The 'S' stands for the mintmark for the San Francisco mint.
dime = 10 cents
The 1945 nicro S Mercury Dime is 90% Silver Mercury Dime that was minted in San Francisco. San Francisco used different types of punches in 1945.
Mercury Head dimes dated from 1940 to 1945 regardless of mintmarks (if any) are very common. Coins in average circulated condition have a retail value of $3.00
June 4 2011 A 1942 Mercury dime with no mint mark in MS-65 condition is worth an average of $22 One with a D mintmark is worth an average of $22 in MS-65 condition. One with a S mintmark is worth an average of $25 in MS-65 condition.
That's not a mint mark. It's the monogram of the designer A.A. Weinmann. The West Point Mint did not open until the 1980s and only strikes commemorative coins and cents. Mercury dimes had their mint mark in the space to the right of the word ONE on the dime's back. For a 1942 dime it will either be blank (Phila.) or have a small "S" for San Francisco, or a "D" for Denver.
The 1894-S dime is considered the rarest Mercury dime, with only 24 known to exist. This coin is highly sought after by collectors and can fetch a high price at auctions.
The Mercury Dime was minted in all three mints, Philadelphia, Denver, and San Francisco. Not all three mints minted the Mercury dime every year. There were no Mercury dimes from the Denver mint in 1923-D or 1930-D. If you ever see one, it's a counterfeit coin. There was never a 1934-S dime minted either.
I also have a 1917 s mercury dime it appears to hace dubbling on the B ,,,as most will tell tou uts worth as much as someone is willing to pay!
That would be the 1916-D with a mintage of 264,000. However, the 1941/1942 overstrike error with an unknown mintage is also in demand by collectors. More information can be found at this website : http://coins.about.com/od/coinvalues/qt/mercury_keys.htm
All "Mercury" dimes (aka Winged Liberty Head Dimes) struck at the branch mints of Denver (D) and San Francisco (S) have their mint marks near the bottom of the reverse, just to the right of the word "ONE".
The size of the mintmark. The micro S is about half the size of the regular one.
4-4-11>> Mercury Head dimes dated from 1940 to 1945 regardless of mintmarks (if any) are very common. Coins in average circulated condition have a retail value of $3.00