Xenotime-(Yb)
Xenotime is a rare-earth phosphate mineral, the major component of which is yttrium orthophosphate (YPO4). The phosphate ions are described by a tetrahedral shape and coordinate to the center Y3+ metal ion in a way that closely resembles the structure of zircon (ZrSiO4). It forms a solid solution series with chernovite-(Y) (YAsO4) and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium.
Intro adapted from Wikipedia (CC BY-SA).
Xenotime-(Yb) is an IMA-recognized mineral species in the phosphate class, with the chemical formula Yb(PO₄).
It crystallizes in the tetragonal crystal system (space group I4_1/amd). It is a member of the Zircon structural group.
Key properties: specific gravity 5.85; White streak; Vitreous luster; optically uniaxial.
IMA symbol Xtm-Yb, IMA status: approved, named in 1998.
A primary phase in the saccharoidal albite unit of a gadolinite subtype of the NYF family of rare-element granitic pegmatite.
It is found associated with Ferrian muscovite, ferrocolumbite, albite, microcline, quartz.
Xenotime from the Greek for vain and honor, as the contained yttrium had been mistaken for a new element. The suffix, Yb, identifies the dominant rare earth element.