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Bariomicrolite

Formula:
Ba(Ta,Nb)
 
2
(O,OH)
 
7
System:IsometricColour:Yellowish to orangish
Hardness:4½ - 5
Name:Assigned by the IMA Committee on pyrochlore nomenclature for the predominant barium content and relation to microlite in the pyrochlore group.


Pyrochlore Group. Microlite Subgroup. The barium analogue of the members of the Microlite Subgroup.

Classification of Bariomicrolite

IMA status:Approved
Strunz 8th edition ID:4/C.18-40
Nickel-Strunz 10th (pending) edition ID:4.DH.15

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
H : With large (+- medium-sized) cations; sheets of edge-sharing octahedra
Dana 8th edition ID:8.2.2.2

8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
2 : A2B2O6(O,OH,F)
Hey's CIM Ref.:18.1.15

18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
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Type Occurrence of Bariomicrolite

Type Locality:Chi-Chico, São João del Rei, Mortes valley, Minas Gerais, Southeast Region, Brazil
General Appearance of Type Material:Intergrowths with microlite, may be partially metamict
Geological Setting of type material:Alluvial concentrates derived from a pegmatite
Associated Minerals at type locality:
TantaliteQuartzMicroliteFeldspar GroupCassiterite

Physical Properties of Bariomicrolite

Lustre:Resinous, Dull
Diaphaneity (Transparency):Opaque
Colour:Yellowish to orangish
Hardness (Mohs):4½ - 5
Hardness (Vickers):VHN100=485 - 498
Tenacity:Brittle
Fracture:Irregular/Uneven
Density (measured):5.68 - 5.8 g/cm3
Density (calculated):5.51 g/cm3

Crystallography of Bariomicrolite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fd3m {F41/d 3 2/m}
Cell Parameters:a = 10.57Å
Unit Cell Volume:V 1,180.93 ų (Calculated from Unit Cell)
Z:8
Morphology:Intergrowths with microlite
X-Ray Powder Diffraction:
d-spacingIntensity
3.034 (100)
6.04 (80)
3.18 (65)
2.631 (60)
1.865 (60)
1.591 (45)
Comments:Recorded on type material

Optical Data of Bariomicrolite

Type:Isotropic

Chemical Properties of Bariomicrolite

Formula:
Ba(Ta,Nb)
 
2
(O,OH)
 
7
Essential elements:Ba, O, Ta
All elements listed in formula:Ba, H, Nb, O, Ta
Analytical Data:Analysis of type material; empirical formula calculated after deduction of microlite (3.68 wt.-%), tantalite (0.26 wt.-%), cassiterite (0.12 wt.-%), quartz and feldspar, with Tl considered a contaminant introduced during the separation
U3O8 (1.68)
Ta2O5 (71.59)
Nb2O5 (5.87)
SiO2 (1.2)
TiO2 (1.21)
ThO2 (0.19)
SnO2 (2.05)
Al2O3 (0.42)
As2O3 (0.12)
Sb2O3 (0.01)
Bi2O3 (0.03)
Ce2O3 (0.45)
FeO (0.93)
MnO (0.09)
CuO (0.06)
PbO (0.90)
CaO (0.47)
SrO (0.09)
BaO (4.85)
Ag2O (0.01)
Tl2O (1.56)
H2O (6.9)

sum 100.68 wt.-%
Empirical Formula:
(Ba,Fe,U,···)
 
=0.31
(Ta,Nb,Ti,Sn)
 
=2.00
O
 
5.32
(H
 
2
O)
 
2

Relationship of Bariomicrolite to other Species

Member of Group:
Microlite Subgroup:
Pyrochlore Group:
Related Minerals - Nickel-Strunz Grouping):

- +
4.DH.05Brannerite
(U
4+
 
,Ca)(Ti,Fe
3+
 
)
 
2
O
 
6
4.DH.05Orthobrannerite
U
4+
 
U
6+
 
Ti
 
4
O
 
12
(OH)
 
