The Collaborative International Dictionary of English v.0.48:

Pollucite \Pol"lu*cite\, n. [See Pollux, and 4th Castor.]
   (Min.)
   A colorless transparent mineral, resembling quartz, occurring
   with castor or castorite on the island of Elba. It is a
   silicate of alumina and c[ae]sia. Called also pollux.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pollux \Pol"lux\, n. [L., the twin brother of castor; also, the
   constellation.]
   1. (Astron.) A fixed star of the second magnitude, in the
      constellation Gemini. Cf. 3d Castor.
      [1913 Webster]

   2. (Min.) Same as Pollucite.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Pollux
    n 1: the brightest star in Gemini; close to Castor