The Collaborative International Dictionary
Devitrify
Devitrify \De*vit"ri*fy\, v. t. To deprive of glasslike character; to take away vitreous luster and transparency from.
Wiktionary
devitrify
vb. (context of a glassy material English) To become crystalline and brittle
WordNet
devitrify
v. become crystalline
make (glassy materials) brittle or opaque
[also: devitrified]