So I had a mediocre day at work today, at best, so I accidentally stopped at one of my favorite watering holes to take the edge off. After taking the edge off (four, maybe five pints - who's counting?) and paying my bill, I got my change, in which was included a single US 2016 penny, covered in what looks to me like a really bad case of Bronze Disease. I happened to be carrying around a couple of recent purchases - a Gordian III sestertius and a pretty Faustina II as today, so I was alarmed. It was like I got a plateful of plague. (And this justifies my posting this in the Ancient Forum). I didn't think there was anything "bronze" about a 2016 penny. I also thought BD took a gazillion years to form. Huh! After carrying it home in quarantine in my shirt pocket, I left it out on the porch to see what happens to it.
The greenish is probably copper compounds, but the white does look like zinc chloride which is corrosive , but very soluble in water , so try it~ rinse well, and if it removes it, you can remove it from the other coins the same way and then dry. The copper is tougher, but your coins are likely safe.
