Mercury Head Dimes (officially "Winged Liberty Head Dimes") were produced for almost 30 years.  They were composed of 90% silver and designed by sculptor Adolph Weinman.  The "heads" side pictures a profile of the allegorical figure Liberty wearing a Liberty cap.  The artist added wings to the cap to symbolize "liberty of thought," however, this caused many people to mistake the figure for that of the Roman god Mercury, giving rise to the dime's common name.  The "tails" side of the Mercury Head Dime shows a fasces, a Roman symbol representing the power of law and government, surrounded by an olive branch, symbolizing peace.  The mint mark is on the "tails" side, while the artist's initials are on the "heads" side.  The design remained the same until 1945, when the Mercury Head Dime coin was replaced with one honoring recently deceased President Franklin D. Roosevelt.