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Braunite

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Formula:
Mn2+Mn63+(SiO4)O8
System:
Tetragonal
Colour:
Brownish black, ...
Hardness:
6 - 6½
Member of:
Name:
After Wilhelm von Braun (1790-1872), official and minister in Gotha, Germany, supporter of geology and mineralogy. He supplied the original material for the description of braunite.
Then Mn2+ analogue of neltnerite.

Classification of Braunite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
9.AG.05

9 : SILICATES (Germanates)
A : Nesosilicates
G : Nesosilicates with additional anions; cations in > [6] +- [6] coordination
7.5.1.3

7 : MULTIPLE OXIDES
5 : (AB)2X3
14.17.3

14 : Silicates not Containing Aluminum
17 : Silicates of Mn
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Type Occurrence of Braunite

Year of Discovery:
1827

Occurrences of Braunite

Geological Setting:
Metamorphism of manganese silicates and weathering product.

Physical Properties of Braunite

Sub-Metallic
Diaphaneity (Transparency):
Opaque
Colour:
Brownish black, steel-grey
Streak:
Black
Hardness (Mohs):
6 - 6½
Hardness (Vickers):
VHN100=920 - 1079 kg/mm2
Tenacity:
Brittle
Cleavage:
Perfect
{112} perfect.
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
4.72 - 4.83 g/cm3 (Measured)    4.86 g/cm3 (Calculated)

Crystallography of Braunite

Crystal System:
Tetragonal
Class (H-M):
4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:
I41/acd
Cell Parameters:
a = 9.41(4) Å, c = 18.8(2) Å
Ratio:
a:c = 1 : 1.998
Unit Cell Volume:
V 1,664.70 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Pyramidal {011} and {131}. Striated on {001} and {201} parallel to [010] Granular massive.
Twinning:
On {112} producing a combination with only a small reentrant angle (0°18') on е{011}.

Crystallographic forms of Braunite

Crystal Atlas:
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Braunite no.9 - Goldschmidt (1913-1926)
Braunite no.20 - Goldschmidt (1913-1926)
Braunite no.23 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Braunite

Type:
Anisotropic
Anisotropism:
Weak in air, distinct in oil - dark to lighter slate gray.
Colour in reflected light:
Grayish white with a brownish tinge.

Chemical Properties of Braunite

Formula:
Mn2+Mn63+(SiO4)O8
Essential elements:
All elements listed in formula:
Common Impurities:
Fe,Ca,B,Ba,Ti,Al,Mg

