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Knorringite (Knorringit)

Collectors Summary

Color blau grün, grün
Streak color weiß
Hardness (Mohs) 6 - 7
Solubility ++ HF
Crystal System kubisch, Ia3d

Chemism

Chemical formula

{Mg3}[Cr3+2](Si3)O12

Chemical composition

Chrom, Magnesium, Silicium, Sauerstoff

Unit weight: 453.15725 u; Number of atoms in the formula: 20

Info

Empirical formula:

{Mg3}[Cr2](Si3)O12

Element

Symbol

Weight%

Atoms

Atoms%

Atom weight (u)

Sum weight (u)
Oxygen

O

42.37

12

60.00

15.9994300

191.9931600
Magnesium

Mg

16.09

3

15.00

24.3050600

72.9151800
Silicon

Si

18.59

3

15.00

28.0855300

84.2565900
Chromium

Cr

22.95

2

10.00

51.9961600

103.9923200

Analysis wt%

SiO2 : 39.92, Al2O3 : 9.74, Cr2O3 : 17.47, Fe2O3 : 1.20, FeO : 6.53, MnO : 0.60, MgO : 16.97, CaO : 8.14 (Ref: American Mineralogist 68)

Strunz 9th edition incl. updates

9.AD.25

9: Silikate (Germanate)
A: Inselsilikate (Nesosilikate)
D: Insel(Neso)silikate ohne weitere Anionen; Kationen in oktahedraler [6] und gewöhnlich größerer Koordination
25:Granat-Gruppe

Lapis Classification

VIII/A.08-050

VIII: SILIKATE
A: Inselsilikate mit [SiO4] 4--Baugruppen
8: Kationen in kubischer und oktaedrischer Koordination [8+6]; Granat-Gruppe

Classification by Hölzel

9.AC.160

9: SILICATES
A: Nesosilicates
C: Garnet-Group
1: Pyralspites - 8-coord. Mg, Fe(2+), Mn(2+); Pyrope - Spessartine-Group

Dana 8th edition

51.04.03a.04

51: Nesosilicate Minerals
04: Nesosilicates Nesosilicate Insular SiO4 Groups Only with cations in [6] and >[6] coordination
03a: Garnet group (Pyralspite series)

IMA status

Anerkannt von der CNMNC

Mineral status

anerkanntes Mineral

IMA Classification

IMA Classification

 Garnet supergroup  ⇒ Silicate garnets; Garnet group (Z charge 12)

Optical Properties

Color

blau grün, grün

Streak color

weiß

Diaphaneity (Transparency)

transparent bis durchscheinend

RI value α / ω / n

1.803

Ri mean

1.803

2V angle

Isotropisch

Crystallography

Crystal System

kubisch

Class (H-M)

m3m

Space Group number

230

Space Group

Ia3d

Cell parameters a (Å)

11.596

Cell parameters b (Å)

-

Cell parameters c (Å)

-

Cell parameters a/b or c/a

1

Cell parameters c/b

-

Cell parameters α

90°

Cell parameters β

90°

Cell parameters γ

90°

Z

8

Volumne (ų)

1559.282

X-Ray Powder Diffraction

2.900(70),
2.593(100),
2.473(40),
2.367(40),
2.274(20),
1.834(20),
1.609(40),
1.549(60)
XRD chart Knorringite

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

Crystal Structure 3D

Open larger view

Physical Properties

Hardness (Mohs)

6 - 7

VHN (Hardness Vickers)

960 (ungefähre Angabe abgeleitet aus der Mohshärte)

Density (g/cm³)

3.756

3.86 ( ρ calc. Mineralienatlas )

Instability

++ HF

(Co-)Type locality

(Co-)Type locality

Lesotho/Butha-Buthe, Distrikt/Kao Kimberlit-Pipe

Preface

Author (Name, Year)

Nixon & Hornung, 1968

References

American Mineralogist 53 (1968), 1833

Amélie Juhin, Guillaume Morin, Erik Elkaïm, Daniel J. Frost, Michel Fialin, Farid Juillot, Georges Calas: Structure refinement of a synthetic knorringite, Mg3(Cr0.8Mg0.1Si0.1)2(SiO4)3. American Mineralogist 95(2010) S.59-63.

Grew, E.S., Locock, A.J., Mills, S.J., Galuskina, I.O., Galuskin, E.V., Halenius, U., 2012; Nomenclature of the garnet supergroup. American Mineralogist; preprint December 2012 - [Formel].

IMA group assignments

Other languages

German

Knorringit

Spanish

Knorringita

French

Knorringite

English

Knorringite

Russian

Кноррингит

CNMNC (IMA)-Number

IMA 1968-010

CNMNC symbol

Symbol

Krr

Locations with GPS information

IDs

GUSID (Global unique identifier short form) mAS5gbYwiUOISNq_NWSqew
GUID (Global unique identifier) 81B90498-30B6-4389-8848-DABF3564AA7B
Database ID 1999