“Hard hammer percussion - that is, striking the tool with another stone to remove flakes." Whittaker 1994., 27
The following are indications of the use of a hard hammer or percussor:
-unlipped and often large butt and pronounced bulb of percussion.
-a clear cone and marked point of percussion.
-pronounced conchoidal fracture marks on the bulb.
-clear concentric percussion rings and fissures.
see Ohnuma & Bergman 1983.
see movie basic flint knapping with hard hammer