When a hammerstone and a core fall in love . . .Flint Knapping is the process of using a hammerstone (a small rock/cobble) and hitting it against a type of rock (i.e. a core), like obsidian or chert, that breaks into nice small pieces (i.e. flakes) that can be further worked into tools like scrapers, spear points, projectile points, knives, etc.