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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, 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
Analyical 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

Related to:
  • Microlite Subgroup
  • Pyrochlore Group
    • Related Minerals - Nickel-Strunz Grouping):
    4.DH.05Brannerite
    (U
    4+
     
    		,Ca)(Ti,Fe
    3+
     
    		)
     
    2
    		O
     
    6
    4.DH.05Orthobrannerite
    UTi
     
    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
    		(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,Y,U,Ca)
     
    2-x
    		Nb
     
    2
    		O
     
    6
    		(OH)
    4.DH.15Plumbomicrolite
    (Pb,Ca,U)
     
    2
    		Ta
     
    2
    		O
     
    6
    		(OH)
    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)
     
    0.66
    		(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,Na,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
    SbSb
     
    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
    		(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,Y,U,Ca)
     
    2-x
    		Nb
     
    2
    		O
     
    6
    		(OH)
    18.1.26Plumbomicrolite
    (Pb,Ca,U)
     
    2
    		Ta
     
    2
    		O
     
    6
    		(OH)
    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
    German names:
    BariomicrolitBariomikrolithRijkeboerit
    Russian names:
    Бариомикролит
    Spanish names:
    BariomicrolitaRijkeboerita

    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
        • São João del Rei
    		Am Min 62 (1977), 403
    Mineral and/or Locality
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