For one thing, it still had intrinsic value, being made of .90 silver. For another thing, it was a work of art. I still have a few in my boyhood coin collection, stored away somewhere.
It is pretty enough that some think it is a Saint-Gaudens, but, in reality it is the work of Adolf Weinman, another American sculptor of considerable renown. Weinman also produced the most beautiful U.S. silver coin of all, in my opinion - "Walking Liberty" - which appeared on half-dollars 1916-1947. (If you clicked on the link and are confused at the date of issue on the illustration, you should know that the U.S. Mint still produces many of these coins annually for bullion-traders, not for circulation.)
The most beautiful U.S. coin of all time, gold OR silver? The Saint-Gaudens Double Eagle, bar none. The Double Eagle is a gold coin with a face value of $20. A $50 face-value version (1 oz.) is also minted for bullion-trading purposes now. Of course, face-value means nothing nowadays, since you would hardly take one of these coins out shopping. The gold spot price for one ounce on 28 October 2010 was $1,388. Incidentally, a 1933 Double Eagle is also the most valuable coin in the world today, one at auction in 2008 fetching just under eight million dollars.
But back to the "Mercury Dime."
Everyone calls it a Mercury Dime because everyone, myself included, has always assumed the face on the obverse of the coin is that of the Roman messenger-god Mercury. Those pesky winged helmets again. But au contrare - further research leads to the discovery that it is really the image of the mythological goddess of liberty, and is properly called "Winged Liberty."
This (of COURSE) brings us to the subject of Phrygian caps. It's not a helmet at all, by gosh, and you can plainly see that it is not a helmet if you study the image of the same lady, Walking Liberty, on the above linked half-dollar. No, sir, it's a cap. A Phrygian cap. Phrygia being the central part of Anatolia, which is itself the western two-thirds of the Asian part of Turkey.
But you knew that. Or, at least, I'm sure Soubriquet did. Soubriquet knows all.
Suddenly I've run out of things to say about the Mercury Dime. ::Scratches head and slowly walks away::