devitrify
verb
de·vit·ri·fy (ˌ)dē-ˈvi-trə-ˌfī 
devitrified; devitrifying; devitrifies
transitive verb
: to deprive of glassy luster and transparency
especially : to change (something, such as a glass, glassy rock, or enamel) from a vitreous to a crystalline condition
devitrification
(ˌ)dē-ˌvi-trə-fə-ˈkā-shən
noun 
Word History
Etymology
French dévitrifier, from dé- de- + vitrifier to vitrify
First Known Use
1832, in the meaning defined above