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Pyrochlore

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Orberg Quarry, Orberg Mt. - Badberg Mt. area, Schelingen, Kaiserstuhl, Baden-Württemberg, Germany

Show Pyrochlore Photos (123)
Formula:
(Ca,Na)
 
2
Nb
 
2
O
 
6
(OH,F)
System:IsometricColour:Brown, yellow-brown, ...
Hardness:5 - 5½
Name:From the Greek πΰρ, fire, and χλωρός, green in allusion to the fact that the mineral usually turns green on ignition.
Isostructural with:Roméite


Pyrochlore Group. Pyrochlore Subgroup. Microlite-Pyrochlore Series. The niobium analogue of Microlite. The crystal structure is closely related to that of Pittongite.

Classification of Pyrochlore

IMA status:Approved
Strunz 8th edition ID:4/C.17-10
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:8.2.1.1

8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
2 : A2B2O6(O,OH,F)
Hey's CIM Ref.:18.2.8

18 : Niobates and Tantalates
2 : Niobates and tantalates containing rare earths but not U
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Type Occurrence of Pyrochlore

Type Locality:Stavern (Fredriksvärn), Larvik, Vestfold, Norway
Year of Discovery:1826

Occurrences of Pyrochlore

Geological Setting:Pegmatites in nepheline syenites, granitic pegmatites and greisens, carbonatites.

Physical Properties of Pyrochlore

Lustre:Vitreous, Resinous
Diaphaneity (Transparency):Transparent
Colour:Brown, yellow-brown, reddish brown, orange, black
Streak:Light brown, yellow-brown
Hardness (Mohs):5 - 5½
Hardness (Vickers):VHN100=542 - 665 kg/mm2
Tenacity:Brittle
Cleavage:Distinct/Good
Octahedral {111} (may be a parting), sometimes distinct but usually not distinguishable.
Fracture:Irregular/Uneven, Splintery, Sub-Conchoidal
Density (measured):4.45 - 4.9 g/cm3
Density (calculated):4.33 g/cm3
Comment:Density increases with uranium content.

Crystallography of Pyrochlore

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fd3m {F41/d 3 2/m}
Cell Parameters:a = 10.41(6) Å
Unit Cell Volume:V 1,128.11 ų (Calculated from Unit Cell)
Z:8
Morphology:Crystals octahedral, often with subordinate {011}, {113} or {001}. Irregular masses and embedded grains.
Twinning:Twin plane {111} (spinel law twins), rare.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Chemical Properties of Pyrochlore

Formula:
(Ca,Na)
 
2
Nb
 
2
O
 
6
(OH,F)
Essential elements:Ca, H, Nb, O
All elements listed in formula:Ca, F, H, Na, Nb, O
Common Impurities:Fe,Mg,Mn,U,Ta,Ti

Relationship of Pyrochlore to other Species

Series:Forms a series with Microlite (see here)
Member of Group:
Pyrochlore Group:
Pyrochlore Subgroup:
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.15Bariomicrolite
Ba(Ta,Nb)
 
2
(O,OH)
 
7
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.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:

- +
18.2.1Fergusonite-(Y)
YNbO
 
4
18.2.2β-Fergusonite-(Y)
YNbO
 
4
18.2.3Fergusonite-(Ce)
(Ce,La,Nd)NbO
 
4
18.2.4β-Fergusonite-(Ce)
(Ce,La,Nd)NbO
 
4
18.2.5Fergusonite-(Nd)
(Nd,Ce)(Nb,Ti)O
 
4
18.2.6β-Fergusonite-(Nd)
(Nd,Ce)NbO
 
4
18.2.7Formanite-(Y)
YTaO
 
4
18.2.9Ceriopyrochlore-(Ce)
(Ce,Ca,Y)
 
2
(Nb,Ta)
 
2
O
 
6
(OH,F)
18.2.10Strontiopyrochlore
(Sr,Ce,Ca)
 
2-x
(Nb,Fe)
 
2
(O,OH)
 
7
18.2.11Loparite-(Ce)
(Na,Ce,Ca,Sr,Th)(Ti,Nb,Fe)O
 
3
18.2.12Fersmite
(Ca,Ce,Na)(Nb,Ta,Ti)
 
