The Mercury Dime features a battle-ax to signify military readiness, placed next to an olive branch to express hope for peace.
Mercury Dimes show horizontal bands holding together the rods. If these rods are fully separated and rounded they can generate significantly higher prices than coins of the same date and mintmark.
Rare Mercury Dimes were minted on the following key dates, the letter stands for the mint:
Mercury Dime 1916-D Mercury Dime 1921 Mercury Dime 1921-D Mercury Dime 1942 / 1-D
Here are some rare Mercury dimes for sale on ebay. Blacklisted sellers are excluded.