Cleavage can tell you more about crystal structure which aids in mineral identification, while fracture defines the irregular chipping shape of a mineral.
Cleavage is how a mineral crystal breaks along specific internal planes. Cleavage quality can vary, and we use terms like perfect, imperfect, distinct, good, fair, and poor to describe it. Some minerals exhibit no cleavage, while others have multiple cleavages with different qualities. When a mineral is struck, it produces smooth surfaces oriented in a particular way relative to the crystal’s atomic arrangement. These planes demonstrate areas of weak bonding within the crystal structure. Minerals with cleavage will break into fragments with distinctive shapes. Geometric terms like cubic, octahedral, rhombohedral, or prismatic describe the cleavage.
Fracture differs from cleavage. It occurs when a mineral breaks in a more random pattern, resulting in rough-edged, chipped shapes. Minerals that exhibit cleavage can also exhibit fracture. If a mineral with cleavage is chipped in a certain way, it will fracture rather than cleave.
