The Collaborative International Dictionary of English v.0.48:

Spall \Spall\, n. [Prov. E. spall, spell. See Spale, Spell a
   splinter.]
   A chip or fragment, especially a chip of stone as struck off
   the block by the hammer, having at least one feather-edge.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spall \Spall\, n. [OF. espaule; cf. It. spalla. See Epaule.]
   The shoulder. [Obs.] --Spenser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spall \Spall\, v. t.
   1. (Mining) To break into small pieces, as ore, for the
      purpose of separating from rock. --Pryce.
      [1913 Webster]

   2. (Masonry) To reduce, as irregular blocks of stone, to an
      approximately level surface by hammering.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spall \Spall\, v. i.
   To give off spalls, or wedge-shaped chips; -- said of stone,
   as when badly set, with the weight thrown too much on the
   outer surface.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spall
    n 1: a fragment broken off from the edge or face of stone or ore
         and having at least one thin edge; "a truck bearing a mound
         of blue spalls" [syn: spall, spawl]