1977 Kennedy half 11.55 grams?

Discussion in 'Error Coins' started by Dan Galbato, Sep 22, 2023.

  1. Dan Galbato

    Dan Galbato Active Member

    Hello members, I’m new here and want to learn. I have read about a Kennedy half, Denver mint that was an error weighing 11.5 grams. I found a 1977 Kennedy, no mint mark, that weighs 11.55 grams. Is this a silver over copper error? Thanks in advance.
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  3. paddyman98

    paddyman98 I'm a professional expert in specializing! Supporter

  4. Dan Galbato

    Dan Galbato Active Member

    Paddy, thanks for your help. Maybe I’m stating the way this was struck incorrectly. The half looks normal and should weigh 11.3 grams as most do. My half weighs 11.55 and was made on either a silver or possibly a nickel planchet? I saw the 1977d example and asked myself if the same error, however it was struck, could be made at the Philly mint? I read the only way to check out the metal was to have a gravity test. I’m totally confused here. Lol
    SensibleSal66 likes this.
  5. -jeffB

    -jeffB Greshams LEO Supporter

    It's not impossible, but it's really unlikely. I think it's more likely to be a standard half that's been plated, or struck on a clad planchet made from over-thick stock.

    Clear photos of the coin would be helpful. Especially helpful would be an edge-on photo showing the coin and a normal half, either stacked or side-by-side.

    I think a specific-gravity test would be challenging, as the density difference between 40% silver-clad and cupronickel-clad is fairly small. An XRF (x-ray gun) test would probably be definitive.

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  6. SensibleSal66

    SensibleSal66 U.S Casual Collector / Error Collector

  7. SensibleSal66

    SensibleSal66 U.S Casual Collector / Error Collector

    Here's weight chart. Please click to enlarge.
    US Coins, weight Composition and Tolererances.jpg
    -jeffB likes this.
  8. Spark1951

    Spark1951 Accomplishment, not Activity

    @SensibleSal66 …I believe this data chart has incorrect values…discovered a month or two ago. I just refer folks to a Yeoman Red Book…Spark
    @Dan Galbato
  9. Dan Galbato

    Dan Galbato Active Member

    My half IMG_2173.jpeg IMG_2169.jpeg IMG_2168.jpeg IMG_2172.jpeg IMG_2173.jpeg IMG_2168.jpeg IMG_2169.jpeg
    -jeffB likes this.
  10. l.cutler

    l.cutler Member

    The copper core is clearly visible, I'd have to say just struck on a slightly thick planchet.
    71Avalon, -jeffB and Dan Galbato like this.
  11. Dan Galbato

    Dan Galbato Active Member

    Thanks for your help.
    thanks for your thoughts. You’re most likely correct but it’s strange that the half with a thicker copper planchet is only 11.3 grams and the half shown on the left has a thinner copper appearance and weighs 11.55 grams.
    what I see is a thicker silver top surface with a thinner amount of copper between top silver surfaces? I’ll try adding one more image to show what I’m seeing. TKS
    l.cutler, 71Avalon and -jeffB like this.
  12. Dan Galbato

    Dan Galbato Active Member

    IMG_2174.jpeg The coin on the left has a thinner copper core and weighs 11.55.
    -jeffB likes this.
  13. -jeffB

    -jeffB Greshams LEO Supporter

    Yeah, there's some suspect data in the chart posted above -- but that +/- 0.454g tolerance matches what I've seen elsewhere, and indicates that an 11.55g clad half is still well within tolerance.

    The apparent thickness or thinness of the cladding layers you see on the side varies widely; it all depends on how the metal was dragged across the edge as the blank was punched from the stock strip. So, yes, you're seeing different layer thicknesses on the edge, but no, that doesn't mean the layers are really different thicknesses -- they're just smeared at the edge.

    The photos you're posting (excellent photos, btw!) look to me like a completely standard clad half dollar. If it were struck from silver, it would almost certainly have a distinctly different color -- I've only ever seen one or two 40% halves that look that much like clad.
    l.cutler and Dan Galbato like this.
  14. Dan Galbato

    Dan Galbato Active Member

    Love this place! Great learning experience. Thanks to all. I have several additional questions to ask regarding different coins I’ve collected over time and look forward to coin school!
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