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. Jon Sullivan, a coin dealer specializing in mint errors, sold the only known Bicentennial quarter struck on a dime blank in PCGS Proof 67 in the low 5 figure range.
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.
A very small group of Proof errors recently came from a collection that was auctioned by the State of California. 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 it has been dispersed since the sale.
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.
Below is the unique Proof Bicentennial Quarter
struck on a dime blank that Jon Sullivan
privately sold in the low 5 figure range:
Also 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.
Proof Errors are featured in the NLG award
winning book, World's Greatest Mint Errors.