Bonds between atoms are not all equally strong. Atoms may be held in some positions by powerful bonds, and in other positions by weak bonds. This variation in bonding explains why some crystals can be cleaved. Cleavage can take place when the weak bonds lie along a flat surface called a cleavage plane. When the crystal is cut along this plane, the weak bonds break and the crystal splits, exposing the flat surface.

Graphite, left, consists of layers of carbon atoms. Weak bonds hold the layers together and form cleavage planes, right. The crystal splits into tablets along these planes.

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This page was last updated on 02/22/2010.