Crystal cleavage refers to the way a crystal breaks along specific planes of weakness in its structure. This property is determined by the arrangement of atoms within the crystal lattice, which influences how the crystal will fracture when subjected to stress. Different minerals exhibit varying types of cleavage, such as micas that split into thin sheets or halite that breaks into cubes. Understanding crystal cleavage is important in fields like mineralogy and geology, as it helps identify minerals and assess their properties for practical applications.