Source : Webster's Revised Unabridged Dictionary (1913)

Opalize \O"pal*ize\, v. t. [imp. & p. p. {Opalized}; p. pr. &
   vb. n. {Opalizing}.] [Cf. F. opaliser.]
   To convert into opal, or a substance like opal. --Lyell.

Source : WordNet®

opalize
     v 1: make opalescent [syn: {opalise}]
     2: replace or convert into opal; "opalized tree trunks" [syn: {opalise}]