalite= 0.97 barns/electron
U=PE_Cryptohalite x rElectron Density= 1.96 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cryptohalite is Not Radioactive

Cryptohalite Classification

Dana Class:

11.05.01.02 (11)Halide Complexes; Alumino-fluorides

(11.05)where (A)m B (X)6

(11.05.01)Dana Group

11.05.01.01 Hieratite K2SiF6 F m3m 4/m 3 2/m

11.05.01.02 Cryptohalite (NH4)2SiF6 F m3m 4/m 3 2/m

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

References:

NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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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Print or Cut-and-Paste your Cryptohalite Specimen Label here :

Cryptohalite

(NH4)2SiF6
Dana No: 11.05.01.02 Strunz No: 03.CH.15
Locality:

Notes:

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