Abstract: Vitroceramic products having a dispersed devitrified phase in a vitreous body, of fine grain, are made from particular compositions having specific limitations as to the content of particular ingredients, by methods which involve a controlled nucleation, a period of rest at an intermediate temperature, a controlled increase in temperature to achieve advanced crystallization, and a period of rest before cooling freely. All operations are carried out below the softening point of the glass and preferably between the point of thermal dilation and below softening temperature. The qualities of the products can be varied by changes in qualitative and quantitative composition.