The process of making stone tools by removing flakes from a larger mass, by percussion or pressure from another tool. Percussion flaking is done by striking the stone to be chipped with another stone or bone. Pressure flaking is done by pressing a blunt-pointed tool of antler or bone against the edge to be worked. Flaking is feasible with materials that are glassy in nature and fracture evenly (as obsidian, flint); it is not feasible with materials such as granite or sandstone which in general are ground.