1966 Roosevelt Silver Dime

How do you know it is silver?

They were still producing silver dimes in 1966 so a silver '66 dime is quite possible.

They are merely unknown.

Clad king...silver in 66, really?

That would be a amazing fine..a64 silver planchet wandering among the 1966 world of cladites would be cool and possible

Yes. There was a law passed in the autumn of 1964 that froze the 1964 date in perpetuity. The intention was to start minting the coins in base metal and destroy any investment value by keeping the same date and eliminating mintmarks. But in the summer of 1965 the coinage act of 1965 was passed which changed this. The '64 dates were still being minted at that time (1965) but the new coins would be made with the 1965 date forever and silver would continue being minted with the '64 date. The thinking was that if people believed the governmebt would continue to mint silver there was no point in hoarding it. This didn't work and new silver was sucked up even faster than old silver so they stopped the '64 date entirely in February of 1966. The coinage act of '65 did give the mint direction discretion to change the '65 date if he determined the coin shortage was eased and even allowed the return of mintmarks at his discretion. Normal dating resumed in mid-1966 and mint marks returned with the 1968.

This provided huge opportunities for all sorts of mules and errors and many exist. There are silver quarters struck from clad dies and even several 1965 silver quarters and dimes. There's a laundry list of such oddities.

No 1966 silver dime is known and is improbable to turn up after so long. Such a coin would be worth several thousand dollars, I should think.

If I'm not mistaken Denver was striking silver dimes into 1966. It was the last 90% silver denomination still in production during the transition.

Learn something new every day

It would also help to get the weight of the coin in grams going out 2 decimal places.