NGC 50c 1973-S Proof Kennedy Half on Quarter Planchet PF67+ Cameo

NGC 1973-S Kennedy half struck on a  clad quarter planchet. The coin is struck on the much lighter quarter planchet with a weight of only 5.6 grams, and also much of the outer lettering is missing. 

Wrong planchet error Kennedy halves are rare on proof Kennedy halves, and there are only small number of known examples on quarter planchets. We can only find 3 examples in auction archives, three that we have handled, and have seen just a very few others elsewhere. Maybe 10-12 are known would be our estimate. 

NGC PR67 Cameo with frosted cameo devices and mirrored fields.