Yea, that "D" or "S" mint mark on the reverse always gives it away if you didn't notice the color change. MM were put on the obv in '68 til today. And to think when I started CRH I use to check each date looking for silver, until you guys ( the seasoned veterans ) convinced me what to look for by way of RIM CHECKING. Now I can rim check a box in under 45min.
Rim checking is not failsafe! Many silver dimes have a dark rim.