2
4.DH.05Thorutite
(Th,U,Ca)Ti
 
2
(O,OH)
 
6
4.DH.10Kassite
CaTi
 
2
O
 
4
(OH)
 
2
4.DH.10Lucasite-(Ce)
CeTi
 
2
(O,OH)
 
6
4.DH.15Alumotungstite
(W,Al)(O,OH)
 
3
4.DH.15Bariopyrochlore
(Ba,Sr)
 
2-x
(Nb,Ti)
 
2
(O,OH)
 
7
4.DH.15Betafite
(Ca,U)
 
2
(Ti,Nb)
 
2
O
 
6
(OH)
4.DH.15Bismutomicrolite
(Bi,Ca)(Ta,Nb)
 
2
O
 
6
(OH)
4.DH.15Calciobetafite
(Ca,RE,Th,U)
 
2
(Nb,Ta,Ti)
 
2
O
 
7
4.DH.15Ceriopyrochlore-(Ce)
(Ce,Ca,Y)
 
2
(Nb,Ta)
 
2
O
 
6
(OH,F)
4.DH.15Cesstibtantite
(Cs,Na)SbTa
 
4
O
 
12
4.DH.15Ferritungstite
(W,Fe
3+
 
)(O,OH)
 
3
4.DH.15Jixianite
Pb(W,Fe
3+
 
)
 
2
(O,OH)
 
7
4.DH.15Kalipyrochlore
(K,Sr)
 
2-x
Nb
 
2
O
 
6
(O,OH)·nH
 
2
O
4.DH.15Microlite
(Ca,Na)
 
2
Ta
 
2
O
 
6
(O,OH,F)
4.DH.15Natrobistantite
(Na,Cs)Bi(Ta,Nb,Sb)
 
4
O
 
12
4.DH.15Plumbopyrochlore
(Pb,Ca,Y,U)
 
2-x
(Nb,Ta,Ti)
 
2
O
 
6
(OH,O)
4.DH.15Plumbomicrolite
(Pb,Ca,U)
 
2-x
(Ta,Nb,Sn)
 
2
O
 
6
(O,[])
4.DH.15Plumbobetafite
(Pb,U,Ca)(Ti,Nb)
 
2
O
 
6
(OH,F)
4.DH.15Pyrochlore
(Ca,Na)
 
2
Nb
 
2
O
 
6
(OH,F)
4.DH.15Stibiomicrolite
(Sb,Ca,Na)
 
2
(Ta,Nb)
 
2
O
 
7
4.DH.15Strontiopyrochlore
(Sr,Ce,Ca)
 
2-x
(Nb,Fe)
 
2
(O,OH)
 
7
4.DH.15Stannomicrolite
(Sn,Fe,Mn)
 
2
(Ta,Nb,Sn)
 
2
(O,OH)
 
7
4.DH.15Stibiobetafite
(Sb,Ca)
 
2
(Ti,Nb,Ta)
 
2
(O,OH)
 
7
4.DH.15Uranmicrolite
(U,Ca,Ce)
 
2
(Ta,Nb)
 
2
O
 
6
(OH,F)
4.DH.15Uranpyrochlore
(U,Ca,Ce)
 
2
(Nb,Ta)
 
2
O
 
6
(OH,F)
4.DH.15Yttrobetafite-(Y)
(Y,U,Ce)
 
2
(Ti,Nb,Ta)
 
2
O
 
6
OH
4.DH.15Yttropyrochlore-(Y)
(Y,Ca,U)
 
1-2
(Nb,Ta,Ti)
 
2
(O,OH)
 
7
4.DH.15Fluornatromicrolite
(Na,Ca,Bi)
 
2
Ta
 
2
O
 
6
F
4.DH.15Bismutopyrochlore
(Bi,U,Ca,Pb)
 
1+x
(Nb,Ta)
 
