Cryptohalite
A valid IMA mineral species - grandfathered
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About Cryptohalite
Formula:
(NH4)2[SiF6]
Colour:
Colourless, white, grey; colourless in transmitted light
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
2.004
Crystal System:
Isometric
Name:
From the Greek κρυπτός, concealed, and άλς, salt, in allusion to its intimate mixture with salammoniac in the type locality occurrence.
Dimorph of:
Isostructural with:
This page provides mineralogical data about Cryptohalite.
Unique Identifiers
Mindat ID:
1163
Long-form identifier:
mindat:1:1:1163:7
GUID
(UUID V4):
(UUID V4):
bbf7f758-8f8b-4740-b26a-1e6fc1729d93
IMA Classification of Cryptohalite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(NH4)2SiF6
First published:
1873
Classification of Cryptohalite
3.CH.15
3 : HALIDES
C : Complex halides
H : Silicofluorides
3 : HALIDES
C : Complex halides
H : Silicofluorides
11.5.1.2
11 : HALIDE COMPLEXES
5 : AmBX6
11 : HALIDE COMPLEXES
5 : AmBX6
8.12.5
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
12 : Fluorborates (BF'4) and fluosilicates (SiF''6)
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Symbol | Source | Reference |
---|---|---|
Cphl | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Cryptohalite
Vitreous
Colour:
Colourless, white, grey; colourless in transmitted light
Hardness:
2½ on Mohs scale
Cleavage:
Perfect
on {111}
on {111}
Density:
2.004 g/cm3 (Measured) 2.029 g/cm3 (Calculated)
Optical Data of Cryptohalite
Type:
Isotropic
Chemistry of Cryptohalite
Mindat Formula:
(NH4)2[SiF6]
Elements listed:
Crystallography of Cryptohalite
Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fm3m
Cell Parameters:
a = 8.39 Å
Unit Cell 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.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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Big Balls | Small Balls | Just Balls | Spacefill
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Big Balls | Small Balls | Just Balls | Spacefill
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
---|---|---|---|---|---|---|---|
0012983 | Cryptohalite | Schlemper E O, Hamilton W C, Rush J J (1966) Structure of cubic ammonium fluosilicate: Neutron-diffraction and neutron-inelastic-scattering studies Journal of Chemical Physics 44 2499-2505 | 1966 | synthetic | 0 | 293 | |
0017907 | Cryptohalite | Bozorth R (1922) The Crystal Structure of Ammonium Fluosilicate _cod_database_code 1010992 Journal of the American Chemical Society 44 1066-1070 | 1922 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
4.844 Å | (100) |
2.422 Å | (45) |
2.098 Å | (35) |
4.195 Å | (25) |
2.967 Å | (18) |
1.615 Å | (18) |
2.531 Å | (8) |
Comments:
Synthetic.
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 7: Great Oxidation Event | <2.4 |
45b : [Other oxidized fumarolic minerals] | |
Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
50 : Coal and/or oil shale minerals | <0.36 |
Stage 10b: Anthropogenic minerals | <10 Ka |
54 : Coal and other mine fire minerals (see also #51 and #56) |
Type Occurrence of Cryptohalite
Place of Conservation of Type Material:
No defined type material.
Associated Minerals at Type Locality:
Synonyms of Cryptohalite
Criptoalite (in part)
Other Language Names for Cryptohalite
German:Kryptohalit
Russian:Криптогалит
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
3.CH.05 | Malladrite | Na2[SiF6] |
3.CH.10 | Bararite | (NH4)2[SiF6] |
3.CH.15 | Hieratite | K2[SiF6] |
3.CH.20 | Demartinite | K2[SiF6] |
3.CH.25 | Knasibfite | K3Na4[SiF6]3[BF4] |
3.CH.30 | Heklaite | KNaSiF6 |
Other Information
Notes:
Soluble in cold water, more so in hot water.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Cryptohalite
mindat.org URL:
https://www.mindat.org/min-1163.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Cryptohalite
Reference List:
Localities for Cryptohalite
Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Czech Republic | |
| Zacek et al. (1995) |
Palache et al. (1951) | |
David Parfitt collection | |
| Harapát |
| Žáček et al. (1998) |
| Dalibor Matýsek |
Germany | |
| Walenta (1992) |
| XRD and EDX-analysed by Günter Blaß +1 other reference |
Iceland | |
| Balić-Žunić et al. (2016) |
India | |
| Palache et al. (1951) |
Italy (TL) | |
| Palache et al. (1951) +1 other reference |
Pelloux (1927) +2 other references | |
Poland | |
| Fabiańska et al. (Poland) |
| Łukasz Kruszewski (2012) |
Saint Helena, Ascension and Tristan da Cunha | |
Bailey | |
Tajikistan | |
| PXRD |
USA | |
| |
| Finkelman et al. (1) +1 other reference |
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Kladno District, Central Bohemian Region, Czech Republic