Different types of common coin errors to use as a reference. New people look here to determine your error. Blank or Planchet This is simply a planchet intended for coinage but not struck with a die. In the process of minting, planchets are first struck from strips of thin metal. A planchet on which the rims have not been milled upward is more valuable than a processed planchet. Note: The rim on a blank is not raised, while the rim on a planchet is raised. Defective Die A coin shows a raised line on its surface. This is caused by a crack in the die used to strike the planchet. Coins sometimes show an unstruck area resulting from a break in the die. This is known as a cud mark. In U.S. coinage, many coins from the Morgan Dollar series series show slight die cracks. Lamination A coinage defect consisting of a portion of the metal separating from the rest due to impurities or internal stresses. Lamination flaws occur primarily when a foreign material or gas oxide becomes trapped within the planchet (the metal blank used as a coin). This error is especially common to the modern US Cent having a zinc metal base plated with a thin sheeting of copper. Off Center This error occurs when the coin has been struck outside of the planchet, due to the planchet improperly entering the coinage press. Broadstrike Broadstrike errors are produced when the collar die malfunctions. The collar is the circular die surrounding the anvil (lower) die. It applies the edge device (reeded edge, plain edge) and prevents the metal of the coin being struck from flowing outside of the confines of the die. When the collar is prevented from working properly during striking, it may rest below the surface of the anvil die. All denominations of U.S. coins with a broadstrike have a plain edge. Clipped planchet Occasionally a misfeed can occur where a strip isn't fed through far enough. When this happens, the punches strike an area of the strip which overlaps the hole left by the previous strike. The result is a blank with a piece missing. A clipped planchet is straight, curved, ragged, incomplete, or elliptical. Wrong planchet This occurs when a denomination is struck on a planchet of a different denomination. Some examples include cents struck on dime planchets, nickels on cent planchets, or quarters on dime planchets. Sacagawea dollars have been reported with statehood quarter designs on the reverse. A much rarer error is a U.S denomination struck on a foreign planchet (17th,18th, and 19th centuries only). Brockage A mirror image of a coin has been struck on both sides of the planchet. This error typically occurs when a coin remains on either die after striking. The second coin receives the image from the die, though its blank other side also receives the image of the struck coin. The result is an incuse mirror image, and the coin is known as a brockage error. Multiple Strike This occurs when the coin has an additional image on one side from being struck again, off center. The result is sometimes mistaken as being a "doubled die". Note: Also referred to as 'double exposure.' Overdate In the past, it was a common practice for a mint to use a certain die until it broke. As some dies would last for multiple years, a figure would be punched over the old date. For example, some 1942 Mercury dimes show a 1 beneath the 2. Sources: http://en.wikipedia.org/
Thank you. I am very happy that you took the time to post this. I was aware of it, but I am sure that many newer users are not.
Some of those are wrong or at least not quite right and need improvement. A blank and a planchet are not the same thing. the piece punched from the strip is a blank, after it receives the upset rim it is a planchet. Your last sentence makes that clear but the second sentence has planchets being punched from the strip. Less confusion if termenology is kept consistant. Bubbles in the plating on a post 1981 cent are not an example of an lamination The Sacagawea dollar with the state quarter design on one side is NOT a wrong planchet error, it is a mule. A Sac dollar struck on a coppernickel clad quarter planchet WOULD be a wrong planchet error. US coins struck on a foreign planchet come on 20th century coins as well, but I don't think they come on 17th century. Not too many US coins from the 1600's. Brockage A mirror image of a coin has struck on BOTH sides of a coin?? A multiple strike can have image on BOTH sides of the coin from the second or later strike. In fact there are MANY ways to have multiple struck coins. Double struck in collar, double struck in collar with rotation between strikes, flip over double strike (Coin flips over between strikes but falls back into the collar), second strike off center, second strike offcenter with another planchet between one of the dies and the coin, second strike off center with another coin between one of the dies and the coin (In that case the off-center strike will show and partial image on one side and a partial brockage on the other. There are other possibilities. Overdates: There are only two cases in US coinage where a die was used and then had another cut over the old date and both are 1806/5 coins (half dime? and half dollar). All other overdates before 1909 were the result of a new date being punched into an unused die that had not been hardened for use yet. All overdates after 1908 are actually doubled dies. Late in the year the mint starts making a supply of dies for the coming year and for awhile they are making dies for both years at the same time. Until recently it took mulptiple sweezes of the hubbing press, with the die being annealed between hubbings, to bring up the design fully. If the die was hubbed with one date and then accidently brought back to the wrong hubbing press that was making dies with the other date the result was a doubled die that showed one date over the other.
I wouldn't consider overdate as an error. Error is something that's not supposed to be intended. Overdates are usually done as there were either not enough dies in the first place or just purely economical costs.
