Braunite-I Mineral Data

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General Braunite-I 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:

Valid Species (Pre-IMA) 1831

Locality:

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

Name Origin:

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

Name Pronunciation:

Braunite-I

Braunite-I Image

Images:

Braunite-I Braunite-II

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

Images:

Braunite-I Donpeacorite

Comments: Brown crystalline massive donpeacorite with dark brown black braunite.
Location: Zinc Corporation of America Mine #4, Balmat, Saint Lawrence County, New York, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Braunite-I Macfallite Johnsenite-(Ce)

Comments: Tiny - less than 1mm - maroon crystals of mcfallite suspended as inclusions in massive quartz along with larger spots of brown johnsenite-(Ce) and braunite.
Location: Artur mine, Jaguaracu, Minas Gerais, Brazil. Scale: Overall 3 x 2.5 slab.
© Tom Loomis / Dakota Matrix

Braunite-I 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),

Forms:

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

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Physical Properties of Braunite-I

Cleavage:

{111} Perfect

Color:

Grayish black, Brownish gray, Dark brownish black.

Density:

4.72 - 4.82, Average = 4.76

Diaphaneity:

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

Luminescence:

Non-fluorescent.

Luster:

Sub Metallic

Magnetism:

Nonmagnetic

Streak:

brownish gray black

Optical Properties of Braunite-I

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-I

Electron Density:

Bulk Density (Electron Density)=4.61 gm/cc
note: Specific Gravity of Braunite-I =4.89 gm/cc.

Fermion Index:

Fermion Index = 0.0023216105
Boson Index = 0.9976783895

Photoelectric:

PE_Braunite-I= 16.86 barns/electron
U=PE_Braunite-I x rElectron Density= 77.73 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Braunite-I is Not Radioactive

Braunite-I Classification

Dana Class:

07.05.01.01 (07)Multiple Oxides

(07.05)where A B X2

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

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

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

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

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

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-I Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Braunite-I :
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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Braunite-I

Mn++Mn+++6SiO12
Dana No: 07.05.01.01 Strunz No: 09.AG.05
Locality:

Notes: