What is cleavage in minerals?

• A. Cleavage is the tendency of a mineral to break along a smooth plane.
• B. Fracture is the tendency to break into uneven, random-sized pieces.
• C. Crystal form is the natural shape a mineral acquires during its formation.
• D. Lava is molten rock above ground.

Answer: (A)

Cleavage in minerals is the tendency to break along smooth, flat planes where the crystal structure has weaker bonds. This means the mineral splits cleanly along those directions, producing flat surfaces because the bonds are easier to break in those specific orientations. Some minerals show perfect cleavage and fracture into very smooth faces, while others have only indistinct or poor cleavage.

This concept differs from fracture, which is breaking into uneven, irregular pieces without preferred planes. It also isn’t about crystal form, which is the overall natural shape set by the mineral’s internal lattice during growth, nor about lava, which is molten rock erupted onto the surface. The statement that describes breaking along smooth planes best captures cleavage.