Knorringite Mineral Data

General Knorringite Information

Chemical Formula:

Mg3Cr2(SiO4)3

Composition:

Molecular Weight = 453.16 gm

Magnesium 16.09 % Mg 26.68 % MgO

Chromium 22.95 % Cr 33.54 % Cr₂O₃

Silicon 18.59 % Si 39.78 % SiO₂

Oxygen 42.37 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg₃Cr₂(SiO₄)₃

Environment:

Rare component of ultramafic kimberlite nodules.

IMA Status:

Approved IMA 1968

Locality:

Kao kimberlite pipe, Lesotho. Link to MinDat.org Location Data.

Name Origin:

Named for Oleg von Knorring (1915-1994), Department of Earth Sciences, Leeds University, Leeds, England.

Name Pronunciation:

Knorringite + Pronunciation

Synonym:

ICSD 27371

PDF 35-536

Knorringite Crystallography

Cell Dimensions:

a = 11.65, Z = 8; V = 1,581.17 Den(Calc)= 3.81

Crystal System:

Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: I a3d

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Physical Properties of Knorringite

Cleavage:

None

Color:

Blue green, Green.

Density:

3.756

Diaphaneity:

Transparent to Translucent

Hardness:

6-7 - Orthoclase-Quartz

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Knorringite

Gladstone-Dale:

CI meas= 0.084 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.097 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2108,KPDmeas= 0.2138,KC= 0.2334
Ncalc = 1.88 - 1.89

Optical Data:

Isotropic, n=1.803.

Calculated Properties of Knorringite

Electron Density:

Bulk Density (Electron Density)=3.68 gm/cc
note: Specific Gravity of Knorringite =3.76 gm/cc.

Fermion Index:

Fermion Index = 0.04
Boson Index = 0.96

Photoelectric:

PE_Knorringite= 6.17 barns/electron
U=PE_Knorringite x rElectron Density= 22.69 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Knorringite is Not Radioactive

Knorringite Classification

Dana Class:

51.04.03a.04 (51)Nesosilicate Insular SiO4 Groups Only

(51.04)with cations in [6] and >[6] coordination

(51.04.03a)Garnet group (Pyralspite series)

51.04.03a.01 Pyrope Mg3Al2(SiO4)3 I a3d 4/m 3 2/m

51.04.03a.02 Almandine Fe3Al2(SiO4)3 I a3d 4/m 3 2/m

51.04.03a.03 Spessartine Mn3Al2(SiO4)3 I a3d 4/m 3 2/m

51.04.03a.04 Knorringite Mg3Cr2(SiO4)3 I a3d 4/m 3 2/m

51.04.03a.05 Majorite Mg3(Fe,Al,Si)2(SiO4)3 I a3d 4/m 3 2/m

51.04.03a.06 Calderite (Mn,Ca)3(Fe,Al)2(SiO4)3 I a3d 4/m 3 2/m

Strunz Class:

09.AD.25 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AD -Nesosilicates without additional anions;

09.AD.25 Almandine Fe3Al2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Calderite (Mn,Ca)3(Fe,Al)2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Andradite Ca3Fe2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Goldmanite Ca3(V,Al,Fe)2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Hibschite Ca3Al2(SiO4)3-x(OH)4x(x=0.2-1.5) I a3d 4/m 3 2/m

09.AD.25 Knorringite Mg3Cr2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Grossular Ca3Al2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Henritermierite Ca3(Mn,Al)2(SiO4)2(OH)4 I 4₁/acd 4/m 2/m 2/m

09.AD.25 Katoite Ca3Al2(SiO4)3-x(OH)4xx=1.5-3 I a3d 4/m 3 2/m

09.AD.25 Majorite Mg3(Fe,Al,Si)2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Kimzeyite Ca3(Zr,Ti)2(Si,Al,Fe)3O12 I a3d 4/m 3 2/m

09.AD.25 Morimotoite Ca3TiFeSi3O12 I a3d 4/m 3 2/m

09.AD.25 Pyrope Mg3Al2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Spessartine Mn3Al2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Schorlomite Ca3(Ti,Fe,Al)2[(Si,Fe,Fe)O4]3 I a3d 4/m 3 2/m

09.AD.25 Uvarovite Ca3Cr2(SiO4)3 I a3d 4/m 3 2/m

09.AD.25 Wadalite Ca6Al5Si2O16Cl3 I 43d 4 3m

09.AD.25 Holtstamite! Ca3(Al,Mn)2(SiO4)2(OH)4 I 4₁/acd 4/m 2/m 2/m

Other Knorringite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Knorringite :
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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Knorringite

Mg3Cr2(SiO4)3
Dana No: 51.04.03a.04 Strunz No: 09.AD.25
Locality:

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