#pollucite  a rare mineral that is an important source of cesium
  supertype:  mineral  solid homogeneous inorganic substances occurring in nature having a definite chemical composition
  substance:  rubidium
  subtype:  cesium__caesium__Cs__atomic_number_55  a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal
     subtype:  cesium_137  a radioactive isotope of cesium used in radiation therapy

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