rs a Z

is denominated glass forming ability (GFA). A maximum allowed fraction of crystals, Xc, usually taken between mate GFA would then avoid exhaustive laboratory investi-gations, and this is thus a key step for efficient development of new glasses and glass-ceramics. On the other hand, once a glass is made, for instance by fast quenching a melt, its stability against crystallization can be easily investigated. The resistance of a given glas