Owner Comments:
1979 was the first year of the Susan B. Anthony dollar series with a mintage of 3,677,175 proof coins. Two varieties emerged in 1979. One dealt with the "S" mintmark being filled or blobby (Type-1, "Filled S"), and the other being clear and more defined (Type-2, "Clear S, Rounded"). There is no clear count of how many Type-2 coins exist, but they trade at a premium more than double that of the Type-1 coins.
Another variety for the Philadelphia produced circulating coins has the date appearing on the obverse far from the rim (Narrow Rim, Far Date), while the other has the date appearing near the rim (Wide Rim, Near Date). Over 360,000,000 Philadelphia circulating coins were produced, so the variety here is less significant.
Ebay auction purchase from L&C Coins, 04/09/2015, $59.15