Whether or not a coin has been circulated affects its value as does the coin's condition and its mint mark. Silver dollars are usually purchased either for their value to collectors or for their silver content.
Mint marks are the tiny letters or numbers found on a coin. They are there to denote the different mints of a coin, and some are more valuable than others.
When determining the condition of a coin, collectors examine the wear on its surface. An uncirculated coin will have no wear to its surface because it has never been used as currency, and a coin in extremely fine condition will be missing a very minute amount of detail from its face. A coin in fine condition will have noticeable wear on its face and a coin in good condition will be very worn on all its raised parts.