Vitrification is the process of converting a material into glass or a glass-like substance, typically through the application of high heat. In geology, vitrification is significant in the study of volcanic rocks, particularly obsidian, and in understanding the effects of extreme heat on geological materials.
Reference: Dingwell, D. B. (1996). “Volcanic Glasses.” Reviews in Mineralogy and Geochemistry, 32(1), 69-106.