15 rare state quarter errors. When compiling the list of the rarest state quarter errors, we considered factors such as mintage mistakes, market value, auction history, and collector demand.

NEW YORK, Nov. 7 (UPI) -- Some of the U.S. state quarters released in the past decade have become valuable because of minting errors, a new book says. David L. Ganz, author of "America's State ...

Here are some signs that you might have an experimental planchet 1999 Georgia quarter error: Weighs between 5.9 and 6.3 grams on a coin scale, which is more than the 5.67 grams for a typical ...