Mintage error?

Sitamoia

I came across this yesterday in my change. What do you think, mintage error or burn/melting by someone?

coylemj

Sitamoia wrote: »

mintage error or burn/melting by someone?

or someone hit it with a blunt object?

Sitamoia

It's raised on the coin, it's like metal dripped onto it or something.

Blade

This is most likely what's known as a lamination error. The Euro coppers are made from copper covered steel, the process involves sandwiching a sheet of steel between two copper sheets. They are bonded together by a process called "explosive bonding", sometimes the layers don't bond properly but are not noticed at this point. After this the blanks are punched out and go on to the minting process. It's usually after the coin is struck that this weakness in the bonding shows up in the form of this bubbling effect you see here, where the copper separates and bubbles up from the inner steel core.

It is however also possible to get this effect by applying the heat to these coins yourself, so not of much numismatic interest or value.

Sitamoia

Thanks for your help. I'll hold onto to anyway, just thought it was interesting.