Interesting also on the clad 40% silver half. The outer is 80% silver and 20% copper and the inner is 79.1/20.9 opposite. I had to rethink the math to come up with 40% silver. I think they used the ASW of the 90% half to come up with the ASW of the 40%. But when I did it that way it still did not come out to 40%. Oh well !
Also just to chime in, The mintmarks were on the rev. from 64 through
67 and on the obv. 68 thru 70. Wonder if there where any MM errors.