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Braunite-II

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Formula:
CaMn143+(SiO4)O20
System:
Tetragonal
Colour:
black
Hardness:
6
Name:
For the close relation to braunite.
Braunite group.
Has a doubled cell parameter c by comparison to braunite.

Classification of Braunite-II

Published without Approval
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
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First Recorded Occurrence of Braunite-II

Physical Properties of Braunite-II

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
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 Data:
d-spacingIntensity
3.68 (40)
2.72 (100)
2.35 (60)
1.996 (20)
1.666 (90)
1.423 (70)
1.081 (30)
1.052 (20)

Chemical Properties of Braunite-II

Formula:
CaMn143+(SiO4)O20
Essential elements:
All elements listed in formula:

Relationship of Braunite-II to other Species

9.AG.05AbswurmbachiteCuMn63+(SiO4)O8
9.AG.05BrauniteMn2+Mn63+(SiO4)O8
9.AG.05NeltneriteCaMn63+(SiO4)O8
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

Other Information

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-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)

Internet Links for Braunite-II

Localities for Braunite-II

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
Morocco
 
  • Souss-Massa-Draâ Region
    • Ouarzazate Province
FAVREAU G. & DIETRICH J.E. (2006) Tachgagalt (Maroc), Le Cahier des Micromonteurs, 93, 37-71.
South Africa (FRL)
 
  • Northern Cape Province
    • Kalahari manganese field
      • Black Rock
American Mineralogist (1967): 52, 20-30; Von Bezing, K. L. et al. (1991) The Kalahari manganese field: An Update, Mineralogical Record 22(4) pp 282; Cairncross, B. and Dixon, R., (1995) Minerals of South Africa. The Geological Society of South Africa: pp 190; Cairncross, B., and Beukes, N. J., (2013) The Kalahari Manganese Field, the adventure continues. Struik Nature Publishers, Cape Town, South Africa, pp 156.
      • Hotazel
Cairncross, B., Beukes, N. and Gutzmer, J. (1997): The manganese adventure – the South African manganese fields. Associated Ore & Metal Corporation Limited, Johannesburg, Republic of South Africa, 128 pp.; Beukes, N. J., Burger, A. M., & Gutzmer, J. (1995). Fault-controlled hydrothermal alteration of Palaeoproterozoic manganese ore in Wessels Mine, Kalahari manganese field. South African Journal of Geology, 98(4), 430-451.
      • Kuruman
        • N'Chwaning Mines
Cairncross, B., Beukes, N. and Gutzmer, J. (1997): The manganese adventure – the South African manganese fields. Associated Ore & Metal Corporation Limited, Johannesburg, Republic of South Africa, 236 pp.
Mineral and/or Locality  
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