Xenotime-(Y)
Current inventory: 0 gems
 

  
Xenotime-(Y) is named from the Greek words xenos (κευός) meaning vain and time (τιμή) meaning honor, in allusion to the fact that the yttrium it contained was mistaken for a new element at the time. The suffix -(Y) is due to its yttrium dominance.

Discovered in 1824; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

YPO₄ + REE

Yttrium Phosphate + traces of rare earth elements (REE)

Molecular Weight:

183.88 gm

Composition:

Yttrium

48.35 %

Y

61.40 %

Y₂O₃

Phosphorus

16.84 %

P

38.60 %

P₂O₅

Oxygen

34.80 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/A.14-10

Nickel-Strunz 10th Ed. ID:

8.AD.35

8 : PHOSPHATES, ARSENATES, VANADATES
A : Phosphates, etc. without additional anions, without H₂O
D : With only large cations

Related to:

Xenotime Group. Chernovite-(Y)-Xenotime-(Y) Series. Isostructural with Zircon.

Members of Group:

Xenotime Group: Chernovite-(Y), Pretulite, Wakefieldite-(Ce), Wakefieldite-(La), Wakefieldite-(Nd), Wakefieldite-(Y), Xenotime-(Yb)

Varieties:

Chrysanthemum Stone (of Kimura)

Synonyms:

Castelnaudite, Hussakite, Phosphate of Yttria, Phosphyttrie, Tankelite, Tankite (of Haidinger)

Crystal Data

Crystallography:

Tetragonal - Ditetragonal Dipyramidal

Crystal Habit:

Short to long [001] prismatic crystals, with {010}, {110}, may be pyramidal {011}, equant, several other minor forms noted, to 5 cm. In radial or rosettelike aggregates of coarse crystals.

Twinning:

On {111}, rare

Physical Properties

Cleavage:

Good on {100}

Fracture:

Irregular/uneven to splintery

Tenacity:

Brittle

Moh's Hardness:

4.0 - 5.0

Density:

4.40 - 5.10 (g/cm³)

Luminescence:

May exhibit yellow cathodoluminescence.

Radioactivity:

Not Radioactive

Other:

Paramagnetic

Optical Properties

Color:

Yellowish brown, reddish brown, flesh-red, grayish white, wine-yellow, pale yellow, greenish; in transmitted light, colorless to very pale yellowish green, yellow, or yellowish brown

Transparency:

Translucent to opaque

Luster:

Vitreous to resinous

Refractive Index:

1.720 - 1.827  Uniaxial ( + )

Birefringence:

0.095 - 0.096

Dispersion:

n/a

Pleochroism:

Weak, dichroic; O = pink, yellow, or yellowish brown; E = brownish yellow, grayish brown, greenish

Occurances

Geological Setting:

An accessory mineral in alkalic to granitic rocks, well-developed in associated pegmatites; in gneiss and Alpine veins; a common detrital mineral in placers.

Common Associations:

Zircon, Monazite, Rutile, Anatase, Brookite, Hematite, Ilmenite, Gadolinite, Allanite, Apatite, Yttrotantalite, Thorite

Common Impurities:

May contain minor REE, Ca, U, Th, Si, F and other elements.

Type Locality:

Hidra (Hitterø), Flekkefjord, Vest-Agder, Norway

Year Discovered:

1824

View mineral photos:

Xenotime-(Y) Mineral Photos and Locations

Unusual Gem Categories

Magnetic Gems, Rare Earth Elements (REE) Gems

More Information

Mindat.org
Webmineral.com

Xenotime-(Y) is one of the very few yttrium gems. Xenotime is also a rare earth element (REE) mineral which means it contains some of the elements from the lanthanide series of elements. Although the chemstry of Xenotime is generally accepted as YPO4, analysis by electron microprobe reveals trace amounts of the REE elements dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lutetium (Lu), neodymium (Nd), samarium (Sm), terbium (Tb), thulium (Tm) and ytterbium (Yb). Along with these rare earth elements, the elements thorium (Th) and uranium (U) may replace the yttrium. Therefore, even though Xenotime is not generally considered to be a radioactive mineral, some Xenotime speciments may be weakly to strongly radioactive. Although there are two Xenotime minerals, Xenotime-(Y) with yttrium dominant, and Xenotime-(Yb) with ytterbium dominant, most Xenotime specimens (and gems) are Xenotime-(Y) with yttrium being dominant. Xenotime-(Yb) is very rare. Therefore, when referencing Xenotime, the -(Y) suffix is not often used.

Xenotime is unusual in that it is a paramagnetic mineral. Paramagnetism is a form of magnetism where certain minerals are attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, diamagnetic minerals, such as Barite and Ludlamite are repelled by magnetic fields and form induced magnetic fields in the direction opposite to that of the applied magnetic field.

Xenotime is named from the Greek words kenos (κευός) meaning vain and time (τιμή) meaning honor, more accurately translating to "vain glory". It was so named by French mineralogist François Sulpice Beudant as a rebuke of another scientist, Swedish chemist Jöns Jacob Berzelius, who claimed to have discovered a new chemical element in Xenotime which was later found to be the previously discovered yttrium. Xenotime was originally spelled "Kenotime" from the Greek word kenos, but over time "kenotime" was misread and misprinted as "xenotime".

Although Xenotime is found in many localities throughout the world, gem quality crystals are very rare. Xenotime gems are usually a translucent yellowish brown to reddish brown with vitreous to resinous luster and a Moh's hardness of 4-5.

Xenotime distribution: numerous localities but fine crystals are unusual. In Norway, from Lindesnes; on Hidra (Hitterö) Island; around Tvedestrand and Arendal; at Raade, near Moss; and elsewhere. From Ytterby, on Resarö Island, near Vaxholm, Sweden. In Switzerland, from the Binntal, Valais; in the Maderanertal, Uri; in the Tavetsch, Graubünden; and many other places. Large crystals from the Yazgulem Ridge, western Pamir Mountains, Tajikistan. At Sahamandrevo, near Ampangabe, Madagascar. In the Ishikawa district, Fukushima Prefecture, Japan. In Brazil, from Ataleia and Ibitiara, Minas Gerais; at Brumado and Novo Horizonte, Bahia. In the USA, in North Carolina, from placers in Polk, McDowell, and Burke Counties; on Cheyenne Mountain, El Paso County, and elsewhere in Colorado. In the Gunter quarry, near McKenzie Lake, Ontario, Canada.
 

  
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