This unusual and precious 1970-S Proof quarter stamped on a 1941 Canadian quarter planchet stands out. This coin, made by accidentally using a foreign planchet, sold for $35,000 at auction.
Due to a manufacture fault, the 1970 Double Die Obverse error duplicates the coin's date and text. The doubling effect might blur the coin's writing and numerals.
A partially full die causes a weak strike, causing the 1970 Scarface error, or “thin quarter error.” This mistake is commonly depicted as a thin, vertical line on George Washington. While less precious than the DDO, it can be valued $30–350, depending on condition.
Before striking, part of the blank metal disc used to manufacture the 1974-D coin was trimmed off. It leaves a conspicuous gap on the coin's edge. These errors can fetch $20 to $100 or more, depending on clip size and coin condition.
Several 1976 Bicentennial quarters were inadvertently struck on 40% silver planchets instead of copper-nickel. Highly rare transitional mistakes can sell for over $1,000. Check for silver content in a 1976 quarter with a “S” mintmark to see if you struck gold.