Crystalogy is the art of the Tracers, who train exhaustively to learn complex arrays. An array is a design, usually circular, made either from loose crystal dust or from crystal dust suspended in ink, paint, or chalk, that executes a spell at the command of its tracer. Crystology is an integral part of Crystallurgy, as it allows its user to transform matter into whatever shape or form they desire.
It is important to note that Crystalogy must abide by the law of equivalent exchange. It cannot create, and it cannot destroy, not directly. It can only transform matter from one form to another. The energy required to perform this transformation is supplied by the crystal array, which is consumed in the process of casting.