Mineralpedia Details for Xenotime-(Y)

The yttrium in Xenotime had been mistaken for a new element at the time of its discovery, hence it being named for the Greek for “vain” and “honor.” While exceptional crystals are uncommon, there are abundant localities at which Xenotime can be found occurring as an accessory mineral in rocks with alkali to granitic compositions and pegmatites associated with these rocks. It can also be found in Alpine veins, gneiss, and commonly in placer deposits. Xenotime is paramagnetic, meaning it is only magnetically attracted when there is an external magnetic field applied. Xenotime can exhibit a yellow cathodoluminescence. May be susceptible to or resistant to acids, depending on the composition.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/xenotime-(Y).pdf

Formula

YPO₄ 

Crystal System

Tetragonal 

Crystal Habit

Radial, Prismatic, Massive - Granular 

Cleavage

Perfect, None, None 

Luster

Vitreous - Greasy 

Color

yellowish brown, greenish brown, gray, reddish brown, brown 

Streak

white 

Class

Tetragonal - Ditetragonal Dipyramidal 

Fracture

Splintery 

Hardness

4-5 

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Dark yellow micro crystals of Xanthoconite to about 0.75mm.

Superb terminated Xenotime with multiple modifications. Seems to be a little color changing under various lights. Overall 2x1x1cm.

Translucent brownish red tetragonal prism with first and second order pyrimidal terminations. There are two crystals in parallel.

Large dark red plates of Xenotime to 5cm in biotite. I am assuming this is (Y).

An aggregate of several Xenotime crystals to 3cm. An excellent specimen by any measure.

Pink long bladed crystals to 1.5cm.