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Selwynite (Selwynit)

Additional Functions

Collectors Summary

Color lavendelblau
Streak color weiß
Hardness (Mohs) 4
Cleavages keine beobachtet
Fracture semimuschelig
Crystal System tetragonal, I41/amd

Chemism

Chemical formula

KNa(Be,Li)Zr2[PO4]4·2H2O

Chemical composition

Beryllium, Lithium, Natrium, Zirconium, Kalium, Phosphor, Sauerstoff, Wasserstoff

Unit weight: 668.947489725 u; Number of atoms in the formula: 31

Info

Empirical formula:

KNa(Be0.75Li0.25)Zr2[PO4]4·2H2O

Element

Symbol

Weight%

Atoms

Atoms%

Atom weight (u)

Sum weight (u)
Hydrogen

H

0.60

4

12.90

1.0079470

4.0317880
Lithium

Li

0.26

0.25

0.81

6.9412000

1.7353000
Beryllium

Be

1.01

0.75

2.42

9.0121823

6.7591367
Oxygen

O

43.05

18

58.06

15.9994300

287.9897400
Sodium

Na

3.44

1

3.23

22.9897702

22.9897702
Phosphorus

P

18.52

4

12.90

30.9737612

123.8950448
Potassium

K

5.84

1

3.23

39.0983100

39.0983100
Zirconium

Zr

27.27

2

6.45

91.2242000

182.4484000

Analysis wt%

Na2O : 4.77, K2O : 6.26, Cs2O : 0.70, CaO : 0.98, BeO : 1.43, MnO : 0.99, FeO : 0.49, Al2O3 : 1.04, ZrO2 : 33.76, HfO2 : 1.17, P2O5 : 40.90, SiO2 : 0.49, H2O : 5.40 (Ref: Canadian Mineralogist 95)

Strunz 9th edition incl. updates

8.CA.20

8: Phosphate, Arsenate, Vanadate
C: Phosphate ohne weitere Anionen, mit H2O
A: Mit kleinen und großen/mittelgroßen [Kationen]
20:Gainesit-Gruppe

Lapis Classification

VII/C.02-025

VII: PHOSPHATE, ARSENATE UND VANADATE ("Phosphate" des Registers immer einschließlich isotyper Arsenate und Vanadate!)
C: Wasserhaltige Phosphate, ohne fremde Anionen
2: Kleine und mittelgroße Kationen: Be und Al-Mn-Fe-Cu-Zn-Mg

Classification by Hölzel

8.CA.610

8: PHOSPHATES ARSENATES VANADATES
C: Phosphates (-Anions +Water)
A: Phosphates, C small

Dana 8th edition

40.05.04.03

40: Hydrated Phosphates, etc
05: Hydrated Phosphates, etc with miscellaneous formulae
04: Gainesite Group

IMA status

Anerkannt von der CNMNC

Mineral status

anerkanntes Mineral

Optical Properties

Color

lavendelblau

Streak color

weiß

max. Birefringence

0.012
Birefringence chart\! Selwynite title=Birefringence chart Selwynite

Michel-Levy Color Chart viewed according to the maximum birefringence (at 30μm). Mineral color is not taken into account. Click on the image to enlarge or change thickness.

RI value α / ω / n

1.624

RI value γ / ε

1.636

Ri mean

1.628

2V angle

Uniaxial (+)

Crystallography

Crystal System

tetragonal

Class (H-M)

4/mmm

Space Group number

141

Space Group

I41/amd

Cell parameters a (Å)

6.570

Cell parameters b (Å)

-

Cell parameters c (Å)

17.142

Cell parameters a/b or c/a

2.609

Cell parameters c/b

-

Cell parameters α

90°

Cell parameters β

90°

Cell parameters γ

120°

Z

2

Volumne (ų)

739.933

X-Ray Powder Diffraction

6.16(100),
4.291(20),
3.286(50),
3.039(30),
2.895(20),
2.609(10),
2.431(10),
2.169(10)
XRD chart Selwynite

Calculated from d-spacing and intensity at 0.1541838 nm (Cu)

Physical Properties

Hardness (Mohs)

4

VHN (Hardness Vickers)

190 (ungefähre Angabe abgeleitet aus der Mohshärte)

Density (g/cm³)

2.94 (gemessen)

3.002 ( ρ calc. Mineralienatlas )

Cleavages

keine beobachtet

Fracture

semimuschelig

(Co-)Type locality

(Co-)Type locality

Australien/Victoria/Wycheproof/Granitbruch

Preface

Author (Name, Year)

Birch & Pring & Foord, 1995

References

Canadian Mineralogist 33 (1995), 55

Other languages

German

Selwynit

Spanish

Selwynita

English

Selwynite

French

Selwynite

Alternative Name

Potassian Gainesite

CNMNC (IMA)-Number

IMA 1993-037

CNMNC symbol

Symbol

Swy