Flintknapping requires the ability to control the way rocks break when they are struck. The best rock is somewhat brittle and uniform in texture and structure, lacking frost fractures, inclusions, or other flaws. This type of rock is very fine grained or non-grained. The best rocks for flint-knapping are chert, flint, chalcedony, quartzite, jasper, and obsidian. Chert and flint are silica-rich rocks found throughout the Midwest in limestone and dolomite deposits. These rock types, when struck with another rock, piece of antler, or bone, will fracture or break in a characteristic pattern called a conchoidal fracture. This creates a rock fragment called a flake.