Braunite-II Mineral Data

Braunite-II Mineral Data +

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General Braunite-II Information

Chemical Formula:

Mn++Mn+++6SiO12

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

Empirical Formula:

Mn²⁺Mn³⁺₆SiO₁₂

Environment:

Manganese oxide mineral deposits. Metamorphic and secondary weathering environments

IMA Status:

Not Approved IMA 1967

Locality:

Metamorphic, hydrothermal, and sedimentary rocks. Link to MinDat.org Location Data.

Name Origin:

Named after K. Braun (1790-1872) from Gotha, Germany.

Braunite-II Image

Images:

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

Axial Ratios:

a:c = 1:1.9904

Cell Dimensions:

a = 9.38, c = 18.67, Z = 8; V = 1,642.67 Den(Calc)= 4.89

Crystal System:

Tetragonal - Ditetragonal DipyramidalH-M Symbol (4/m 2/m 2/m) Space Group: I 4₁/acd

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.72(1), 1.656(0.7), 2.14(0.5),

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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

Cleavage:

[111] Perfect

Color:

Grayish black, Brownish gray, Dark brownish black.

Density:

4.72 - 4.82, Average = 4.76

Diaphaniety:

Opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

6-6.5 - Orthoclase-Pyrite

Luster:

Sub Metallic

Magnetism:

Nonmagnetic

Streak:

brownish gray black

Calculated Properties of Braunite-II

Electron Density:

r_electron=4.61 gm/cc
note: r_Braunite-II=4.89 gm/cc.

Fermion Index

Fermion Index = 0.00232
Boson Index = 0.99768

Photoelectric:

PE_Braunite-II= 16.86 barns/electron
U=PE_Braunite-II x r_electron= 77.73 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Braunite-II is Not Radioactive

Braunite-II Classification

Dana Class:

7.5.1.3 (7)Multiple Oxides

(7.5)where A B X2

(7.5.1)Humite group (Tetragonal: I41/acd) containing Si

7.5.1.1 Braunite-I MnMn6SiO12 I 4₁/acd 4/m 2/m 2/m

7.5.1.2 Neltnerite CaMn6SiO12 I 4₁/acd 4/m 2/m 2/m

7.5.1.3 Braunite-II * MnMn6SiO12 I 4₁/acd 4/m 2/m 2/m

7.5.1.4 Abswurmbachite CuMn6SiO12 I 4₁/acd 4/m 2/m 2/m

Strunz Class:

IV/X.00-00 IV - Oxides

IV/X - Unclassified Strunz Oxides

IV/X.00 - Oxide

Other Braunite-II Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Bull.Miner.,Vol.107-111,1984-1988)

See Also:

Links to other databases for Braunite-II :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas

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Print or Cut-and-Paste your Braunite-II Specimen Label here :

Braunite-II

Mn++Mn+++6SiO12
Dana No: 7.5.1.3 Strunz No: IV/X.00-00
Locality:

Notes: