Euxenite-(Y)
A valid IMA mineral species - grandfathered
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About Euxenite-(Y)
Formula:
(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Usually the sum (Nb+Ta) is close to Ti, in other words (Nb+Ta)/Ti ~ 1.
Synthetic end-member: YTiNbO6
Synthetic end-member: YTiNbO6
Colour:
Black, greenish or brownish tint at times
Lustre:
Vitreous, Greasy, Sub-Metallic
Hardness:
5½ - 6½
Specific Gravity:
5.3 - 5.9
Crystal System:
Orthorhombic
Member of:
Name:
From the Greek εΰζευος, friendly to strangers, hospitale, in allusion to the many rare elements that it contains.
Type Locality:
Isostructural with:
Minerals of the Euxenite group are the most widespread niobates after the columbite group and pyrochlore group.
Polycrase-(Y) was discredited by the CNMNC in 2022 and merged with euxenite-(Y) as they are identical. Both minerals were first described by (Karl Johan August) Theodor Scheerer, a German-Norwegian chemist and mineralogist: "euxenit" in 1840 and "polykras" in 1844. Consequently, the former mineral name has historical priority. See the discussion in http://www.mindat.org/mesg-104-381642.html.
Euxenite-(Y) is typically metamict.
Compare Nioboaeschynite-(Y) which has different space-group symmetry. Compare also Fergusonite-(Y).
An euxenite-(Y)-columbite solid solution is also known.
Polycrase-(Y) was discredited by the CNMNC in 2022 and merged with euxenite-(Y) as they are identical. Both minerals were first described by (Karl Johan August) Theodor Scheerer, a German-Norwegian chemist and mineralogist: "euxenit" in 1840 and "polykras" in 1844. Consequently, the former mineral name has historical priority. See the discussion in http://www.mindat.org/mesg-104-381642.html.
Euxenite-(Y) is typically metamict.
Compare Nioboaeschynite-(Y) which has different space-group symmetry. Compare also Fergusonite-(Y).
An euxenite-(Y)-columbite solid solution is also known.
Unique Identifiers
Mindat ID:
1425
Long-form identifier:
mindat:1:1:1425:6
Similar Names
| Eugenite | A valid IMA mineral species | Ag11Hg2 |
| Euxenite-(Y)-Columbite solid solution | A solid-solution series between two end-member minerals | |
| Yixunite | A valid IMA mineral species | Pt3In |
IMA Classification of Euxenite-(Y)
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Y(Ti4+,Nb5+)2(O,OH)6
Classification of Euxenite-(Y)
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
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
8.3.8.2
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
18.4.5
18 : Niobates and Tantalates
4 : Niobates and tantalates containing both U and rare earths
18 : Niobates and Tantalates
4 : Niobates and tantalates containing both U and rare earths
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Eux-Y | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Euxenite-(Y)
Vitreous, Greasy, Sub-Metallic
Colour:
Black, greenish or brownish tint at times
Comment:
Brown to yellow brown in transmitted light.
Streak:
Yellowish, grayish, reddish brown
Hardness:
5½ - 6½ on Mohs scale
Hardness:
VHN50=633 - 692 kg/mm2 - Vickers
Tenacity:
Brittle
Fracture:
Conchoidal, Sub-Conchoidal
Density:
5.3 - 5.9 g/cm3 (Measured) 5.16 g/cm3 (Calculated)
Optical Data of Euxenite-(Y)
Type:
Isotropic
RI values:
n = 2.06 - 2.24
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Chemistry of Euxenite-(Y)
Mindat Formula:
(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Usually the sum (Nb+Ta) is close to Ti, in other words (Nb+Ta)/Ti ~ 1.
Synthetic end-member: YTiNbO6
Usually the sum (Nb+Ta) is close to Ti, in other words (Nb+Ta)/Ti ~ 1.
Synthetic end-member: YTiNbO6
Element Weights:
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| Nb2O5 | 23.49 % |
| Ta2O5 | 2.55 % |
| TiO2 | 25.64 % |
| SiO2 | 0.47 % |
| SnO2 | 0.12 % |
| UO2 | 7.95 % |
| ThO2 | 2.40 % |
| REE total | 25.77 % |
| Sc2O3 | 0.03 % |
| PbO | 0.12 % |
| Al2O3 | 0.07 % |
| FeO | 0.40 % |
| Fe2O3 | 4.66 % |
| MnO | 0.18 % |
| MgO | 0.08 % |
| CaO | 2.8 % |
| BaO | 0.0014 % |
| SrO | 0.001 % |
| Cr2O3 | 0.001 % |
| CoO | 0.001 % |
| NiO | 0.001 % |
| CuO | 0.001 % |
| H20 | 3.26 % |
| Total: | 99.9964 % |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Kalstadgangen, Lindvikskollen-Kalstadgangen pegmatite, Kragerø, Telemark, Norway | Whetchemical analyses Note: The stannic oxide is contaminated with barium. |
Crystallography of Euxenite-(Y)
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbcn
Setting:
Pbcn
Cell Parameters:
a = 5.5528(6) Å, b = 14.6432(20) Å, c = 5.1953(7) Å
Ratio:
a:b:c = 0.379 : 1 : 0.355
Unit Cell V:
422.43 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Stout prismatic [001]. 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:
Typically metamict; heating at high temperatures will restore crystallinity.
