Fig. 1: Illustration of different types of crystals.

The exfoliable layered crystal, non-exfoliable layered crystal, non-exfoliable non-layered crystal, and exfoliable non-layered crystal are illustrated.
The exfoliable layered crystal, non-exfoliable layered crystal, non-exfoliable non-layered crystal, and exfoliable non-layered crystal are illustrated.