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Foordite

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Manono, Katanga (Shaba), Democratic Republic of Congo (Zaïre)
© Thomas Witzke

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Formula:
(Sn,Pb)(Nb,Ta)
 
2
O
 
6
System:MonoclinicColour:Dark brown, Yellowish ...
Hardness:6
Name:
Named by Petr Cerny, Andre M. Fransolet, T. Scott Ercit, and R. Chapman in 1988 in honor of Eugene Edward Foord [November 20, 1946 - January 8, 1998 Golden, Colorado, USA], mineralogist of the U. S. Geological Survey and specialist in granite pegmatite research.
Isostructural with:Thoreaulite


Dark brown to bronzey masses.

Classification of Foordite

IMA status:Approved
Strunz 8th edition ID:4/D.29-10
Nickel-Strunz 10th (pending) edition ID:4.DG.15

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
G : With large (+- medium-sized) cations; chains of edge-sharing octahedra
Dana 8th edition ID:8.3.10.2

8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
Hey's CIM Ref.:18.1.23

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

Type Locality:Lutsiro, Sebeya river, Kabaya District, Rwanda
Year of Discovery:1988
Geological Setting of type material:Found as small masses and pebbles in alluvium, presumably derived from a granite pegmatite.

Physical Properties of Foordite

Lustre:Adamantine, Sub-Adamantine, Dull
Diaphaneity (Transparency):Translucent
Comment:Dull on eroded surfaces
Colour:Dark brown, Yellowish brown, olive brown.
Streak:Yellowish white
Hardness (Mohs):6
Tenacity:Brittle
Cleavage:Perfect
{100}, also {011} poor
Fracture:Irregular/Uneven
Density (measured):6.73 g/cm3
Density (calculated):6.66 g/cm3

Crystallography of Foordite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:B2/b {B1 1 2/b} {C2/c} {C1 2/c 1}
Cell Parameters:a = 17.09Å, b = 4.87Å, c = 5.55Å
β = 90.85°
Ratio:a:b:c = 3.509 : 1 : 1.14
Unit Cell Volume:V 461.87 ų (Calculated from Unit Cell)
Comment:C2/c
X-Ray Powder Diffraction:
d-spacingIntensity
3.59 (40)
3.10 (50)
3.07 (50)
2.85 (100)
2.78 (20)
1.853 (30)
1.694 (50)
Comments:45-1350

Optical Data of Foordite

Type:Biaxial (+)
Dispersion:strong

Chemical Properties of Foordite

Formula:
(Sn,Pb)(Nb,Ta)
 
2
O
 
6
Essential elements:Nb, O, Sn
All elements listed in formula:Nb, O, Pb, Sn, Ta
Common Impurities:Pb

Relationship of Foordite to other Species

Series:Forms a series with Thoreaulite (see here)
Related Minerals - Nickel-Strunz Grouping):

- +
4.DG.05Euxenite-(Y)
(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)
 
2
O
 
6
4.DG.05Fersmite
(Ca,Ce,Na)(Nb,Ta,Ti)
 
2
(O,OH,F)
 
6
4.DG.05Kobeite-(Y)
(Y,Zr)
 
2
(Ti,Fe
3+
 
)
 
2
(O,OH)
 
7
4.DG.05Loranskite-(Y)
(Y,Ce,Ca)ZrTaO
 
6
 (?)
4.DG.05Polycrase-(Y)
(Y,U)(Ti,Nb)
 
2
O
 
6
4.DG.05Tanteuxenite-(Y)
(Y,Ce,Ca)(Ta,Nb,Ti)
 
2
(O,OH)
 
6
4.DG.05Uranopolycrase
(U
4+
 
,Y)(Ti,Nb)
 
2
O
 
6
4.DG.05Yttrocrasite-(Y)
(Y,Th,Ca,U)(Ti,Fe)
 
2
(O,OH)
 
6
4.DG.10β-Fergusonite-(Y)
YNbO
 
4
4.DG.10β-Fergusonite-(Nd)
(Nd,Ce)NbO
 
4
4.DG.10β-Fergusonite-(Ce)
(Ce,La,Nd)NbO
 
4
4.DG.10Yttrotantalite-(Y)
(Y,Ca,U
4+
 
,Fe
2+
 
)
 
2
(Ta,Nb)
 
2
O
 
8
4.DG.10Beta-Fergusonite-(Nd)
4.DG.15Thoreaulite
SnTa
 
2
O
 
6
4.DG.20Raspite
PbWO
 
4
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
18.1.15Bariomicrolite
Ba(Ta,Nb)
 
2
(O,OH)
 
7
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
18.1.24Changbaiite
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 Foordite

Synonyms:
IMA1984-070
Other Languages:
German:Foordit
Russian:Фурдит
Spanish:Foordita

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 Foordite

Reference List:American Mineralogist: 75: 707.

Canadian Mineralogist: 26: 899-903.

Internet Links for Foordite

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  • Raman and XRD data at RRUFF project
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    Localities for Foordite

    Hide Locality List
    The 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. ? 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.
    Democratic Republic of Congo (Zaïre)
     
    • Katanga (Shaba)
    		T. Witzke, unpublished microprobe analysis
    • Kivu
      • Punia
    		Kristiansen, R. (2001): Sjeldne tantalniobater fra Sentral-Afrika. eksotiske minerallokaliteter II (Exotic mineral-locations II). STEIN 28 (2): 21-28
    Kristiansen, R. (2001): Sjeldne tantalniobater fra Sentral-Afrika. eksotiske minerallokaliteter II (Exotic mineral-locations II). STEIN 28 (2): 21-28
    Rwanda
     
    • Kabaya District
      • Sebeya river
    		Can. Min. (1988) 26, 889; Am. Min. (1990) 75, 707
    Mineral and/or Locality
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