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Ralstonite Mineral Data

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General Ralstonite Information

Help on Chemical  Formula: Chemical Formula: NaxMgxAl2-x(F,OH)6•(H2O)
Help on Composition: Composition: Molecular Weight = 192.14 gm
   Sodium      5.98 %  Na    8.06 % Na2O
   Magnesium   6.32 %  Mg   10.49 % MgO
   Aluminum   21.06 %  Al   39.80 % Al2O3
   Hydrogen    2.10 %  H    18.75 % H2O
   Oxygen     24.98 %  O
   Fluorine   39.55 %  F    39.55 % F
                -   %   F   -16.65 % -O=F2    
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Na0.5Mg0.5Al1.5F4(OH)2•(H2O)
Help on Environment: Environment: Alteration product of cryolite.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1871
Help on Locality: Locality: Ivigtut, Greenland. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for J. Grier Ralston (1851-1880) of Norristown, Pennsylvania, USA, who first observed the mineral.
Help on Name Pronunciation: Name Pronunciation: Ralstonite + Pronunciation Say RALSTONITE
Help on Synonym: Synonym: Boldyrevite - impure ralstonite or gearksutite
  ICSD 31345
  PDF 45-1331

Ralstonite Image

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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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  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

Ralstonite Crystallography

Help on Cell Dimensions: Cell Dimensions: a = 9.89, Z = 8; V = 967.36 Den(Calc)= 2.64
Help on Crystal System: Crystal System: Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: F d3m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 5.74(1), 1.765(0.85), 2.88(0.75),

Physical Properties of Ralstonite

Help on Cleavage: Cleavage: {???} Perfect, {???} Perfect, {???} Perfect
Help on Color: Color: Colorless, White.
Help on Density: Density: 2.55
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Brittle - Uneven - Very brittle fracture producing uneven fragments.
Help on Hardness: Hardness: 4.5 - Between Fluorite and Apatite
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous - Greasy
Help on Streak: Streak: white

Optical Properties of Ralstonite

Help on Optical Data: Optical Data: Isotropic, n=1.43.

Calculated Properties of Ralstonite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.61 gm/cc
note: Specific Gravity of Ralstonite =2.64 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0064477612
Boson Index = 0.9935522388
Help on Photoelectric: Photoelectric: PERalstonite = 1.10 barns/electron
U=PERalstonite x rElectron Density= 2.87 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Ralstonite is Not Radioactive

Ralstonite Classification

Help on  Dana Class: Dana Class: (11)Halide Complexes; Alumino-fluorides
  (11.06)with miscellaneous formulae
  (11.06.12)Dana Group Ralstonite NaxMgxAl2-x(F,OH)6•(H2O) F d3m 4/m 3 2/m
Help on  Strunz Class: Strunz Class: 03.CF.05 03 - HALIDES
  03.C - Complex Halides
  03.CF -Tekto-aluminofluorides
03.CF.05 Ralstonite NaxMgxAl2-x(F,OH)6•(H2O) F d3m 4/m 3 2/m

Other Ralstonite Information

Help on References: References: NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)
Help on See Also: 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

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Dana No: Strunz No: 03.CF.05





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