The Great Depression of 1984

[joel]

I don't remember seeing one like this before, but there's a lot of stuff I don't remember lately. Anyhow, what causes this? Is it some kind of chemical change going on behind the MM? Thanks for your help.

[Maineman750]

It's called zinc rot, and is quite common on zinc cents behind the mint mark, although I'm not exactly sure why.

[willbrooks]

I love Coop's collage of this. I used it to illustrate zinc rot in the glossary. I always get a chuckle out of it.

[Frank]

Awesome, I've been wondering about that myself for a while. Learned something new again here!!

[willbrooks]

I'm with Roger that the mint mark is the most common place to see this. I have a plausible explanation as to why this is the case. When relief is struck into a flat surface, the overall surface area is increased, thereby stretching the plating. In this era, the mint mark was punched by hand into the die. I believe that in many cases, the depth of the punching was deeper than the rest of the incuse elements on the die. Thus, when the die struck the coins, the excessive difference in the relief was enough to compromise the plating on the coin. Once compromised, the zinc core corrodes very quickly due to the exposure to the environment.

[joel]

I'm with Roger that the mint mark is the most common place to see this. I have an explanation as to why this is the case. When relief is struck into a flat surface, the overall surface area is increased, thereby stretching the plating. In this era, the mint mark was punched by hand into the die. I believe that in many cases, the depth of the punching was deeper than the rest of the incuse elements on the die. Thus, when the die struck the coins, the excessive difference in the relief was enough to compromise the plating on the coin. Once compromised, the zinc core corrodes very quickly due to the exposure to the environment.

That is a deep thought, Will!! Seriously, I appreciate that you took the time to explain how this may happen and I find it to be very logical. Thanks, Larry

[jfines69]

The early Frankenzincs is what I have seen the most of these on - mid 82 - 89 with mid 82 - 84 being the worse... There was an issue with the split plating on all of the devices when the plating stretches out... Lots of zinc rot and craters left on the coins.!!!