found a 1971 D half in a roll. it looks like silver and weighs 11.8 grams. that is more than clad or 40% ones. could it be from a proof set? thanks..........
If it looks like silver then more than likely it is plated. There is a very very minute chance that it was accidentally stamped on a silver planchet, but the odds on that are astronomical. There were no 1971 halves (mint set, proof or otherwise) purposely stamped on silver planchets.