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Noun: thulium  thoo-lee-um
  1. A soft silvery metallic element of the rare earth group; isotope 170 emits X-rays and is used in small portable X-ray machines; it occurs in monazite and apatite and xenotime
    - Tm, atomic number 69

Derived forms: thuliums

Type of: metal, metallic element

Part of: apatite, monazite, xenotime

Encyclopedia: Thulium