xenotime

from WordNet (r) 3.0 (2006)

xenotime
    n 1: a brown-to-yellow mineral that is a phosphate of yttrium in
         crystalline form

from The Collaborative International Dictionary of English v.0.48

Xenotime \Xen"o*time\, n. [Gr. xeno`timos honoring guests or
   strangers; xe`nos guest, stranger + timh` honor: cf. G.
   xenotim.] (Min.)
   A native phosphate of yttrium occurring in yellowish-brown
   tetragonal crystals.
   [1913 Webster]