1970-S Proof Washington Quarter
Struck on a Silver Barber Quarter
NGC PF 65
1 of 2 Known
SOLD

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.

Proof Washington Quarters struck in 1970 by the San Francisco Mint were clad. This 1970-S Proof Quarter was intentionally over-struck on a Silver Barber Quarter and is one of two known. This mint error was originally discovered in the group of San Francisco Proof Errors that was auctioned by the State of California. There is some detail on both sides showing the design of the Barber Quarter. This is one of the most famous U.S. Proof Major Mint Error ever released from the San Francisco Mint.





These 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.

Featured on the cover of Mint Error News Magazine Issue 37

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:

The Mint Error News website has a 69 page report of coins struck by the U.S. Mint for foreign countries. It is the most comprehensive report available anywhere. Click here for a pdf of the 69 page report.



Click here for a pdf of the 69 page report.