Struck trough fragment

This type of error occurs when a metal fragment gets trapped in the beating chamber along with the newly inserted planchet and then hit by dies at the same time. The fragment then detaches itself from the newly minted coin leaving a cavity with variable width and depth according to its size (E.B.26, E.B.27 and E.B.28). When the planchet is beaten through a fairly thin fragment, the ridges of the coin will be partially seen inside the cavity. This mistake is often incorrectly referred to as metal deficiency. In fact, we can distinguish the two errors by examining the weight. It is a coin struck through a metal fragment when its weight is correct. Otherwise it is a lamination error.