In
lithic analysis (a subdivision of
archaeology), an
eraillure is a small secondary flake removed from a
lithic flake's bulb of force, which is a lump left on the dorsal surface of a flake after it is detached from a core of
tool stone during the process of
lithic reduction. The mechanics of eraillure formation are related to the propagation of a
Hertzian cone[?] of force through the
cryptocrystalline matrix of the stone, but the particulars are poorly understood. Eraillures form only when a
hammerstone is used for lithic reduction, and then only occasionally; use of
soft hammer[?] fabricators made from
bone,
antler, and
wood produce different flake characteristics.