How was this Roman coin made?

Discussion in 'Ancient Coins' started by Neal, Dec 14, 2017.

  1. Neal

    Neal Well-Known Member

    Back in 1963, when I was only 13, I bought my first Roman coin, by mail order, and received a very corroded 14mm bronze of Constantine II. I "improved" it by treating it to remove the corrosion, which left a very porous coin with a few large holes. In the bottom of the larger holes there was a dark layer, which I eventually learned was a layer of lead. My questions are, first, how common was this practice, and second, how could they make the planchets with a lead center? I would not think they would have had the technology to inject it, like a jelly donut, and because lead melts at a lower temperature, a lead blank could not have been dipped in hot copper. Would they have wrapped and hammered it? But that would have squirted the lead out like stepping on a tomato. I've wondered at this for over half a century.
     
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  3. Neal

    Neal Well-Known Member

    Forgot to post the pictures: Constantine II obv.jpg Constantine II rev.jpg
     
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  4. LaCointessa

    LaCointessa Supporter! Supporter

  5. David@PCC

    David@PCC allcoinage.com

    Last edited: Dec 14, 2017
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  6. Neal

    Neal Well-Known Member

    My coin certainly is made of bronze, and I would have thought that anyone debasing it would just mix the lead in with the melted bronze. But there it is, for whatever reason, a plug of lead in the center of this otherwise bronze coin. Perhaps they wanted it to have more weight but look like higher quality bronze. It is not as obvious in the picture, but in 1963 when I first discovered it, I thought the dark center was some kind of dirt or residue, so I took a pin and scraped it lightly. You can still see the scrape marks in the picture. To my surprise, the dark material was a soft, shiny metal where scraped, but eventually darkened back, as lead does. Unlike our clad coinage, there is no sign of the lead around the edge.
     
  7. David@PCC

    David@PCC allcoinage.com

    I can't answer other to say the weight of a base metal coin wouldn't matter in this case, there would be no reason I can think of to have a lead core. I would think it would be more valuable to make seals with it but my knowledge is more with coinage. Typically any coin from this period just crumbles or breaks up when severely degraded. I have handled and cleaned many many thousands of these and never came across what you are describing. If it is what you say it is, maybe donating it to a researcher would yield some new discoveries?
     
  8. Severus Alexander

    Severus Alexander Blame my mother. Supporter

    Very interesting! The only thing that occurs to me is that it may have once been gilt, but why do this to a GLORIA EXERCITVS? Maybe @Valentinian can make sense of it...
     
  9. Valentinian

    Valentinian Supporter! Supporter

    There are far more coins with lead globs in them than most collectors think. We don't want them so dealers don't buy them to put on vcoins or take them to shows. You will find some in very large lots that have had good coins removed. I have inspected the collection of a old friend who, years ago when viewing very large lots, purposely selected lousy coins (mostly 4th century Roman) with lead globs in them to illustrate the phenomenon. He had hundreds (all worthless, from my standpoint), but I'm sure they cost almost nothing.

    The government issued coins with some lead in them. Cope analyzed many tetrarchal and Constantinian-era coins and some had over 10-12% lead. Sometimes the lead mixed well, sometimes not. It is small percentage of coins that dramatically show when the mixing was poor. When a glob a lead was in the flan, sometimes it corroded away. (Usually in the process it turns white first.)

    DiadumenianLaodicea.jpg

    This is one of the finest coins I have seen with obvious lead globs. It is an AE30 Diadumenian (217-218) from Laodicea ad Mare in Seleucia Pieria. At 11:00 on the obverse and elsewhere you can see the white and empty pockets where lead was and is now missing.

    I think the explanation of the OP coin is that it was made of poor metal with some lead globs in it, which, over time, corroded away. The fact that particular example had lead in the center is coincidental.
     
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  10. David@PCC

    David@PCC allcoinage.com

    Well there ya go, learn something new everyday. So it's not a lead core per say, just that there are some lead lumps that are exposed. Makes sense since both have different melting points.
     
  11. Valentinian

    Valentinian Supporter! Supporter

    If you want to learn more about metallurgy of ancient coins, fill your bookshelf with these:
    MetallurgyBooksPhoto.JPG
     
  12. Mat

    Mat Ancient Coincoholic

    Interesting, and a look like that, I would assume its a form of BD, even though it isn't green.
     
  13. red_spork

    red_spork Triumvir monetalis Supporter

    Many Roman Republic bronzes were made with a leaded bronze alloy as well:
    20160515234228-51f041de-me.jpg

    The white occlusions on this coin are lead and have the look of oxidized lead as opposed to BD.
     
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  14. Valentinian

    Valentinian Supporter! Supporter

    It does not have the characteristics of BD. It is just the lead component corroding and sometimes falling out of the coin.
     
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  15. Neal

    Neal Well-Known Member

    Thanks to all who have commented. Especially to Valentinian. Thank you for taking the time to give such a full explanation! After 54 years of wondering, I finally know the answer!
     
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