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Braunite-II

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Wessels Mine (Wessel's Mine), Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa
© vasco trancoso

Formula:
CaMn
3+
14
SiO
 
24
System:TetragonalColour:black
Hardness:6
Name:relation to braunite


Braunite group

Classification of Braunite-II

IMA status:Published without Approval
Nickel-Strunz 10th (pending) edition ID:9.AG.05

9 : SILICATES (Germanates)
A : Nesosilicates
G : Nesosilicates with additional anions; cations in > [6] +- [6] coordination
Dana 8th edition ID:7.5.1.3

7 : MULTIPLE OXIDES
5 : (AB)2X3
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Type Occurrence of Braunite-II

Type Locality:Black Rock Mine, Black Rock, Kalahari manganese fields, Northern Cape Province, South Africa

Physical Properties of Braunite-II

Lustre:Sub-Metallic
Colour:black
Comment:yellow-brown in reflected light
Hardness (Mohs):6
Hardness Data:Measured

Crystallography of Braunite-II

Crystal System:Tetragonal
Class (H-M):4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:I41/acd {I41/a 2/c 2/d}
Cell Parameters:a = 9.431Å, c = 37.774Å
Ratio:a:c = 1 : 4.005
Unit Cell Volume:V 3359.76 ų
Z:8
X-Ray Powder Diffraction:
d-spacingIntensity
3.68 (40)
2.72 (100)
2.35 (60)
1.996 (20)
1.666 (90)
1.423 (70)
1.081 (30)

Chemical Properties of Braunite-II

Formula:
CaMn
3+
14
SiO
 
24
All elements listed in formula:Ca, Mn, O, Si

Relationship of Braunite-II to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.AG.05Abswurmbachite
CuMn
3+
6
O
 
8
(SiO
 
4
)
9.AG.05Braunite
Mn
2+
 
Mn
3+
6
[O
 
8
|SiO
 
4
]
9.AG.05Neltnerite
CaMn
3+
6
[O
 
8
|SiO
 
4
]
9.AG.10Långbanite
(Mn
2+
 
,Ca)
 
4
(Mn
3+
 
,Fe
3+
 
)
 
9
Sb
5+
 
[O
 
8
|SiO
 
4
]
 
2
9.AG.15Malayaite
CaSn[O|SiO
 
4
]
9.AG.15Titanite
CaTi[O|SiO
 
4
]
9.AG.15Vanadomalayaite
CaV
4+
 
[O|SiO
 
4
]
9.AG.20Cerite-(Ce)
(Ce,Ca)
 
9
(Fe,Mg)(SiO
 
4
)
 
3
[SiO
 
3
(OH)]
 
4
(OH)
 
3
9.AG.20Cerite-(La)
(La,Ce,Ca)
 
9
(Fe,Ca,Mg)(SiO
 
4
)
 
3
[SiO
 
3
(OH)]
 
4
(OH)
 
3
9.AG.20Aluminocerite-(Ce)
(Ce,La,Ca)
 
9
(Al,Fe
3+
 
)(SiO
 
4
)
 
3
[SiO
 
3
(OH)]
 
4
(OH)
 
3
9.AG.25Trimounsite-(Y)
Y
 
2
Ti
 
2
[O
 
5
|SiO
 
4
]
9.AG.25Yftisite-(Y)
(Y,Dy,Er)
 
4
(Ti,Sn)O(SiO
 
4
)
 
2
(F,OH)
 
6
9.AG.30Sitinakite
KNa
 
2
Ti
 
4
Si
 
2
O
 
13
(OH)·2H
 
2
O
9.AG.35Kittatinnyite
Ca
 
2
Mn
 
2
Mn(SiO
 
4
)
 
2
(OH)
 
4
·9H
 
2
O
9.AG.40aNatisite
Na
 
2
Ti[O|SiO
 
4
]
9.AG.40bParanatisite
Na
 
2
Ti[O|SiO
 
4
]
9.AG.45Törnebohmite-(Ce)
(Ce,La)
 
2
Al(SiO
 
4
)
 
2
OH
9.AG.45Törnebohmite-(La)
(La,Ce)
 
2
Al(SiO
 
4
)
 
2
OH
9.AG.50Kuliokite-(Y)
Y
 
4
Al(SiO
 
4
)
 
2
(OH)
 
2
F
 
5
9.AG.55Chantalite
CaAl
 
2
[(OH)
 
4
|SiO
 
4
]
9.AG.60Mozartite
CaMn
3+
 
[OH|SiO
 
4
]
9.AG.60Vuagnatite
CaAl[OH|SiO
 
4
]
9.AG.65Hatrurite
Ca
 
3
[O|SiO
 
4
]
9.AG.70Jasmundite
Ca
 
11
[O
 
2
|S|(SiO
 
4
)
 
4
]
9.AG.75Afwillite
Ca
 
3
[HSiO
 
4
]
 
2
 · 2H
 
2
O
9.AG.80Bultfonteinite
Ca
 
2
[F|HSiO
 
4
] · H
 
2
O
9.AG.85Zoltaiite
BaV
4+
2
V
3+
12
Si
 
2
O
 
27
9.AG.90Tranquillityite
(Fe
2+
 
,Ca)
 
8
(Zr,Y)
 
2
Ti
 
3
[O
 
4
|SiO
 
4
]
 
3

Other Information

Health Warning: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-II

Reference List:de Villiers, P.R. & F.H. Herbstein, Distinction between two members of the braunite group, American Mineralogist 52, 20(1967)

Moore, P.B. & T. Araki, Braunite: its structure and relationship to bixbyite, and some insights on the geanealogy of fluorite derivative structures, American Mineralogist 61, 1226-1240(1976)

de Villiers, J.P.R., The crystal structure of braunite II and its relation to bixbyite and braunite, American Mineralogist 65, 756(1980)

Baudracco-Gritti, C., Substitution du manganese bivalent par du calcium dans les mineraux du groupe: braunite, neltnerite, braunite II. Bulletin de Mineralogie 108,437(1985) [Amer. Min. 71,1543(1986); abstract and discussion]

de Villiers, J.P. & P.R.Buseck, Stacking variations and nonstoichiometry in the bixbyite-braunite polysomatic mineral group, American Mineralogist 74, 1325-1336(1989)

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)

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    Localities for Braunite-II

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    South Africa
     
    • Northern Cape Province
      • Kalahari manganese fields
        • Black Rock
    		Am. Min. 52,20-30(1967)
    Mineral and/or Locality
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