Knapping is the shaping of flint, chert, obsidian or other suitable material through the process of chipping off small pieces, thus shaping the piece into a desirable tool, weapon, or work of art. The process takes advantage of the fracture style of cryptocrystalline quartz and glass. Lacking cleavage or any natural weaknesses quartz fractures along smooth curved surfaces which often come to very sharp edges. This property is called conchoidal fracture.