Relationship of Braunite to other Species

Member of:
Other Members of Group:
AbswurmbachiteCuMn63+(SiO4)O8
GatedaliteZrMn22+Mn43+SiO12
NeltneriteCaMn63+(SiO4)O8
9.AG.05AbswurmbachiteCuMn63+(SiO4)O8
9.AG.05NeltneriteCaMn63+(SiO4)O8
9.AG.05Braunite-IICaMn143+(SiO4)O20
9.AG.10Långbanite(Mn2+,Ca)4(Mn3+,Fe3+)9Sb5+(SiO4)2O16
9.AG.15MalayaiteCaSn(SiO4)O
9.AG.15TitaniteCaTi(SiO4)O
9.AG.15VanadomalayaiteCaV4+(SiO4)O
9.AG.15Natrotitanite(Na0.5Y0.5)Ti(SiO4)O
9.AG.20Cerite-(Ce)(Ce,Ca)9(Mg,Fe)(SiO4)3(HSiO4)4(OH)3
9.AG.20Cerite-(La)(La,Ce,Ca)9(Fe,Ca,Mg)(SiO4)3(HSiO4)4(OH)3
9.AG.20Aluminocerite-(Ce)(Ce,La,Ca)9(Al,Fe3+)(SiO4)3(HSiO4)4(OH)3
9.AG.25Trimounsite-(Y)Y2Ti2(SiO4)O5
9.AG.25Yftisite-(Y)(Y,Dy,Er)4(Ti,Sn)(SiO4)2O(F,OH)6
9.AG.30SitinakiteKNa2Ti4(SiO4)2O5(OH) · 4H2O
9.AG.35KittatinnyiteCa2Mn2Mn(SiO4)2(OH)4 · 9H2O
9.AG.40aNatisiteNa2Ti(SiO4)O
9.AG.40bParanatisiteNa2Ti(SiO4)O
9.AG.45Törnebohmite-(Ce)(Ce,La)2Al(SiO4)2(OH)
9.AG.45Törnebohmite-(La)(La,Ce)2Al(SiO4)2(OH)
9.AG.50Kuliokite-(Y)Y4Al(SiO4)2(OH)2F5
9.AG.55ChantaliteCaAl2(SiO4)(OH)4
9.AG.60MozartiteCaMn3+(SiO4)(OH)
9.AG.60VuagnatiteCaAl(SiO4)(OH)
9.AG.65HatruriteCa3(SiO4)O
9.AG.70JasmunditeCa11(SiO4)4O2S
9.AG.75AfwilliteCa3(HSiO4)2 · 2H2O
9.AG.80BultfonteiniteCa2(HSiO4)F · H2O
9.AG.85ZoltaiiteBaV24+V123+(SiO4)2O19
9.AG.90Tranquillityite(Fe2+,Ca)8(Zr,Y)2Ti3(SiO4)3O4
14.17.1RhodoniteMnSiO3
14.17.2TephroiteMn22+SiO4
14.17.4AlleghanyiteMn52+(SiO4)2(OH)2
14.17.5Ribbeite(Mn2+,Mg)5(SiO4)2(OH)2
14.17.6LeucophoeniciteMn72+(SiO4)3(OH)2
14.17.7JerrygibbsiteMn92+(SiO4)4(OH)2
14.17.8BementiteMn7Si6O15(OH)8
14.17.9Parsettensite(K,Na,Ca)7.5(Mn,Mg)49Si72O168(OH)50 · nH2O
14.17.10YofortieriteMn5Si8O20(OH)2 · 8-9H2O

Other Names for Braunite

Name in Other Languages:

Other Information

Other Information:
Weakly magnetic.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Braunite

Reference List:
Haidinger, W. (1827): On the crystalline Forms and Properties of the Manganese Ores.- Edinburgh Journal of Science, IV, 41

Haidinger, W. (1828): Mineralogische Beschreibung der Manganerze. I. Prismatoïdisches Manganerz, Manganit. II. Pyramidales Manganerz, Hausmannit. III. Untheilbares Manganerz, Psilomelan. IV. Brachytypes Manganerz, Braunit. V. Prismatisches Manganerz, Pyrolusit.- Poggendorffs Annalen der Physik und Chemie 14, 197-211

Turner, E. (1831): Chemical Examination of the Oxides of Manganese.- Transactions of the Royal Society of Edinburgh, Vol. II, 143-174

Breithaupt in Evreinov (1840), Ann. Phys.: 49: 204.

Switzer (1938), American Mineralogist: 23: 649.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 551-554.

American Mineralogist (1976): 61: 1226-1240.

Robie, R.A., Huebner, J.S., and Hemingway, B.S. (1995) Heat capacities and thermodynamic properties of braunite (Mn7SiO12) and rhodonite (MnSiO3). American Mineralogist: 80: 560-575.

Gutzmer, J. and Beukes, N. J. (1997): Mineralogy and mineral chemistry of oxide-facies manganese ores of the Postmasburg manganese field, South Africa. Mineralogical Magazine, 61, 213-232. [on stacking model for the braunite group]

Bevan, D.J.M. & R.L.Martin, The role of the coordination defect: A new structural description of four fluorite-related sesquioxide minerals, bixbyite, braunite, braunite II, parwelite, and their structural relationships. Journal of Solid State Chemistry 181,2250-2259(2008)

Internet Links for Braunite

Specimens:
The following Braunite specimens are currently listed for sale on minfind.com.

Localities for Braunite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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