2
(O,OH,F)
 
6
18.2.13Aeschynite-(Ce)
(Ce,Ca,Fe,Th)(Ti,Nb)
 
2
(O,OH)
 
6
18.2.14Aeschynite-(Nd)
(Nd,Ce,Ca)(Ti,Nb)
 
2
(O,OH)
 
6
18.2.15Aeschynite-(Y)
(Y,Ca,Fe,Th)(Ti,Nb)
 
2
(O,OH)
 
6
18.2.16Nioboaeschynite-(Ce)
(Ce,Ca,Th)(Nb,Ti)
 
2
(O,OH)
 
6
18.2.17Nioboaeschynite-(Nd)
(Nd,Ce,Ca,Th)(Nb,Ti,Fe,Ta)
 
2
(O,OH)
 
6
18.2.18Tantalaeschynite-(Y)
(Y,Ce,Ca)(Ta,Ti,Nb)
 
2
O
 
6
18.2.19Vigezzite
(Ca,Ce)(Nb,Ti)
 
2
O
 
6
18.2.20Murataite-(Y)
(Y,Na)
 
6
Zn(Zn,Fe
3+
 
)
 
4
(Ti,Nb,Na)
 
12
O
 
29
(O,F,OH)
 
10
F
 
4

Other Names for Pyrochlore

Synonyms:
Azor-PhyrriteAzor-pyrrhiteColumbomicroliteEndeioliteFluochlor
HydrochlorKoppiteNiobpyrochlorPyrochlor
Other Languages:
German:Azor-Phyrrit
Azor-pyrrhit
Columbomicrolit
Columbomikrolith
Koppit
Pyrrhit
Russian:Пирохлор
Spanish:Columbomicrolita
Koppita
Varieties:
Thorian PyrochloreZirconian Pyrochlore

Other Information

Health Warning:May be radioactive.

References for Pyrochlore

Reference List:Wöhler (1826), Ann. Pys.: 7: 417.

Rose (1840), Ann. Phys.: 48: 562 (as Pyrrhit).

Knop (1875), Jb. Min.: 67.

Allen (1877), American Journal of Science: 14: 128 (as Hatchettolite).

Smith (1877), American Journal of Science: 13: 365 (as Hatchettolite).

Hubbard (1886), Verh. natur-hist. Ver. preuss. Rheinland, Sitzber.: 43: 217 (as Azor-pyrrhit).

Holmqist (1896), Geological Institute Upsala, Bulletin: 3: 181 (as uranpyrochlore).

Flink (1898), Meddelelser om Grønland: 14: 234 (as chalcolamprite).

Flink (1901), Meddelelser om Grønland: 24: 166 (as Endeiolite).

Gaertner (1930), Jb. Min., Beil.-Bd.: 61: 1.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 748-756.

Hogarth, D.D. (1961) A study of pyrochlore and betafite. Canadian Mineralogist: 6: 610-633.

American Mineralogist (1977): 62: 403-410.

Hogarth, D.D. (1989) Pyrochlore, apatite and amphibole: distinctive minerals in carbonatite. In K. Bell, Ed., Carbonatites: Genesis and Evolution: 105-148. Unwin Hyman Ltd., London.

Anthony, J.W., Bideaux, R.A., Bladh, K.W., and Nichols, M.C. (1997) Handbook of Mineralogy, Volume III. Halides, Hydroxides, Oxides. Mineral Data Publishing, Tucson, AZ, 628pp.: 457.

Bonazzi, P., Bindi, L., Zoppi, M., Capitani, G.C., and Olmi, F. (2006) Single-crystal diffraction and transmission electron microscopy studies of "silicified" pyrochlore from Narssârssuk, Julianehaab district, Greenland. American Mineralogist: 91: 794-801.

Birch, W.D., Grey, I.E., Mills, S.J., Bougerol, C., Pring, A., Ansermet, S. (2007): Pittongite, a new secondary tungstate from Pittong, Victoria, Australia. Canadian Mineralogist, 45, 857-864.

Internet Links for Pyrochlore

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