2
O
 
6
(OH)·nH
 
2
O
4.DH.15Thorian Pyrochlore
4.DH.15Elsmoreite
WO
 
3
·0.5H
 
2
O
4.DH.20Bismutostibiconite
Bi(Sb
5+
 
,Fe
3+
 
)
 
2
O
 
7
4.DH.20Bindheimite
Pb
 
2
Sb
 
2
O
 
6
(O,OH)
4.DH.20Monimolite
(Pb,Ca,Fe)
 
3
Sb
 
2
O
 
7
4.DH.20Partzite
Cu
 
2
Sb
 
2
(O,OH)
 
7
4.DH.20Roméite
(Ca,Fe,Mn,Na)
 
2
(Sb,Ti)
 
2
O
 
6
(O,OH,F)
4.DH.20Stetefeldtite
Ag
 
2
Sb
 
2
(O,OH)
 
7
4.DH.20Stibiconite
Sb
3+
 
Sb
5+
2
O
 
6
(OH)
4.DH.25Rosiaite
PbSb
5+
2
O
 
6
4.DH.30Zirconolite
CaZrTi
 
2
O
 
7
4.DH.35Liandratite
U(Nb,Ta)
 
2
O
 
8
4.DH.35Petscheckite
UFe(Nb,Ta)
 
2
O
 
8
4.DH.40Ingersonite
Ca
 
3
MnSb
 
4
O
 
14
4.DH.45Pittongite
Na
 
0.22
(W,Fe
3+
 
)(O,OH)
 
3
 · 0.44H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
18.1.1Lithiotantite
Li(Ta,Nb)
 
3
O
 
8
18.1.2Lueshite
NaNbO
 
3
18.1.3Natroniobite
NaNbO
 
3
18.1.4Franconite
Na
 
2
Nb
 
4
O
 
11
·9H
 
2
O
18.1.5Natrotantite
Na
 
2
Ta
 
4
O
 
11
18.1.6Irtyshite
Na
 
2
(Ta,Nb)
 
4
O
 
11
18.1.7Rankamaite
(Na,K,Pb,Li)
 
3
(Ta,Nb,Al)
 
11
(O,OH)
 
30
18.1.8Kalipyrochlore
(K,Sr)
 
2-x
Nb
 
2
O
 
6
(O,OH)·nH
 
2
O
18.1.9Calciotantite
CaTa
 
4
O
 
11
18.1.10Rynersonite
Ca(Ta,Nb)
 
2
O
 
6
18.1.11Microlite
(Ca,Na)
 
2
Ta
 
2
O
 
6
(O,OH,F)
18.1.12Belyankinite
Ca
 
1-2
(Ti,Zr,Nb)
 
5
O
 
12
 · 9H
 
2
O (?)
18.1.13Latrappite
(Ca,Na)(Nb,Ti,Fe)O
 
3
18.1.14Hochelagaite
(Ca,Na,Sr)(Nb,Ti,Si,Al)
 
4
O
 
11
·8H
 
2
O
18.1.16Parabariomicrolite
BaTa
 
4
O
 
10
(OH)
 
2
·2H
 
2
O
18.1.17Bariopyrochlore
(Ba,Sr)
 
2-x
(Nb,Ti)
 
2
(O,OH)
 
7
18.1.18Alumotantite
AlTaO
 
4
18.1.19Simpsonite
Al
 
4
(Ta,Nb)
 
3
O
 
13
(OH,F)
18.1.20Sosedkoite
(K,Na)
 
5
Al
 
2
(Ta,Nb)
 
22
O
 
60
18.1.21Thoreaulite
SnTa
 
2
O
 
6
18.1.22Stannomicrolite
(Sn,Fe,Mn)
 
2
(Ta,Nb,Sn)
 
2
(O,OH)
 
7
18.1.23Foordite
(Sn,Pb)(Nb,Ta)
 
