Mineral cleavage refers to the tendency of a mineral to break along specific planes of weakness in its crystal structure. This property is determined by the arrangement of atoms within the mineral, which can create flat surfaces when the mineral is fractured. Cleavage is an important characteristic used to identify minerals, as different minerals exhibit distinct cleavage patterns. The quality of cleavage can vary, with some minerals displaying perfect cleavage, while others may show only good or poor cleavage. Common examples of minerals with notable cleavage include mica, which splits into thin sheets, and calcite, which cleaves in three directions at right angles.