“what is crystal cleavage and what does it state about the nature of matter?”
Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the microscope and to the naked eye.Cleavage plane can be described as the tendency of crystals to split along specific structural planes.
Cleavage plane is used mainly for the identification of the minerals. It is used in the electronic industry and also helps in cutting gems.