2
O
 
6
18.1.24Changbaiite
PbNb
 
2
O
 
6
18.1.25Plumbopyrochlore
(Pb,Ca,Y,U)
 
2-x
(Nb,Ta,Ti)
 
2
O
 
6
(OH,O)
18.1.26Plumbomicrolite
(Pb,Ca,U)
 
2-x
(Ta,Nb,Sn)
 
2
O
 
6
(O,[])
18.1.27Stibiocolumbite
Sb(Nb,Ta)O
 
4
18.1.28Stibiotantalite
Sb(Ta,Nb)O
 
4
18.1.29Natrobistantite
(Na,Cs)Bi(Ta,Nb,Sb)
 
4
O
 
12
18.1.30Cesplumtantite
(Cs,Na)
 
2
(Pb,Sb
3+
 
)
 
3
Ta
 
8
O
 
24
18.1.31Stibiomicrolite
(Sb,Ca,Na)
 
2
(Ta,Nb)
 
2
O
 
7
18.1.32Cesstibtantite
(Cs,Na)SbTa
 
4
O
 
12
18.1.33 Stibobetafite
(Ca,Sb)
 
2
(Ti,Nb,Ta)
 
2
(O,OH)
 
7
18.1.34Bismutotantalite
Bi(Ta,Nb)O
 
4
18.1.35Bismutomicrolite
(Bi,Ca)(Ta,Nb)
 
2
O
 
6
(OH)
18.1.36Tantalite-(Mn)
MnTa
 
2
O
 
6
18.1.37Gerasimovskite
(Mn,Ca)(Nb,Ti)
 
5
O
 
12
·9H
 
2
O
18.1.38Tapiolite-(Mn)
(Mn,Fe)(Ta,Nb)
 
2
O
 
6
18.1.39Columbite-(Mn)
(Mn,Fe)(Nb,Ta)
 
2
O
 
6
18.1.40Wodginite
Mn(Sn,Ta)Ta
 
2
O
 
8
18.1.41Ixiolite
(Ta,Nb,Sn,Fe,Mn)
 
4
O
 
8
18.1.42Columbite-(Fe)
FeNb
 
2
O
 
6
18.1.43Tantalite-(Fe)
FeTa
 
2
O
 
6
18.1.44Columbite
(Fe,Mn)(Nb,Ta)
 
2
O
 
6
18.1.45Tantalite
(Fe,Mn)(Ta,Nb)
 
2
O
 
6
18.1.46Tapiolite
(Fe,Mn)(Ta,Nb)
 
2
O
 
6
18.1.47Tapiolite-(Fe)
(Fe,Mn)(Ta,Nb)
 
2
O
 
6
18.1.48Columbite-(Mg)
(Mg,Fe,Mn)(Nb,Ta)
 
2
O
 
6
18.1.50Strüverite
(Ti,Ta,Fe)O
 
2
18.1.51 Staringite
(Fe,Mn)
 
x
(Ta,Nb)
 
2x
Sn
 
6-3x
O
 
12

Other Names for Bariomicrolite

Synonyms:
Rijkeboerite
Other Languages:
German:Bariomicrolit
Bariomikrolith
Rijkeboerit
Russian:Бариомикролит
Spanish:Bariomicrolita
Rijkeboerita

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 Bariomicrolite

Reference List:van der Veen, A. H. (1963): A study of pyrochlore. Verhandel. Kon. Nederlands Geol. Mijnbouwkundig Genootschap. Geol. Ser. 22, 188 p. - American Mineralogist (1963), 48, 1415 (abstract).

Hogarth, D. D. (1977): Classification and nomenclature of the pyrochlore group. American Mineralogist 62, 403-410, esp. 406-407.

Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 41.

Internet Links for Bariomicrolite

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    Localities for Bariomicrolite

    (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.
    Brazil
     
    • Southeast Region
      • Minas Gerais
        • Mortes valley
          • São João del Rei
    		Am Min 62 (1977), 403
    Mineral and/or Locality
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