Proof 1776-1976 S Bicentennial Quarter
Double Struck on Struck Roosevelt Dime

Unique Discovery Coin


This is the only known proof Bicentennial Quarter double struck over a struck Dime. It is also the only known double struck U.S. proof coin overstruck on any struck coin.

The 1976 Proof Bicentennial Quarters were struck at the San Francisco Mint. 1976 Bicentennial off-metal mint errors are very rare in every denomination struck for circulation. In proof, they are prohibitively rare with only 4 proof Bicentennial off-metal double denominations known on any denomination. There are (2) Bicentennial proof quarters struck over struck cents known. There is a just discovered and unique 1976-S Bicentennial quarter struck over a struck 1967 dime. And now this new discovery of a 1976-S Bicentennial quarter double struck on a struck dime.

This unique discovery mint error cannot be compared to previous sales and auction records but here a few related mint errors to give an idea on its rarity and value. In a Heritage auction, a NGC Mint State 64 Bicentennial Quarter on a Dime blank sold for $6,900. Also in a Heritage auction, a Bicentennial quarter struck on a struck Dime in PCGS Mint State 62, sold for $9,200.

Proof coins are struck by technicians who hand feed the blanks into special presses. They are produced, examined and packaged using extreme quality control. It is very unusual to find major proof errors. A few broadstrikes, off-centers, double strikes (in collar) and off-metals have been known to be found in sealed proof sets. Proof errors are aggressively sought after by many error collectors.

This unique mint error offered here was just discovered and was authenticated and certified Proof 67 by PCGS. It was preserved in amazing condition with phenomenal detail remaining from both of the quarter die strikes. There is some detail remaining from the original dime design, which is noticeable underneath the two quarter strikes. I've never seen a proof overstruck coin with anywhere near this amount of detail creating a visually stunning and incredible multiple mint error.

This discovery mint error is fascinating since it combines rarity (unique), quality (Proof 67), history (Bicentennial one year only design) and spectacular eye appeal and detail from the strikes. This enigmatic and unique U.S. proof mint error belongs in a major collection of the finest error coins or in a collection of Bicentennial coins.






For comparison, below are the two famous and enigmatic Washington Quarters from the San Francisco Mint struck in Proof, over a U.S. Silver Barber Quarter (1892-1916) and over a 1941 Canada Silver Quarter. These were both featured in a TV interview I did with Fox News. These fascinating errors went "viral" and were featured in USA Today, London's Daily Mail, AP News, Coin Week, New York Post, Newsmax, NBC News, Numismatic News, Time Magazine and on Maria Bartiromo's TV show.




Intentional Errors

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.

Proof Errors are featured in chapter 21 of my
NLG Award winning book, World's Greatest Mint Errors: