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Braunite

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Formula:
Mn2+Mn3+6(SiO4)O8
Colour:
Brownish black, steel-grey
Lustre:
Sub-Metallic
Hardness:
6 - 6½
Specific Gravity:
4.72 - 4.83
Crystal System:
Tetragonal
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.
The Mn2+ analogue of neltnerite.

Compare also braunite-II.


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Classification of BrauniteHide

Approved, 'Grandfathered' (first described prior to 1959)
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

Physical Properties of BrauniteHide

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

Optical Data of BrauniteHide

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 BrauniteHide

Formula:
Mn2+Mn3+6(SiO4)O8
IMA Formula:
Mn2+Mn3+6SiO12
Common Impurities:
Fe,Ca,B,Ba,Ti,Al,Mg

Crystallography of BrauniteHide

Crystal System:
Tetragonal
Class (H-M):
4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:
I41/acd
Cell Parameters:
a = 9.432 Å, c = 18.703 Å
Ratio:
a:c = 1 : 1.983
Unit Cell V:
1,663.87 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}.
Comment:
Cell from de Villiers (1975). Cell dimensions variable: a = 9.36-9.45, c = 18.60-18.97 Å.

Crystallographic forms of BrauniteHide

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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Transparency
Opaque | Translucent | Transparent

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X-Ray Powder DiffractionHide

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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Type Occurrence of BrauniteHide

Synonyms of BrauniteHide

Other Language Names for BrauniteHide

Relationship of Braunite to other SpeciesHide

Member of:
Other Members of this group:
AbswurmbachiteCuMn3+6(SiO4)O8Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
Braunite-IICaMn3+14(SiO4)O20Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
GatedaliteZrMn2+2Mn3+4SiO12Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
NeltneriteCaMn3+6(SiO4)O8Tet. 4/mmm (4/m 2/m 2/m) : I41/acd

Common AssociatesHide

Associated Minerals Based on Photo Data:
Calcite17 photos of Braunite associated with Calcite on mindat.org.
Baryte14 photos of Braunite associated with Baryte on mindat.org.
Quartz11 photos of Braunite associated with Quartz on mindat.org.
Andradite11 photos of Braunite associated with Andradite on mindat.org.
Rhodonite8 photos of Braunite associated with Rhodonite on mindat.org.
Namansilite8 photos of Braunite associated with Namansilite on mindat.org.
Hausmannite6 photos of Braunite associated with Hausmannite on mindat.org.
Piemontite6 photos of Braunite associated with Piemontite on mindat.org.
Hollandite6 photos of Braunite associated with Hollandite on mindat.org.
Unnamed (Mn-analogue of Ferriakasakaite-(La))5 photos of Braunite associated with Unnamed (Mn-analogue of Ferriakasakaite-(La)) on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.AG.05AbswurmbachiteCuMn3+6(SiO4)O8Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
9.AG.05NeltneriteCaMn3+6(SiO4)O8Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
9.AG.05Braunite-IICaMn3+14(SiO4)O20Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
9.AG.10LångbaniteMn2+4Mn3+9Sb5+O16(SiO4)2Trig. 3m : P3m1
9.AG.15MalayaiteCaSn(SiO4)OMon.
9.AG.15TitaniteCaTi(SiO4)OMon. 2/m : P21/b
9.AG.15VanadomalayaiteCaV4+(SiO4)OMon.
9.AG.15Natrotitanite(Na0.5Y0.5)Ti(SiO4)OMon. 2/m : B2/b
9.AG.15ŻabińskiiteCa[Al0.5(Ta,Nb)0.5)](SiO4)OTric. 1
9.AG.20Cerite-(Ce)(Ce,Ca)9(Mg,Fe)(SiO4)3(HSiO4)4(OH)3Trig. 3m : R3c
9.AG.20Cerite-(La)(La,Ce,Ca)9(Fe,Ca,Mg)(SiO4)3(HSiO4)4(OH)3Trig. 3m : R3c
9.AG.20Aluminocerite-(Ce)(Ce,La,Ca)9(Al,Fe3+)(SiO4)3(HSiO4)4(OH)3Trig. 3m : R3c
9.AG.25Trimounsite-(Y)Y2Ti2(SiO4)O5Mon.
9.AG.25Yftisite-(Y)(Y,Dy,Er)4(Ti,Sn)(SiO4)2O(F,OH)6
9.AG.25Mieite-(Y)Y4Ti(SiO4)2O[F,(OH)]6Orth. mmm (2/m 2/m 2/m) : Cmcm
9.AG.30SitinakiteKNa2Ti4(SiO4)2O5(OH) · 4H2OTet.
9.AG.35KittatinnyiteCa2Mn2Mn(SiO4)2(OH)4 · 9H2OHex.
9.AG.40aNatisiteNa2Ti(SiO4)OTet.
9.AG.40bParanatisiteNa2Ti(SiO4)OOrth.
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)4Tet. 4/m : I41/a
9.AG.60MozartiteCaMn3+(SiO4)(OH)Orth. 2 2 2 : P21 21 21
9.AG.60VuagnatiteCaAl(SiO4)(OH)Orth.
9.AG.65HatruriteCa3(SiO4)OTrig.
9.AG.70JasmunditeCa11(SiO4)4O2STet. 4 2m : I4m2
9.AG.75AfwilliteCa3(HSiO4)2 · 2H2OMon. m : Bb
9.AG.80BultfonteiniteCa2(HSiO4)F · H2OTric.
9.AG.85ZoltaiiteBaV4+2V3+12(SiO4)2O19Trig. 3 : P3
9.AG.90Tranquillityite(Fe2+,Ca)8(Zr,Y)2Ti3(SiO4)3O12Hex.

Related Minerals - Dana Grouping (8th Ed.)Hide

7.5.1.2NeltneriteCaMn3+6(SiO4)O8Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
7.5.1.3Braunite-IICaMn3+14(SiO4)O20Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
7.5.1.4AbswurmbachiteCuMn3+6(SiO4)O8Tet. 4/mmm (4/m 2/m 2/m) : I41/acd

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.17.1RhodoniteCaMn3Mn(Si5O15)Tric. 1
14.17.2TephroiteMn2+2SiO4Orth. mmm (2/m 2/m 2/m)
14.17.4AlleghanyiteMn2+5(SiO4)2(OH)2Mon. 2/m : P21/b
14.17.5Ribbeite(Mn2+,Mg)5(SiO4)2(OH)2Orth.
14.17.6LeucophoeniciteMn2+7(SiO4)3(OH)2Mon. 2/m : P21/b
14.17.7JerrygibbsiteMn2+9(SiO4)4(OH)2Orth. mmm (2/m 2/m 2/m) : Pbcn
14.17.8BementiteMn7Si6O15(OH)8Mon.
14.17.9Parsettensite(K,Na,Ca)7.5(Mn,Mg)49Si72O168(OH)50 · nH2OMon. 2/m : B2/m
14.17.10YofortieriteMn5Si8O20(OH)2 · 8-9H2OMon. 2/m : B2/m

Other InformationHide

Notes:
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 BrauniteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
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.
de Villiers, P.R. & Herbstein, F.H. (1967): Distinction between two members of the braunite group, American Mineralogist 52, 20-30.
De Villiers, J.P.R. (1975): The crystal structure of braunite with reference to its solid solution behaviour. Am. Mineral., 60, 1098-1104.
Moore, P.B., Araki, T. (1976): Braunite: its structure and relationship to bixbyite, and some insights on the genealogy of fluorite derivative structures. American Mineralogist 61, 1226-1240.
de Villiers, J.P.R. (1980): The crystal structure of braunite II and its relation to bixbyite and braunite. American Mineralogist 65, 756-765.
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]
Marescotti, P., Frezzotti, M.L. (2000): Alteration of braunite ores from Eastern Ligeria (Italy) during syntectonic veining processes: mineralogy and fluid inclusions. European Journal of Mineralogy 12, 341-356.
Bevan, D.J.M. & Martin, R.L. (2008): 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.

Internet Links for BrauniteHide

Localities for BrauniteHide

This 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.

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