Bidding on a 10c Roosevelt dime struck on a nail stands at $7,637 at Heritage Auctions.

The lot is offered as part of the FUN US Coins Signature Auction in Tampa, Florida on January 6-11.

It's unknown how the nail came to be stamped with the Roosevelt dime

It's one of the most intriguing errors ever produced at the US Mint and will likely prove a major draw to collectors. The date is unknown. They have been minted since 1946.

Heritage comments: "This spectacular error is one of the most unusual pieces to ever come out of a United States Mint.

"This zinc-coated sixpenny nail found its way into the coinage production line during the minting of Roosevelt dimes, and apparently escaped through normal distribution channels.

"We have no doubt that this striking error will be the prize of its new owner when it falls to the auctioneer's hammer."

While it's probable that an employee of the mint created the error deliberately, Tom DeLorey of Coin World suggested at alternate explanation.

He explains that when his former mentor was working at the mint, he noticed a nail by the press: "He asked the press operator what it was for, and the press operator said that when the feed tube clogged he used the nail to clear the feed tube, which had a slot down the side for this very purpose!

"So, although a cent strike on a nail is very unlikely, there does exist the chance that at least one such strike was a legitimate random error."

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