Newfoundland 1882-H 50 Cent Planchet Flaw?

Oops... Here she is.

It is much more common to find planchet lamination flaws in modern base metal coins, than silver coins of the 19th century, but it does happen.
A lamination flaw is usually the result of an inpurity being rolled into the strip of coinage metal before the blanks are cut out.
Sometimes the flaw will not show up for decades, until there has been sufficient chemical deterioration around the rolled in impurity, to enable a thin sliver of metal to appear on the surface of the coin, sometimes the lamination will show up on a freshly struck coin.

I note that in this coin, a small piece of metal on the rim has already spalled off. The rims of a coin are far more subject to impact damage than the rest of the coin.