Ron Guth:
The 1842 Dime is a fairly common coin which behaves (if coins could behave) like the 1841 and 1843. These three dates have nearly identical total populations and there are similar quantities of Mint State examples of each date. The typical Mint State 1842 Dime is MS63 or MS64. Gems are very scarce and only a handful of MS66 examples sit atop the Condition Census. The strike quality of this date is good, though the stars, denticles, and lower right wreath are sometimes weak.
Researcher Gerry Fortin has identified eight different varieties of the 1842 Dimes, one of which was used to strike Proof coins.