#thorium__Th__atomic_number_90  a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands
  supertype:  metallic_element__metal  any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.
  substance of:  monazite  thorite
  subtype:  thorium-228__thorium228__radiothorium  radioactive isotope of thorium with mass number 228

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