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Aeschynite-(Y)

Discovered in 1966;   IMA status: Valid (IMA approved 1966)

Chemistry

Chemical Formula:

(Y,Ca,Fe)(Ti,Nb)₂(O,OH)₆

Yttrium Calcium Iron Titanium Niobium Oxide Hydroxide

Molecular Weight:

274.97 gm

Composition:

Calcium

4.37 %

Ca

6.12 %

CaO

Yttrium

19.40 %

Y

24.64 %

Y₂O₃

Titanium

30.47 %

Ti

50.84 %

TiO₂

Niobium

8.45 %

Nb

12.08 %

Nb₂O₅

Iron

2.03 %

Fe

2.61 %

FeO

Hydrogen

0.37 %

H

3.28 %

H₂O

Oxygen

34.91 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/D.21-20

Nickel-Strunz 10th Ed. ID:

4.DF.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
F : With large (+- medium-sized) cations; dimers and trimers of edgesharing octahedra

Related to:

Aeschynite Group. The yttrium analogue of Aeschynite-(Ce). Forms two series, with Aeschynite-(Ce) and with Tantalaeschynite-(Y).

Varieties:

Alumolyndochite, Calciolyndochite

Synonyms:

Aeschinite-(Y), Aeschynite-(Yt), Blomstrandine, Blomstrandinite, Eschynite, Priorite, Taiyite

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals, to 10 cm, commonly tabular, less commonly prismatic, also granular.

Twinning:

None

Physical Properties

Cleavage:

Perfect on {100}, {010} and {001}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

4.82 - 4.93 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Magnetic

Optical Properties

Color:

Black, Brownish black, Brown, Brownish Yellow, pale Yellow, Yellow-Orange, pale Greenish Yellow

Transparency:

Opaque to Semi-Transparent

Luster:

Resinous, Waxy, Pearly, Sub-Metallic, Submetallic to Pearly on crystal faces, Resinous to Waxy on fracture surfaces.

Refractive Index:

2.19 - 2.50   Biaxial ( + )

Birefringence:

0.150 - 0.220

Dispersion:

Strong; r > v

Pleochroism:

None

Occurances

Geological Setting:

In granite and granite pegmatites; in ankerite-dolomitic carbonatites; as a detrital mineral in placers.

Common Associations:

Euxenite, Monazite, Xenotime, Allanite, Zircon, Fergusonite, Thorite, Synchysite, Gadolinite, Chernovite, Columbite, Biotite, Muscovite, Titanite, Corundum

Common Impurities:

REE, Sn

Type Locality:

Urstad feldspar quarry, Hidra (Hitterø), Flekkefjord, Vest-Agder, Norway

Year Discovered:

1966

View mineral photos:

Aeschynite-(Y) Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Aeschynite-(Y) is a rare ytrrium REE (rare earth element) mineral that is extremely rare as a gemstone. It is found at several locations around the world but the main source is the type locality; Iveland, Aust-Agder, Norway. It is closely related to Aeschynite-Ce (Cerium) and Aeschynite-Nd (Neodymium), both of which are slightly radioactive.

Aeschynite-(Y) gets its name from the Greek word for shame, in allusion to the fact that early chemists had difficulty with separations of titanium from zirconium in some samples and (Y) for its yttrium content as the dominant rare-earth element.

Rare earth oxides such as Aeschynite form from elements that are often leftover from other minerals. Other rare earth oxides such as Fergusonite-(Ce), Samarskite-(Y) and Euxenite-(Y) have very similar properties to Aeschynite and are often associated with each other and are difficult to distinguish from each other. Even the common oxide, Rutile, is almost indistinguishable from these rare earth oxides without chemical tests when Rutile is found in its massive form.

Aeschynite-(Y) is found at a number of localities around the world including many localities in Norway, including: at Urstad, on Hidra (Hitterö) Island; Sätersdalen; at Kåbuland, Mölland, and Birkeland; near Arendal, Mörefjär, and Salterö; at Frikstad. In Russia, at Miass, in the Ilmen Mountains, Southern Ural Mountains. In Switzerland, from Piz Lucendro, near the St. Gotthard Pass, on Pizzo Rotondo, Val Bedretto, and Val Nalps, Tavetsch, Graub¨unden; and elsewhere. In Italy, on Pizzo Cervandone, Alpe Devero, Val d’Aosta, Piedmont. At Böckstein, near Bad Gestein, Austria. From Tongafeno, Ambedabao, Ambohitromby, near Ambatofotsy, Tomboarivo, and other localities in Madagascar. From the Embabaan district, Swaziland. In the USA at Clora May Mine (Mina Blanca; Clara May Lode), Trout Creek Pass pegmatite District, Buena Vista, Chaffee Co., Colorado. A number of other less-well-defined localities are known.

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