Stone cutting at the quarries of East Sioux Falls required skill and physical strength, especially because quartzite is very hard. Stone cutters valued the ability to judge where a boulder should be cut, and they used several important tools to make the work easier. The use of stone cutting tools has been traced back to the early Egyptians and Romans, and many of the tools used at East Sioux Falls are still used at local quarries today. A chisel, a metal tool with a cutting edge, is forced into stone with a hammer, which may be hand-held or pneumatic powered, and different chisels serve different purposes. A prying iron is inserted into cracks to separate large slabs of stone from bedrock. A hammer, with a metal head and wooden handle, is used with chisels to shape stone or sometimes struck with another hammer to break off chunks. Rasps and rifflers prepare the final surface finish, with a rasp sanding rough spots and a riffler enlarging holes. Plug and feather sets split large pieces of stone into smaller blocks by placing tapered metal plugs between two metal feathers in drilled holes, hammering them in sequence, and waiting for pressure to produce a crack along the cut line.