Part VI: Striking Errors:

Struck Through Errors:

Retained Strike-through:

Plastic

A retained, struck-through error (otherwise known as a “struck-in” error or an “embedded struck-through”) will usually be demarcated from the rest of the coin by a narrow fissure.  If it is a sizable piece of debris, it will push the coin’s weight beyond normal tolerances.

Almost everything imaginable has been found struck into coins.  The most common subjects are pieces of scrap coin metal.

Different kinds of material can be found retained after a coin is struck.

2006 Mexican $100 comprised of an aluminum bronze ring with a 0.925 sterling silver core. It has been both struck through and has retained a thick plastic tape on either face of the coin.