This unique striking is a proof mule, struck by the San Francisco Mint on a proof Ike Dollar planchet. The obverse shows Jefferson's portrait and the 1976-S date and Mint Mark.

The reverse shows the design of the dime struck by either a proof Dime obverse die or hub. This is the only known U.S. coin struck in proof, with two different designs from two different denominations, on a large proof planchet.

This proof Nickel/Dime mule is possibly a die trial or test piece. The Jefferson Nickel obverse die was perfectly centered when it was struck into the Ike Dollar blank. A reverse Dime die or hub was deliberately used to strike the dime design on the reverse.

It is unique in several ways. Not only is it the only known proof U.S. mule, it is also the only known U.S. mule struck on a larger planchet. This unique striking provides insight into the U.S. Mint's testing and production methods.

The San Francisco Mint struck Jefferson Nickels in 1976 but only in proof. In addition, the San Francisco Mint only struck proof Eisenhower Dollars in copper-nickel clad intended for the Bicentennial Ike coinage of 1976. Therefore, this is obviously a proof mint error or die trial from the San Francisco Mint.

It is incredible that this dramatic proof mule was discovered and subsequently sent to NGC for authentication. Although this mint error or die trial was struck 40 years ago in the San Francisco Mint, it was previously unknown to the numismatic community until it's recent discovery. Having dealt in major mint errors, die trials and unique numismatic rarities for 40 years, I consider this piece to be one of the most spectacular and unique U.S. coins of all time.

Dave Camire and NGC authenticated and certified this unique striking as a U.S. 1976-S Jefferson Nickel struck into an Ike Dollar blank. This unique proof striking was part of a 40 year old proof and mint state collection of mint error coins and die trials which recently surfaced and was certified by NGC. After Fred Weinberg, Andy Lustig, Mike Diamond, Jon Sullivan and other experts studied this coin, the consensus was that this Nickel/Dime Mule is the only known proof U.S. mule.

Fred Weinberg stated that "I've handled mint state mules and coins struck by two obverse or two reverse dies, but this incredible proof Nickel/Dime striking is unique. It is amazing that it survived and was just discovered after 40 years." Fred Weinberg is the PCGS consultant for authenticating mint errors and is a recognized world expert on the minting process.

Andy Lustig, co-publisher of U.S. Patterns and the editor of Mint Error News, when shown this unique mule, stated that it is "not just unique, but practically unimaginable! I've never seen or heard of anything similar from any U.S. Mint."

Mike Diamond described this on his Error Coin Information Exchange as "a large dollar or dollar sized planchet that was weakly struck by a proof Nickel obverse die on one face and a proof Dime obverse die on the other face. The Dime design was hubbed or transferred into a larger area marked by many irregular features." Mike Diamond, error coin specialist, is lead author of Coin World's weekly "Collectors' Clearinghouse," which delves into how errors and varieties are created in U.S. coinage.

Jon Sullivan examined this unique striking and said that "this is the only known muling of a U.S. Dime obverse and a U.S. Nickel obverse. This is one of the most fascinating mint errors I have ever seen." Jon Sullivan of sullivannumismatics.com is a recognized mint error expert and full time mint error dealer.

There are 14 known Sacagawea Dollar/State Quarter mules. Several of these have sold as high as $125,000. There are 3 known Cent/Dime mules. These have traded for as high as $138,000 in a Heritage Auction. This Proof Nickel/Dime mule is unique and in a class of it's own.

This U.S. proof striking of a muled Nickel obverse die and Dime obverse die or hub on a large proof planchet is unique and one of the most spectacular mint errors or die trials ever discovered. It is a combination of rarity, fantastic eye appeal and numismatic significance. Whether or not it is a mint error or a die trial adds mystique to an already unique and spectacular numismatic rarity.

Exotic and Intentional U.S. Error Coins In The Marketplace One of the most controversial categories of U.S. coins are mint errors. Many dealers and collectors, as well as coin auction houses, buy, sell, trade and auction many rare, exotic and unique major mint errors. Obviously, some of these defy logic and were intentionally created and taken out of the Mint. In the early 2000's, a group of several hundred U.S. error coins were found in a safe-deposit box. Fred Weinberg purchased this group which included coins struck for proof sets and also coins struck for circulation. This group was auctioned by the California State Controller's Office of Unclaimed Property. The U.S. Secret Service inspected and released this collection to the State of California determining that it was legal to own. The State of California then auctioned the collection and the rest is history. Another example of U.S. error coins escaping the Mint occurred in the 1970's. A hoard of proof error coins were smuggled out of the San Francisco Mint inside the oil pans of forklifts that were being serviced outside of the Mint. This topic was discussed in the June 6, 2022 Issue of Coin World, which covered Fred Weinberg's account of this story. The Coin World Managing Editor concluded: Obviously, the marketplace accepts these coins, and some collectors are happy paying thousands of dollars for coins that show every indication of having been created through illegal means. In Episode 11 of the PCGS video series Slab Lab, Seth Chandler interviews Fred Weinberg. In part 2 of the interview, Fred explains in detail why mint errors that are decades old are not recovered by the U.S. Mint. Fred's recollection of conversations in his office with the Chief of the U.S. Mint Police are extremely insightful and explain why the Mint doesn't attempt to recover error coins from decades ago.