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pollucite

noun
  1. a colourless rare mineral consisting of a hydrated caesium aluminium silicate, often containing some rubidium. It occurs in coarse granite, esp in Manitoba, and is an important source of caesium. Formula: CsAlSi 2 O 6 . 1/2 H 2 O

Word Origin for pollucite

C19: from Latin polluc-, stem of Pollux + -ite 1; originally called pollux, alluding to Castor and Pollux, since it was associated with another mineral called castor or castorite
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012