Mineralogy Database

Selwynite Mineral Data

Search Webmineral :

General Selwynite Information

Help on Chemical  Formula: Chemical Formula: NaK(Be,Al)Zr2(PO4)4•2(H2O)
Help on Composition: Composition: Molecular Weight = 673.96 gm
   Potassium    5.80 %  K     6.99 % K2O
   Sodium       3.41 %  Na    4.60 % Na2O
   Zirconium   27.07 %  Zr   36.57 % ZrO2
   Beryllium    1.00 %  Be    2.78 % BeO
   Aluminum     1.00 %  Al    1.89 % Al2O3
   Phosphorus  18.38 %  P    42.12 % P2O5
   Hydrogen     0.60 %  H     5.35 % H2O
   Oxygen      42.73 %  O
              ______        ______ 
              100.00 %      100.30 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: NaKBe0.75Al0.25Zr2(PO4)4•2(H2O)
Help on Environment: Environment: In pegmatitic cavities.
Help on IMA Status: IMA Status: Approved IMA 1995
Help on Locality: Locality: A granite quarry near Wycheproof, NW Victoria, Australia. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: For A. R. C. Selwyn (1824-1902), founding director of the Geological Survey of Victoria, Australia.
Help on Name Pronunciation: Name Pronunciation: Selwynite + Pronunciation Say SELWYNITE
Help on Synonym: Synonym: IMA1993-037

Selwynite Image

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image


Comments: Dark purplish blue crystal of selwynite.
Location: A granite quarry near Wycheproof, NW Victoria, Australia.. Scale: Not Given.
© Museum Victoria

Selwynite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:2.60913
Help on Cell Dimensions: Cell Dimensions: a = 6.57, c = 17.142, Z = 2; V = 739.93 Den(Calc)= 3.02
Help on Crystal System: Crystal System: Tetragonal - Ditetragonal Dipyramidal H-M Symbol (4/m 2/m 2/m) Space Group: I 41/amd
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 6.161(1), 3.286(0.5), 3.039(0.3),

Physical Properties of Selwynite

Help on Cleavage: Cleavage: None
Help on Color: Color: Deep purplish blue.
Help on Density: Density: 2.94
Help on Diaphaneity: Diaphaneity: Transparent
Help on Fracture: Fracture: Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.
Help on Habit: Habit: Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)
Help on Hardness: Hardness: 4 - Fluorite
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: pale lavender

Optical Properties of Selwynite

Help on Dichroism (e): Dichroism (e): bluish lavender.
Help on Dichroism (w): Dichroism (w): pale bluish lavender.
Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.043 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.015 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2086,KPDmeas= 0.2143,KC= 0.2054
Ncalc = 1.6 - 1.62
Help on Optical Data: Optical Data: Uniaxial (+), w=1.624, e=1.636, bire=0.0120.

Calculated Properties of Selwynite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.91 gm/cc
note: Specific Gravity of Selwynite =3.02 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.04
Boson Index = 0.96
Help on Photoelectric: Photoelectric: PESelwynite = 37.76 barns/electron
U=PESelwynite x relectron= 109.72 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 80.55 (Gamma Ray American Petroleum Institute Units)
Concentration of Selwynite per GRapi unit = 1.24 (%)

Estimated Radioactivity from Selwynite - barely detectable


Selwynite Classification

Help on  Dana Class: Dana Class: (40)Hydrated Phosphates, etc
  (40.05)with miscellaneous formulae
  (40.05.04)Gainesite Group Gainesite Na2Zr2Be(PO4)4•1-2(H2O) I 41/amd 4/m 2/m 2/m Mccrillisite NaCs(Be,Li)Zr2(PO4)4•1-2(H2O) I 41/amd 4/m 2/m 2/m Selwynite NaK(Be,Al)Zr2(PO4)4•2(H2O) I 41/amd 4/m 2/m 2/m
Help on  Strunz Class: Strunz Class: 08.CA.20 08 - PHOSPHATES, ARSENATES, VANADATES
  08.C - Phosphates without Additional Anions, with H2O
  08.CA -With small and large/medium cations
08.CA.20 Gainesite Na2Zr2Be(PO4)4•1-2(H2O) I 41/amd 4/m 2/m 2/m
08.CA.20 Mccrillisite NaCs(Be,Li)Zr2(PO4)4•1-2(H2O) I 41/amd 4/m 2/m 2/m
08.CA.20 Selwynite NaK(Be,Al)Zr2(PO4)4•2(H2O) I 41/amd 4/m 2/m 2/m

Other Selwynite Information

Help on References: References: NAME( MinRec) PHYS. PROP.(Am.Min.,Vol.80,p1075,1995) OPTIC PROP.(MinRec)
Help on See Also: See Also: Links to other databases for Selwynite :
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

Search for Selwynite using:

Web webmineral.com
[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Selwynite :

Ask about Selwynite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Espaņol

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


Dana No: Strunz No: 08.CA.20





Dakota Matrix
Excalibur Minerals
Exceptional Minerals
Hudson Insitute
John Betts Fine Minerals
Mc Dougall Minerals
Mineral News
Rock and Mineral Shows
Weinrich Minerals, Inc.