Some quarters have mint marks (the small letters indicating the minting location) that are misaligned or misplaced. These errors are often rare and sought after by collectors, making them valuable.
A double die obverse occurs when the design is stamped onto the coin more than once, creating a noticeable doubling effect. This error can make the quarter quite valuable, especially if the doubling is prominent.
If a quarter is struck on a planchet intended for another type of coin (such as a nickel or dime), it can become a valuable error coin. These mismatched planchets are unusual and highly collectible.
An off-center strike happens when the coin is not aligned correctly during minting, causing the design to be stamped off-center. This flaw is often prized by collectors for its distinctiveness.
A die crack occurs when a crack forms on the minting die, which then transfers to the coins. This flaw can create unique patterns on the quarter and is often sought after by enthusiasts.
A clipped planchet occurs when a coin is struck on a partially blanked or clipped piece of metal. This error results in a coin with an irregular edge, which can be quite rare and valuable.
Quarters that are in uncirculated condition and also exhibit errors such as scratches, smudges, or other minting imperfections are especially valuable. The combination of error and pristine condition can command higher prices in the market.