Crystallographic forms of Euxenite-(Y)
Crystal Atlas:
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Euxenite-(Y) no.4 - {010} - Goldschmidt (1913-1926)
Euxenite-(Y) no.5 - {100} - Goldschmidt (1913-1926)
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0010827 | Euxenite-(Y) | Weitzel H, Schrocke H (1980) Kristallstrukturverfeinerungen von euxenit, Y(Nb0.5Ti0.5)2O6, und M-fergusonit, YNbO4 Zeitschrift fur Kristallographie 152 69-82 |  | 1980 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.66 Å | (3) |
| 2.98 Å | (10) |
| 2.43 Å | (3) |
| 1.82 Å | (4) |
| 1.77 Å | (3) |
| 1.72 Å | (4) |
| 1.64 Å | (3) |
| 1.49 Å | (4) |
Comments:
Heated
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 26 : Hadean detrital minerals | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Geological Setting:
Granitic pegmatites. Placer deposits.
Type Occurrence of Euxenite-(Y)
Synonyms of Euxenite-(Y)
Other Language Names for Euxenite-(Y)
Relationship of Euxenite-(Y) to other Species
Member of:
Other Members of Euxenite Group:
| Fersmite | CaNb2O6 | Orth. mmm(2/m2/m2/m) : Pbcn |
| Kobeite-(Y) | (Y,U)(Ti,Nb)2(O,OH)6 (?) | Iso. |
| Loranskite-(Y) | (Y,Ce,Ca)ZrTaO6 (?) | |
| Tanteuxenite-(Y) | Y(Ta,Nb,Ti)2(O,OH)6 | Orth. mmm(2/m2/m2/m) : Pbcn |
| Uranopolycrase | (U4+,Y)(Ti,Nb)2O6 | Orth. mmm(2/m2/m2/m) : Pbcn |
| Yttrocrasite-(Y) | (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 | Amor. |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 28 photos of Euxenite-(Y) associated with Microcline | K(AlSi3O8) |
| 17 photos of Euxenite-(Y) associated with Quartz | SiO2 |
| 16 photos of Euxenite-(Y) associated with Magnetite | Fe2+Fe3+2O4 |
| 15 photos of Euxenite-(Y) associated with Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| 14 photos of Euxenite-(Y) associated with 'Columbite-(Fe)-Columbite-(Mn) Series' | |
| 14 photos of Euxenite-(Y) associated with Albite | Na(AlSi3O8) |
| 13 photos of Euxenite-(Y) associated with Chlorite Group | |
| 12 photos of Euxenite-(Y) associated with Columbite-(Mn) | Mn2+Nb2O6 |
| 11 photos of Euxenite-(Y) associated with Monazite-(Ce) | Ce(PO4) |
| 11 photos of Euxenite-(Y) associated with Feldspar Group |
Related Minerals - Strunz-mindat Grouping
| 4.DG.05 | Fersmite | CaNb2O6 |
| 4.DG.05 | Uranopolycrase | (U4+,Y)(Ti,Nb)2O6 |
| 4.DG.05 | Yttrocrasite-(Y) | (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 |
| 4.DG.05 | Tanteuxenite-(Y) | Y(Ta,Nb,Ti)2(O,OH)6 |
| 4.DG.05 | Loranskite-(Y) | (Y,Ce,Ca)ZrTaO6 (?) |
| 4.DG.05 | Kobeite-(Y) | (Y,U)(Ti,Nb)2(O,OH)6 (?) |
| 4.DG.10 | Yttrotantalite-(Y) | (Y,U,Fe2+)(Ta,Nb)(O,OH)4 |
| 4.DG.10 | Clinofergusonite-(Y) | YNbO4 |
| 4.DG.10 | Clinofergusonite-(Nd) | (Nd,Ce)NbO4 |
| 4.DG.10 | Clinofergusonite-(Ce) | CeNbO4 |
| 4.DG.15 | Foordite | Sn2+Nb2O6 |
| 4.DG.15 | Thoreaulite | Sn2+Ta2O6 |
| 4.DG.20 | Raspite | Pb(WO4) |
Other Information
Health Risks:
May be radioactive.
Internet Links for Euxenite-(Y)
mindat.org URL:
https://www.mindat.org/min-1425.html
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References for Euxenite-(Y)
Reference List:
Scheerer, Th. (1840) Ueber den Euxenit, eine neue Mineralspecies. Annalen der Physik und Chemie, 126. 149-153 doi:10.1002/andp.18401260510
Localities for Euxenite-(Y)
Showing 691 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
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Håverstad, Iveland, Agder, Norway