Cleavage In the crystal structure of many minerals, some atomic bondsare weaker than others. It is along these weak bonds that minerals tend to break when they are stressed. Cleavage(Kleiben= carve) is the tendency of a mineral to break(cleave) along planes of weak bonding. Not all minerals have cleavage, but those that do can be identified by the relatively smooth, flat surfaces that are produced when the mineral is broken.