Brockage Coin Errors: Mirror-Image Striking Mistakes

A brockage error occurs when a previously struck coin fails to eject from the press and remains stuck to one of the dies. When the next blank planchet is fed into position, it is struck by one normal die and by the stuck coin acting as an improvised die on the other side. The result is a coin with a normal design on one side and a mirror-image, incuse (sunken) impression of the design on the other.

What This Means

Brockages provide direct physical evidence of a production malfunction — a coin literally stuck in the press and striking subsequent coins. The stuck coin is called the "cap" or "die cap," and it progressively deteriorates as it strikes more blanks. Early brockage strikes show sharp, clear mirror images, while later strikes from the same cap show increasingly distorted and spread designs.

What to Look For

• One side with normal raised design, the other with a sunken mirror-image design
• The brockage side appears as an incuse (recessed) version of the opposite design
• Design elements on the brockage side are reversed left-to-right (mirror image)
• Look for slight spreading or distortion on the brockage impression
• The brockage side has no rim — the metal flows outward from the incuse impression
• Edge may show unusual characteristics depending on how the cap was seated

Common Mistakes to Avoid

• Confusing a damaged or hammered coin with a genuine brockage
• Not recognizing that the brockage image must be a mirror image of a real coin design
• Mistaking an indent (from a partial brockage) for a full brockage
• Not understanding that brockages can be obverse (showing the obverse in incuse) or reverse
• Assuming brockages are impossible on modern coins — they still occur occasionally

What Affects Value

Brockage error values depend on the clarity of the mirror image, the denomination, and the coin's overall condition. Clear, well-defined brockages on popular denominations are the most valuable. Full brockages are worth more than partial brockages. Older brockages tend to bring higher prices. Values range from $50 for modern, partial brockages to hundreds or more for early, clear examples.