Zonary growing of crystals bounded by plane crystal faces, which occur by slight variation in the composition of a crystal due to separation or interruptions of the crystal phases during growth.
See Alexandrite Tsarstone collectors guide, Definition of Zonary growth, http://w.alexandrite.com/viewpage.html?id=GG-085-00001 (Zonary growing of crystals bounded by plane crystal faces, which occur by slight variation in the composition of a crystal due to separation or interruptions of the crystal phases during growth.) (as of Jun. 01, 2026, 04:45 GMT).