“…Veytizou et al (28) reported that the presence of both ZrO 2 and amorphous silica, in addition to the presence of interstitial silicon, can cause the precipitation of ZrSiO 4 : the interstitial silicon can indeed diffuse and dissolve into crystalline ZrO 2 until the solubility limit is reached. The formation of this phase, called zircon (23), has been reported by several authors (13,23,(25)(26)(27)(29)(30)(31)(32).…”