1909 VDB Question

I've seen this posted here once before, perhaps in the last 4 months or so. Have you done a Search to see if you can locate information?

I'm fairly sure it was under Modern especially because it is a 'modern' coin. I don't recall the details other than the poster was wondering the same thing - what is that stuff. I do recall it was an LWC and it was also the reverse. Not sure on the date though. I only followed the thread briefly so I don't know the final conclusion rendered (or if one was rendered). I'll follow it this time though - I may have a similar specimen floating in my hoard.

CC - from sitting in a plastic folder? Is it the plasticizer that reacts with the copper? Thanks.