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Polycrase-(Y)

Big Photo

Baveno, Verbano-Cusio-Ossola Province, Piedmont, Italy
© Stephan Wolfsried

Show Polycrase-(Y) Photos (36)
Formula:
(Y,U)(Ti,Nb)
 
2
O
 
6
System:AmorphousColour:Black
Hardness:5 - 6
Name:From the Greek πολύς, many, and κράσις, mixture.


Metamict (X-ray amorphous) mineral that is mainly found in pegmatites.
U-dominant analogue is uranopolycrase.

May be confused with aeschynite-(Y), which has a similar composition.

Classification of Polycrase-(Y)

IMA status:Approved
Strunz 8th edition ID:4/D.19-10
Nickel-Strunz 10th (pending) edition ID:4.DG.05

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:8.3.8.1

8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
Hey's CIM Ref.:18.4.8

18 : Niobates and Tantalates
4 : Niobates and tantalates containing both U and rare earths
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Type Occurrence of Polycrase-(Y)

Type Locality:Rasvåg feldspar quarry, Hidra (Hitterø), Flekkefjord, Vest-Agder, Norway

Physical Properties of Polycrase-(Y)

Lustre:Vitreous, Greasy, Sub-Metallic
Colour:Black
Streak:Yellowish, grayish, reddish brown
Hardness (Mohs):5 - 6
Fracture:Conchoidal, Sub-Conchoidal
Density (measured):4.9 - 5.1 g/cm3

Crystallography of Polycrase-(Y)

Crystal System:Amorphous
Morphology:Stout prismatic [001], sometimes flattened {010}. The faces are striated parallel to their intersection with {010}. Often in parallel or subparallel and slightly radial aggregates of crystals. Massive.
Twinning:1. On {201}, common. The twins are flattened {010} and striated [001] 2. Possibly on {101}, rare. 3. Possibly on {013}.
Comment:Metamict.
Crystal Atlas:
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Polycrase-(Y) no.1 - Goldschmidt (1913-1926)
Polycrase-(Y) no.7 - Goldschmidt (1913-1926)

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Optical Data of Polycrase-(Y)

Type:Isotropic

Chemical Properties of Polycrase-(Y)

Formula:
(Y,U)(Ti,Nb)
 
2
O
 
6
Essential elements:O, Ti, Y
All elements listed in formula:Nb, O, Ti, U, Y
Common Impurities:Ca,Ce,U,Th,Ta

Relationship of Polycrase-(Y) to other Species

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.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.15Foordite
(Sn,Pb)(Nb,Ta)
 
2
O
 
6
4.DG.15Thoreaulite
SnTa
 
2
O
 
6
4.DG.20Raspite
PbWO
 
4
Related Minerals - Hey's Index Grouping:

- +
18.4.1Uranpyrochlore
(U,Ca,Ce)
 
2
(Nb,Ta)
 
2
O
 
6
(OH,F)
18.4.2Yttrocolumbite-(Y)
Y(U
4+
 
,Fe
2+
 
)Nb
 
2
O
 
8
18.4.3Yttrotantalite-(Y)
(Y,Ca,U
4+
 
,Fe
2+
 
)
 
2
(Ta,Nb)
 
2
O
 
8
18.4.4Ishikawaite
U
4+
 
Fe
2+
 
Nb
 
2
O
 
8
18.4.5Euxenite-(Y)
(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)
 
2
O
 
6
18.4.6Tanteuxenite-(Y)
(Y,Ce,Ca)(Ta,Nb,Ti)
 
2
(O,OH)
 
6
18.4.7Kobeite-(Y)
(Y,Zr)
 
2
(Ti,Fe
3+
 
)
 
2
(O,OH)
 
7
18.4.9Yttropyrochlore-(Y)
(Y,Ca,U)
 
1-2
(Nb,Ta,Ti)
 
2
(O,OH)
 
7
18.4.10Calciobetafite
(Ca,RE,Th,U)
 
2
(Nb,Ta,Ti)
 
2
O
 
7
18.4.11Yttrobetafite-(Y)
(Y,U,Ce)
 
2
(Ti,Nb,Ta)
 
2
O
 
6
OH
18.4.12Samarskite-(Y)
(Y,Fe
3+
 
,Fe
2+
 
,U,Th,Ca)
 
2
(Nb,Ta)
 
2
O
 
8

Other Names for Polycrase-(Y)

Synonyms:
PolycrasePolycrasite
Other Languages:
German:Polycrasit
Polykras
Russian:Поликраз-(Y)
Spanish:Polycrasita
Ukrainian:Полікраз

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 Polycrase-(Y)

Reference List:Scheerer (1844), Ann. Phys.: 62: 430.

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: 787-792.

Neues Jahrbuch für Mineralogie, Monatshefte (1999): 1.

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    Localities for Polycrase-(Y)

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