Quote:
It is generally believed that lamination errors are caused by contaminants in the alloy that cause the metal to separate along the horizontal plane.
Above is a quote from the link below explaining how lamination errors happen:
http://www.error-ref.com/lamination-cracks/They are quite common on the
Wheat cent series. Finding a nice example can bring a modest premium. Nice find

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-CH27
Collector of U.S. Coins, Varieties, and Colonial Coinage