The Collaborative International Dictionary of English v.0.48:

Scagliola \Scagl*io"la\, n. [It. scagliuola, dim. of scaglia.
   See Scaglia.]
   An imitation of any veined and ornamental stone, as marble,
   formed by a substratum of finely ground gypsum mixed with
   glue, the surface of which, while soft, is variegated with
   splinters of marble, spar, granite, etc., and subsequently
   colored and polished.
   [1913 Webster]