prospector

from WordNet (r) 3.0 (2006)

prospector
    n 1: someone who explores an area for mineral deposits

from The Collaborative International Dictionary of English v.0.48

Prospector \Pros"pect*or\, n. [L., one who looks out.]
   One who prospects; especially, one who explores a region for
   minerals and precious metals.
   [1913 Webster]