Machines that make coins do so with tens of tons of pressure from incredibly high-speed mass production coining presses that use brittle steel dies on all manner of planchets, some with thin-plating zinc. As working dies reach the end of their lives, or as machines rattle from all that pressure, these common errors occur on different denominations (consult the Illustrated Glossary for definitions):
- die chatter
- die chips
- die cracks
- die gouge
- delamination
- die dent
- die deterioration
- filled mint marks
- machine doubling
- plating blisters
- split plating
- struck through
These are only worth a few dollars, if you can find anyone who wants to buy them. Go to the “sold” button on eBay and you’ll see the results.
Here’s some die crack examples:
How, specifically, do these errors happen?
Die Deterioration, Chips, Cracks, Gouges, Die Chatter: These occur when working dies–minting hundreds of thousands of coins–become worn from the pressure and brittle. Minute pieces of the die break or crack from the pressure, and metal fill the voids with raised appearance.
Machine Doubling, Die Deterioration Doubling, Die Dents: These are mechanical errors as opposed to mint errors. They occur when the die bounces or moves during coining. The result is not raised but shelflike.
Filled Mintmarks: Until the late 1980s, mintmarks were punched directly into the working die. This was an extra step back then, so not only do the mintmarks appear in different places but also, depending on the punch, were susceptible to clogging.
Plating Blisters, Split Plating Doubling: After 1982, cents were made of zinc. these are caused by trapped gas or thin copper plating breaking over the zinc core, often mimicking doubling.
Roller Marks: These resemble the mint error on cents called “woodies” (again, consult the glossary) that look like wood grain due to improper annealing. But roller lines are caused by uncleaned rollers used in the minting process–another example of mechanical error.
Delamination: This happens a metal alloy does not cohere properly, resulting in the surface peeling off. These are common in older coins, especially zinc cents.
You do not need a coin microscope to see these. Magnification makes these common errors look significant; they are not. At best these sell for a few dollars on eBay.
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