The Collaborative International Dictionary of English v.0.48:

Marbleize \Mar"ble*ize\, v. t. [imp. & p. p. Marbleized; p.
   pr. & vb. n. Marbleizing.]
   To stain or grain in imitation of marble; to cover with a
   surface resembling marble; as, to marbleize slate, wood, or
   iron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

marbleize
    v 1: make something look like marble; "marbleize the fireplace"
         [syn: marbleize, marbleise]