Allanite-(Y) (original) (raw)
A valid IMA mineral species - grandfathered
About Allanite-(Y)Hide
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Formula:
(CaY)(AlAlFe2+)O[Si2O7][SiO4](OH)
Often slightly radioactive due to minor U and/or Th contents; therefore often metamict.
Lustre:
Sub-Vitreous, Resinous, Waxy, Greasy
Specific Gravity:
3.5 - 4.2
Crystal System:
Monoclinic
Name:
Re-named, but not described, in 1966 by Alfred Abraham Levinson using what is now called the Levinson Rule whereby REE-dominant minerals are named by their root mineral name plus chemical suffixes. Allanite was named in 1810 by Thomas Thomson for Thomas Allan (1777, Edinburgh, Scotland - 1833, Morpeth, Northumberland, England), Scottish banker and mineralogist, who first observed "allanite". The -(Y) suffix was later added by Levinson (1966) to designate the Y-dominant member of the allanite group.
Allanite-(Y) is a member of the allanite group in the epidote supergroup. The key sites in the epidote supergroup minerals are: A1 = M2+, A2 = M3+, M1 = M3+, M2 = M3+, M3 = M2+, O4 = O2-, O10 = (OH)- (Armbruster et al., 2006). Some unnamed species are, however, thought to be dominantly oxidised, with M3 = M3+, balanced by O replacing OH.
Allanite-(Y) has the following dominant cations in these sites:
A1=Ca
A2=Y
M1=Al
M2=Al
M3=Fe2+
It is the only mineral in the epidote supergroup with Y dominance in the A2 site.
Fleischer (1985) has studied analyses of 506 allanites and presents the average content of each of the REE elements (including Y) in various rock types:
| Average REE content in % of total REE content in allanites sorted by rock type | ||||||
|---|---|---|---|---|---|---|
| REE | granite pegmatite | granite | granodiorite | carbonatites | alkaline rocks | alkaline pegmatites |
| %La | 22.2 | 25.3 | 29.3 | 32.4 | 33.3 | 34.9 |
| %Ce | 43.2 | 48.1 | 48.4 | 49.5 | 49.6 | 50.8 |
| %Pr | 5.7 | 5.0 | 4.3 | 4.1 | 4.3 | 3.8 |
| %Nd | 15.9 | 15.4 | 13.5 | 12.1 | 11.1 | 9.1 |
| %Sm | 4.1 | 2.4 | 1.8 | 0.9 | 0.7 | 0.6 |
| %Eu | 0.2 | 0.1 | - | 0.1 | - | - |
| %Gd | 3.8 | 1.3 | 2.0 | 0.3 | 0.2 | 0.3 |
| %Tb | 0.4 | 0.1 | 0.1 | - | - | - |
| %Dy | 2.1 | 1.2 | 0.3 | 0.3 | 0.4 | 0.2 |
| %Ho | 0.3 | 0.3 | - | - | - | 0.1 |
| %Er | 0.9 | 0.3 | 0.3 | 0.1 | 0.1 | 0.1 |
| %Tm | 0.1 | - | - | - | - | - |
| %Yb | 0.9 | 0.4 | 0.1 | 0.2 | 0.2 | 0.1 |
| %Lu | 0.2 | 0.1 | - | - | - | - |
| %Y/(Y+Ln) | 9.6 | 6.8 | 2.2 | - | 0.3 | 1.1 |
| Number of samples analysed | 114 | 139 | 29 | 11 | 13 | 24 |
The Y content in allanites is generally much lower than Ce, La, and Nd. Y-dominant allanite is therefore normally confined to patches or zones within other allanite group minerals or as alteration products of other Y-bearing minerals. Allanite-(Y) is usually black and massive. It is resinous when fresh, but frequently dulled by hydrothermal alteration or weathering.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:127:2
66cbd17d-4b16-466a-b33d-32f6789496bb
IMA Classification of Allanite-(Y)Hide
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Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
CaY(Al2Fe2+)[Si2O7][SiO4]O(OH)
Classification of Allanite-(Y)Hide
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9.BG.05b
9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in octahedral [6] and greater coordination
58.2.1a.3
58 : SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
2 : Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [6] and higher coordination; single and double groups (n = 1, 2)
16.13.4
16 : Silicates Containing Aluminum and other Metals
13 : Aluminosilicates of the rare earths
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Aln-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 Allanite-(Y)Hide
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Sub-Vitreous, Resinous, Waxy, Greasy
Comment:
May be dull due to alteration
Comment:
May be softer due to alteration
Cleavage:
Imperfect/Fair
{001} imperfect, {100} and {110} both poor
Fracture:
Conchoidal, Sub-Conchoidal
Density:
3.5 - 4.2 g/cm3 (Measured)
Comment:
Variable due to alteration
Optical Data of Allanite-(Y)Hide
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RI values:
_n_α = 1.715 - 1.791 _n_β = 1.718 - 1.815 _n_γ = 1.733 - 1.822
2V:
Measured: 40° to 80°, Calculated: 50° to 56°
δ = 0.018 - 0.031
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Dispersion:
distinct to strong
Optical Extinction:
Y=b, OAP || (010)
Chemistry of Allanite-(Y)Hide
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Mindat Formula:
(CaY)(AlAlFe2+)O[Si2O7][SiO4](OH)
Often slightly radioactive due to minor U and/or Th contents; therefore often metamict.
Crystallography of Allanite-(Y)Hide
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Crystal System:
Monoclinic
Morphology:
Usually massive, rarely found in euhedral crystals. Tabular to prismatic crystals typical of allanite sub-group, rarely as rod-like crystals in sprays.
Comment:
Unit cell dimensions unavailable, but should be near allanite-(Ce)
X-Ray Powder DiffractionHide
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Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| Data not available Å | ( |
Comments:
d-values should be similar to allanite sub-group. Unit cell has typical epidote pseudocell (2a, b, 2c)
Geological EnvironmentHide
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Synonyms of Allanite-(Y)Hide
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Other Language Names for Allanite-(Y)Hide
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Relationship of Allanite-(Y) to other SpeciesHide
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Other Members of this group:
Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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Other InformationHide
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Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Allanite-(Y)Hide
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References for Allanite-(Y)Hide
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Reference List:
Armbruster, Thomas, Bonazzi, Paola, Akasaka, Masahide, Bermanec, Vladimir, Chopin, Christian, Gieré, Reto, Heuss-Assbichler, Soraya, Liebscher, Axel, Menchetti, Silvio, Pan, Yuanming, Pasero, Marco (2006) Recommended nomenclature of epidote-group minerals. European Journal of Mineralogy, 18 (5) 551-567 doi:10.1127/0935-1221/2006/0018-0551
Localities for Allanite-(Y)Hide
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This 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.
Locality ListHide
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- 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.