Source : Webster's Revised Unabridged Dictionary (1913)

Gummite \Gum"mite\, n. [So called because it occurs in rounded
   or flattened pieces which look like gum.] (Min.)
   A yellow amorphous mineral, essentially a hydrated oxide of
   uranium derived from the alteration of uraninite.

Source : WordNet®

gummite
     n : a gummy orange mixture of uranium oxides and silicates
         occurring naturally in the hydration and oxidation of
         pitchblende