Xenotime - YPO4

Xenotime is a rare earth phosphate mineral (YPO4). Due to uranium and thorium impurities, some xenotime specimens may be weakly to strongly radioactive.

The etymology of the name xenotime is from the Greek words vain and honor because the yttrium contained within it was first thought to be a new element. Xenotime was first described for an occurrence in Vest-Agder, Norway in 1832.

The structure of xenotime is analogous to Zircon ZrSiO4, with PO4- tetrahedral units replacing SiO4-. Other rare earth elements, especially erbium may partially replace Y. Zr, Th, U or Ca may also replace some Y; the PO4- tetrahedral units can be replaced by SO24- ore by SiO4--

Xenotime is a very rare mineral, it is an accessory mineral in some alkaline granite, syenite and similar siliceous rocks.

Optical properties:
Color: Colorless or pale yellow-brown
Form: Euhedral stubby bipyramidal crystals
Relief: Moderate
Interference colors: Very strong


Bibliography



• Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Optical Mineralogy : The Nonopaque Minerals by Phillips / Griffen
• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc




Photo
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Xenotime crystal with Arfvedsonite inclusions (blue). PPL image. 10x (Field of view = 2mm)
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Xenotime crystals. PPL image. 10x (Field of view = 2mm)
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Xenotime crystals. XPL image. 10x (Field of view = 2mm)
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Xenotime and Aegirine crystals. PPL image. 10x (Field of view = 2mm)
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Xenotime and Aegirine crystals. XPL image. 10x (Field of view = 2mm)
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Xenotime crystals. PPL image. 2x (Field of view = 7mm)
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Xenotime and Aegirine crystals. PPL image. 2x (Field of view = 7mm)
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Xenotime and Aegirine crystals. XPL image. 2x (Field of view = 7mm)
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Xenotime crystals. PPL image. 2x (Field of view = 7mm)