The die for a 1900 Indian-head penny was used on a gold planchet, resulting in a pure gold penny.
Not all valuable coin errors are old. In fact, one of the error coins that's worth the most dates from 1999.
Like the 1900 example, a gold planchet somehow ended up being struck with the dies for a 1905 penny.
Another modern coin error that collectors prize, the 2001-D Lincoln cent mule is rare and worth a lot.
Sometimes, an error doesn't involve the wrong planchet or two different dies being used.
A planchet for a Sacagawea dollar and the "tails" side of that coin were stamped with the profile of George Washington on the "heads" side.
One of the greatest coin errors isn't even a mule or a planchet error is a die that struck the planchet off center.
The buffalo nickel is an icon of US coin history, and it's always silver in color. Make that almost always.
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