Mint Error Types
Errors created during planchet preparation, striking, collaring, ejection, or another production event.
Blank Planchet Type 1
An unstruck blank punched from coinage strip before the upsetting mill forms a raised rim.
Blank Planchet Type 2
An unstruck planchet that has passed through the upsetting mill and shows a prepared rim.
Clipped Planchet
A blanking error in which part of the coin blank is missing because punches overlapped the edge or a prior hole.
Wrong Planchet Error
A coin struck on a planchet intended for another denomination or another coinage specification.
Wrong Metal or Off-Metal Strike
A design struck on metal or stock not intended for that issue.
Split Planchet Before Strike
A defective planchet separates before striking, leaving a thin coin with weak or incomplete design.
Split Planchet After Strike
A flawed planchet separates after receiving the design, sometimes leaving matching halves.
Lamination Error
Metal separates, peels, cracks, or flakes because of impurities or poor bonding in the planchet strip.
Alloy Mix and Woodgrain Errors
Improperly blended alloy can create streaked coloration or structural differences in a genuine planchet.
Rolled-Thin Planchet
Coinage strip rolled below specification can produce a normal-diameter but underweight, weakly struck coin.
Rolled-Thick Planchet
Strip above specification can create an overweight planchet with unusual strike characteristics.
Tapered Planchet
Uneven strip thickness produces a coin that is measurably thicker on one side and thinner on the other.
Off-Center Strike
The planchet is not fully positioned between the dies, leaving part of the design missing and an unstruck crescent.
Broadstrike
The coin is struck without proper collar restraint and spreads beyond its normal diameter.
Partial Collar Strike
Only part of the planchet is contained by the collar, often creating a stepped railroad-rim effect.
Double Strike
A coin receives a second strike after failing to eject normally.
Multiple Strike
A coin is struck three or more times, sometimes with dramatic movement between impressions.
Flipover Double Strike
The coin flips between strikes, producing a second impression from the opposite orientation.
Foldover Strike
A planchet folds before or during striking and receives design across doubled metal.
Brockage Error
A struck coin sticks to a die and impresses an incuse mirror image onto the next planchet.
Die Cap Error
A struck coin remains attached to a die and stretches into a cap through repeated strikes.
Capped Die Strike
A die capped by a stuck coin produces distorted, softened, or brockage-like strikes on later planchets.
Struck Through Grease
Grease or compacted debris fills die recesses and prevents parts of the design from striking fully.
Struck Through Debris
Foreign material between die and planchet leaves an incuse void or texture during striking.
Retained Struck-Through
The foreign material that caused a struck-through remains embedded in the coin.
Indented Strike
A second planchet overlaps the struck planchet, leaving a smooth unstruck indentation.
Bonded Pair
Two planchets become physically joined during striking, sometimes producing matching distortions.
Mated Pair
Two error coins produced in the same press event fit together and explain each other’s shapes.
Misaligned Die Strike
One die is laterally displaced while the other face remains normally centered.
Rotated Dies
The obverse and reverse dies are out of their normal rotational alignment.
Mule Error
Obverse and reverse dies intended for different coin types are paired in one strike.
Edge Lettering Error
Lettering applied to the edge is missing, doubled, overlapped, inverted, or otherwise abnormal.
Missing Clad Layer
One outer clad layer is absent before striking, exposing the core and changing weight and color.
Double Denomination Strike
A previously struck coin is struck again by dies of another denomination.