The Collaborative International Dictionary of English v.0.48:

Petrification \Pet`ri*fi*ca"tion\, n. [Cf. F. p['e]trification.
   See Petrify.]
   1. See Petrifaction.
      [1913 Webster]

   2. Fig.: Obduracy; callousness. --Hallywell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

petrification
    n 1: the process of turning some plant material into stone by
         infiltration with water carrying mineral particles without
         changing the original shape [syn: petrifaction,
         petrification]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "petrification":
   ancient manuscript, antique, antiquity, archaism, arteriosclerosis,
   artifact, atherosclerosis, calcification, callusing,
   case hardening, cave painting, concretion, cornification,
   crystallization, eolith, firming, fossil, fossilization,
   granulation, hardening, hornification, induration, lapidification,
   lithification, mezzolith, microlith, neolith, ossification,
   paleolith, petrifaction, petrified forest, petrified wood,
   petroglyph, plateaulith, relic, reliquiae, remains, ruin, ruins,
   sclerosis, setting, solidification, steeling, stiffening, survival,
   tempering, toughening, vestige, vitrifaction, vitrification