Part V. Planchet Errors:

Alloy Errors:

Rolling-Induced Fissures

Definition: A fissure that opens up in the coin metal strip during rolling.

Rolling-induced fissures occur when abnormally brittle metal splits under internal tensile stresses generated during rolling-out of the coin metal strip.  Facing edges of the fissure are usually beveled.  Rolling-induced fissures share the same etiology as ragged perforations (“blowholes”).  Blowholes show a similar beveled perimeter.  The only difference is that blowholes are defined by a wider aperture.

This 1978 cent shows two rolling-induced fissures, the only known case in which more than one fissure is present in a coin.  The fact that the two fissures invade the coin from opposite directions demonstrates that this is not an “end-of-strip” phenomenon.