Mineralogy Database

Braunite-II Mineral Data

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General Braunite-II Information

Help on Chemical  Formula: Chemical Formula: Mn++Mn+++6SiO12
Help on Composition: Composition: Molecular Weight = 604.64 gm
   Manganese  63.60 %  Mn   11.73 % MnO / 78.33 % Mn2O3
   Silicon     4.64 %  Si    9.94 % SiO2
   Oxygen     31.75 %  O
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Mn2+Mn3+6SiO12
Help on Environment: Environment: Manganese oxide mineral deposits. Metamorphic and secondary weathering environments
Help on IMA Status: IMA Status: Not Approved IMA 1967
Help on Locality: Locality: Metamorphic, hydrothermal, and sedimentary rocks. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named after K. Braun (1790-1872) from Gotha, Germany.
Help on Name Pronunciation: Name Pronunciation: Braunite-II Say BRAUNITE-II

Braunite-II Image

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  Braunite-II   Braunite-I

Comments: Crystals of braunite.
Location: Black Rock Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: Crystal size 1.3 cm.
© John Veevaert

Braunite-II Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:1.9904
Help on Cell Dimensions: Cell Dimensions: a = 9.38, c = 18.67, Z = 8; V = 1,642.67 Den(Calc)= 4.89
Help on Crystal System: Crystal System: Tetragonal - Ditetragonal Dipyramidal H-M Symbol (4/m 2/m 2/m) Space Group: I 41/acd
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.72(1), 1.656(0.7), 2.14(0.5),
Help on Forms: Forms:

Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize

S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu

Help on Above

Forms: ( 1 3 1) ( 1 3 3) ( 0 1 1) ( 1 1 0) ( 0 0 1)

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Physical Properties of Braunite-II

Help on Cleavage: Cleavage: {111} Perfect
Help on Color: Color: Grayish black, Brownish gray, Dark brownish black.
Help on Density: Density: 4.72 - 4.82, Average = 4.76
Help on Diaphaneity: Diaphaneity: Opaque
Help on Fracture: Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Help on Habit: Habit: Massive - Uniformly indistinguishable crystals forming large masses.
Help on Hardness: Hardness: 6-6.5 - Orthoclase-Pyrite
Help on Luster: Luster: Sub Metallic
Help on Magnetism: Magnetism: Nonmagnetic
Help on Streak: Streak: brownish gray black

Optical Properties of Braunite-II

Help on Optical Data: Optical Data: NCalc= 2.37 - from Gladstone-Dale relationship (KC = 0.2796) where Ncalc=Dcalc*KC+1
NCalc= 2.33 - from Gladstone-Dale relationship (KC = 0.2796) where Ncalc=Dmeas*KC+1

Calculated Properties of Braunite-II

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=4.61 gm/cc
note: Specific Gravity of Braunite-II =4.89 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0023216105
Boson Index = 0.9976783895
Help on Photoelectric: Photoelectric: PEBraunite-II = 16.86 barns/electron
U=PEBraunite-II x rElectron Density= 77.73 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Braunite-II is Not Radioactive

Braunite-II Classification

Help on  Dana Class: Dana Class: (07)Multiple Oxides
  (07.05)where A B X2
  (07.05.01)Humite group (Tetragonal: I41/acd) containing Si Braunite-I MnMn6SiO12 I 41/acd 4/m 2/m 2/m Neltnerite CaMn6SiO12 I 41/acd 4/m 2/m 2/m Braunite-II* MnMn6SiO12 I 41/acd 4/m 2/m 2/m Abswurmbachite CuMn6SiO12 I 41/acd 4/m 2/m 2/m
Help on  Strunz Class: Strunz Class: 09.AG.05 09 - SILICATES (Germanates)
  09.A - Nesosilicates
  09.AG -Nesosilicates with additional anions; cations in > [6] � [6] coordination
09.AG.05 Abswurmbachite CuMn6SiO12 I 41/acd 4/m 2/m 2/m
09.AG.05 Braunite-I MnMn6SiO12 I 41/acd 4/m 2/m 2/m
09.AG.05 Braunite-II* MnMn6SiO12 I 41/acd 4/m 2/m 2/m
09.AG.05 Neltnerite CaMn6SiO12 I 41/acd 4/m 2/m 2/m

Other Braunite-II Information

Help on References: References: NAME( Duda&Rejl90) PHYS. PROP.(Bull.Miner.,Vol.107-111,1984-1988)
Help on See Also: See Also: Links to other databases for Braunite-II :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Dana No: Strunz No: 09.AG.05





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