The Collaborative International Dictionary of English v.0.48:

Fossick \Fos"sick\, v. i. [Dial. E. fossick, fossuck, a
   troublesome person, fussick to potter over one's work,
   fussock to bustle about; of uncertain origin. Cf. Fuss.]
   1. (Mining) To search for gold by picking at stone or earth
      or among roots in isolated spots, picking over abandoned
      workings, etc.; hence, to steal gold or auriferous matter
      from another's claim. [Australia]
      [Webster 1913 Suppl.]

   2. To search about; to rummage.

            A man who has fossicked in nature's byways. --D.
                                                  Macdonald.
      [Webster 1913 Suppl.]