On the Presence of Faces in the Habit of Growing Crystals

Presence and size of a face in the habit are conditioned by the value of relative growth velocity R_A/R_{crit A} with respect to the critical growth velocity. It has been established that during the growth of crystals only certain values of relative growth velocities R_A/R_{crit A} occur. Faces of KBC crystals realize values of R_A/R_{crit A} between 0 and 2. Unity is the demarcation level below which appearance and above which disappearance of faces takes place. Edges and corners of crystals are places where new faces appear during changes in growth conditions.