Brockage

Brockage

A brockage is a striking error in which a previously struck coin fails to eject from the die and acts as a die itself against the next planchet fed into the press. The result is a coin with one normal face and one face bearing a mirrored, incuse (sunken) version of the stuck coin's design. Brockages are among the most visually dramatic and readily identified mint errors.

Explanation

In a high-speed coinage press, the dies strike each planchet and the finished coin is ejected. Occasionally a struck coin adheres to one die, usually the obverse. When the next planchet is fed in, it is struck simultaneously by the normal opposite die and by the face of the retained coin. The new coin therefore receives a correct impression from one die and a negative, mirror-image transfer of the retained coin from the other. If the stuck coin remains in place for many strikes it can deform into a "cap", producing capped die strikes and progressively shallower brockages.

Identification

The key diagnostic is the mirror relationship between the two faces: the error side shows the same design that appears on the coin's normal side, but incuse and reversed left-to-right. A full brockage shows the complete design; an offset or partial brockage shows only part of it, depending on how the planchet was positioned. The error face is often weakly detailed or enlarged, because the retained coin is slightly larger than the die face it substitutes for.

Example

On an Australian decimal coin, a typical brockage shows the standard obverse portrait on one side and a blurred, incuse mirror of the Queen's (or King's) portrait on the other. Related errors include the brockage of a brockage, where the error coin itself becomes stuck, and uniface strikes, where one die fails to strike at all.

Important Considerations

• Type: Full brockages command the strongest premiums; partial and off-centre brockages are more affordable entry points.
• Authentication: A genuine brockage is integral to the strike. Any incuse design that appears scratched, pressed, or added after striking (for example by an engine-turned lathe) should be treated as tampering.
• Condition: Because the press was malfunctioning, brockages often show weakness, doubling or metal flow consistent with an abnormal strike - their presence supports authenticity.

In summary, a brockage is the mirrored impression of one coin transferred onto another by a stuck coin in the press, and its unmistakable incuse mirror image makes it one of the most collectible and easily verified of all mint errors.