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Selwynite

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About SelwyniteHide

Alfred Richard Cecil Selwyn
Formula:
NaK(Be,Al)Zr2(PO4)4 · 2H2O
Colour:
Deep purplish blue
Lustre:
Vitreous
Hardness:
4
Crystal System:
Tetragonal
Member of:
Name:
The name honours Alfred Richard Cecil Selwyn (1824-1902), British born geologist, founding Director of the Geological Survey of Victoria, Australia (1860-1869), and the second Director of the Geological Survey of Canada (1869-1895).
Gainesite Group


Classification of SelwyniteHide

Approved
8.CA.20

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
A : With small and large/medium cations
40.5.4.3

40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
5 : AXO4·xH2O

Physical Properties of SelwyniteHide

Vitreous
Transparency:
Transparent, Translucent
Colour:
Deep purplish blue
Streak:
Lavender, pale
Hardness:

Optical Data of SelwyniteHide

Type:
Uniaxial (+)
RI values:
nω = 1.624 nε = 1.636
Max Birefringence:
δ = 0.012
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate

Chemical Properties of SelwyniteHide

Formula:
NaK(Be,Al)Zr2(PO4)4 · 2H2O
IMA Formula:
NaKBeZr2(PO4)4 · 2H2O
Common Impurities:
Rb,Ca,Sr,Ba,Mg,Mn,Fe,Cs,Ce,Hf,P,Si,F

Crystallography of SelwyniteHide

Crystal System:
Tetragonal
Cell Parameters:
a = 6.57 Å, c = 17.14 Å
Ratio:
a:c = 1 : 2.609
Unit Cell V:
739.85 ų (Calculated from Unit Cell)

Type Occurrence of SelwyniteHide

Synonyms of SelwyniteHide

Other Language Names for SelwyniteHide

German:Selwynit
Spanish:Selwynita

Relationship of Selwynite to other SpeciesHide

Member of:
Other Members of this group:
GainesiteNa(Na,K)(Be,Li)Zr2(PO4)4 · 1.5-2H2OTet. 4mm : I41md
MccrillisiteNaCs(Be,Li)Zr2(PO4)4 · 1-2H2OTet. 4/mmm (4/m 2/m 2/m) : I41/amd

Related Minerals - Nickel-Strunz GroupingHide

8.CA.DavidlloyditeZn3(AsO4)2·4H2O Tric. 1 : P1
8.CA.ApexiteNaMg(PO4)·9H2OTric. 1 : P1
8.CA.05FransoletiteCa3Be2(PO4)2(HPO4)2 · 4H2OMon.
8.CA.05ParafransoletiteCa3Be2(PO4)2(HPO4)2 · 4H2OTric. 1 : P1
8.CA.10EhrleiteCa4Be3Zn2(PO4)6 · 9H2OTric. 1 : P1
8.CA.15FaheyiteBe2Mn2+Fe3+2(PO4)4 · 6H2OTrig. 3 2 : P31 2 1
8.CA.20GainesiteNa(Na,K)(Be,Li)Zr2(PO4)4 · 1.5-2H2OTet. 4mm : I41md
8.CA.20MccrillisiteNaCs(Be,Li)Zr2(PO4)4 · 1-2H2OTet. 4/mmm (4/m 2/m 2/m) : I41/amd
8.CA.25PahasapaiteLi8(Ca,Li,K)10.5Be24(PO4)24 · 38H2OIso. 2 3 : I2 3
8.CA.30HopeiteZn3(PO4)2 · 4H2OOrth. mmm (2/m 2/m 2/m) : Pnma
8.CA.30ArsenohopeiteZn3(AsO4)2 · 4H2OOrth. mmm (2/m 2/m 2/m) : Pnma
8.CA.35WarikahniteZn3(AsO4)2 · 2H2OTric.
8.CA.40PhosphophylliteZn2Fe(PO4)2 · 4H2OMon. 2/m : P21/b
8.CA.45ParascholziteCaZn2(PO4)2 · 2H2OMon.
8.CA.45ScholziteCaZn2(PO4)2 · 2H2OOrth. mmm (2/m 2/m 2/m) : Pbcm
8.CA.50KeyiteCu2+3Zn4Cd2(AsO4)6 · 2H2OMon. 2/m
8.CA.55PushcharovskiteK0.6Cu18(AsO4)(HAsO4)10(H2AsO4)4(OH)9.6·18.6H2OTric.
8.CA.60ProsperiteCa2Zn4(AsO4)4 · H2OMon.
8.CA.65GengenbachiteKFe3+3(HPO4)4(H2PO4)2 · 6H2OTrig. 3m : P3 1c
8.CA.70ParahopeiteZn3(PO4)2 · 4H2OTric. 1 : P1

Related Minerals - Dana Grouping (8th Ed.)Hide

40.5.4.KaňkiteFeAsO4 · 3.5H2OMon.
40.5.4.1GainesiteNa(Na,K)(Be,Li)Zr2(PO4)4 · 1.5-2H2OTet. 4mm : I41md
40.5.4.2MccrillisiteNaCs(Be,Li)Zr2(PO4)4 · 1-2H2OTet. 4/mmm (4/m 2/m 2/m) : I41/amd

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for SelwyniteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Birch, W.D. and D.A.Henry (1993), Phosphate Minerals of Victoria: 39.
Birch, W. D., Pring, A. & Foord, E. E. (1995): Selwynite, NaK(Be,Al)Zr2(PO4)4.2H2O, a new gainesite-like mineral from Wycheproof, Victoria, Australia. Canadian Mineralogist: 33: 55-58.
Mineralogical Record: 27: 120.

Internet Links for SelwyniteHide

Localities for SelwyniteHide

ⓘ - Click for 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Australia (TL)
 
  • Victoria
    • Buloke Shire
      • Wycheproof
CM 1995, 55-8; W.D.Birch. Phosphate Minerals of Victoria. The Mineralogical Society of Victoria special publication No. 3 pp. 28-32
Mineral and/or Locality  
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