The phosphorus slag produced as the waste of yellow phosphorus manufacturing was studied for the production of calcium-aluminum-silicone system glass ceramic materials. The thermal behavior and crystallization processes of fine powders of parent glass with chemical composition (wt. %) 52-60 SiO2, 22-28 CaO, 2-10 Al2O3, 3-8Na2O+K2O, 1.7-2.1P2O5 and 1.6-2.0 F were carefully studied by DTA, XRD and SEM techniques. The desired sequence of events, i.e. nucleation, sintering and devitrification occurred by heat treating the glass powder. The results showed that the phosphorus slag can be as a main raw material directly in production of the glass ceramic.