Devitrification /(?)/

De·vit·ri·fi·ca·tion

Devitrification

n.
  1. The act or process of devitrifying, or the state of being devitrified. Specifically, the conversion of molten glassy matter into a stony mass by slow cooling, the result being the formation of crystallites, microbites, etc., in the glassy base, which are then called devitrification products.