Source : Webster's Revised Unabridged Dictionary (1913)

Clastic \Clas"tic\, a. [Gr. ? br?, fr. ? to break.]
   1. Pertaining to what may be taken apart; as, clastic anatomy
      (of models).

   2. (Min.) Fragmental; made up of brok? fragments; as,
      sandstone is a clastic rock.

Source : WordNet®

clastic
     adj 1: of or belonging to or being a rock composed of fragments of
            older rocks (e.g., conglomerates or sandstone)
     2: capable of being taken apart; "the professor had a clastic
        model of the human brain"