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Ralstonite Mineral Data
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General Ralstonite Information
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 Chemical Formula: |
NaxMgxAl2-x(F,OH)6•(H2O) |
| Composition: |
Molecular Weight = 192.14 gm |
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Sodium 5.98 % Na 8.06 % Na2O |
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Magnesium 6.32 % Mg 10.49 % MgO |
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Aluminum 21.06 % Al 39.80 % Al2O3 |
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Hydrogen 2.10 % H 18.75 % H2O |
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Oxygen 24.98 % O |
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Fluorine 39.55 % F 39.55 % F |
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- %
F -16.65 % -O=F2 |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
| Empirical Formula: |
Na0.5Mg0.5Al1.5F4(OH)2•(H2O) |
| Environment: |
Alteration product of cryolite. |
| IMA Status: |
Valid Species (Pre-IMA) 1871 |
| Locality: |
Ivigtut, Greenland. Link to MinDat.org Location Data. |
| Name Origin: |
Named for J. Grier Ralston (1851-1880) of Norristown, Pennsylvania, USA, who first observed the mineral. |
| Name Pronunciation: |
Ralstonite + Pronunciation  |
| Synonym: |
Boldyrevite - impure ralstonite or gearksutite |
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ICSD 31345 |
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PDF 45-1331 |
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Ralstonite Image |
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Images:
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Ralstonite Cryolite
Comments: Massive cryolite with solution cavities lined with octahedral ralstonite crystals.
Location: Ivigtut, Greenland.
Scale: Picture size 0.5 cm.
© John Veevaert |
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Images:
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Gjerdingenite-Fe Ralstonite
Comments: SEM photomicrograph of gjerdingenite-Fe. The mineral is dusted with tiny crystals of two phases. At high magnification, one of them is seen to form cubes and is probably ralstonite.
Location: Gjerdingselva, Lunner, Oppland, Oslo Region, Norway.
Scale: Crystal length 0.5 mm.
© Canadian Mineralogist |
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Ralstonite Crystallography
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| Cell Dimensions: |
a = 9.89, Z = 8; V = 967.36 Den(Calc)= 2.64 |
| Crystal System: |
Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: F d3m |
| X Ray Diffraction: |
By Intensity(I/Io): 5.74(1), 1.765(0.85), 2.88(0.75), |
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Physical Properties of Ralstonite
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| Cleavage: |
{???} Perfect, {???} Perfect, {???} Perfect |
| Color: |
Colorless, White. |
| Density: |
2.55 |
| Diaphaneity: |
Transparent to translucent |
| Fracture: |
Brittle - Uneven - Very brittle fracture producing uneven fragments. |
| Hardness: |
4.5 - Between Fluorite and Apatite |
| Luminescence: |
Non-fluorescent. |
| Luster: |
Vitreous - Greasy |
| Streak: |
white |
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Optical Properties of Ralstonite
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| Optical Data: |
Isotropic, n=1.43. |
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Calculated Properties of Ralstonite
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| Electron Density: |
Bulk Density (Electron Density)=2.61 gm/cc
note: Specific Gravity of Ralstonite =2.64 gm/cc.
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| Fermion Index: |
Fermion Index = 0.0064477612
Boson Index = 0.9935522388 |
| Photoelectric: |
PERalstonite = 1.10 barns/electron
U=PERalstonite x rElectron Density= 2.87 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Ralstonite is Not Radioactive |
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Ralstonite Classification
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| Dana Class: |
11.06.12.01 (11)Halide Complexes; Alumino-fluorides |
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(11.06)with miscellaneous formulae |
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(11.06.12)Dana Group |
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11.06.12.01 Ralstonite NaxMgxAl2-x(F,OH)6•(H2O) F d3m 4/m 3 2/m |
| Strunz Class: |
03.CF.05 03 - HALIDES |
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03.C - Complex Halides |
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03.CF -Tekto-aluminofluorides |
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03.CF.05 Ralstonite NaxMgxAl2-x(F,OH)6•(H2O) F d3m 4/m 3 2/m |
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Other Ralstonite Information
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| References: |
NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32) |
| See Also: |
Links to other databases for Ralstonite :
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
15 - WWW-MINCRYST
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Print or Cut-and-Paste your Ralstonite Specimen Label here :
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Ralstonite
NaxMgxAl2-x(F,OH)6•(H2O)
Dana No: 11.06.12.01 Strunz No: 03.CF.05
Locality:
Notes:
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