Wrong Planchet Errors: When Rare Quarters Get Struck on Thin Dime Stock
By Alexander Ross
The Denver Mint production runs of 1970 produced several verified batches of this specific mistake. Millions of quarters left Colorado that year, but an unknown run of blanks came straight from cupronickel coils intended for dimes. The 1970-D quarter error remains one of the most widely documented instances of this manufacturing breakdown.
Spotting an authentic example requires careful observation of the rims. Coin dies rely on die-space displacement. As the obverse and reverse dies push into the metal, the displaced mass pushes outward into the coin's perimeter, forming a raised, protective rim.
On a quarter struck on dime stock, the missing 0.40 mm of thickness means the displaced metal never reaches the deepest parts of the rim profile. The coin displays flat, mushy edges. The lettering along the rim, such as "LIBERTY" and "UNITED STATES OF AMERICA", often merges softly into the fields rather than standing out with sharp, perpendicular bevels.
Reeding along the edge provides another definitive diagnostic check. Standard quarters carry 119 reeded grooves pressed by the collar die under immense pressure. On thin stock errors, the reeding looks weak, faint, or partially absent near the center of the edge.
Alexander Ross has covered the video game industry for a decade, writing deep dives on game design, esports tournaments, VR developments, and gaming culture.
