I have some quarters and other coins that I have found to have turned black, for example, this Morgan dollar- I don't believe that it is toned, so does anyone know why this happens to some coins with F+ detail?
If not blatantly painted black, then oxidation plus oils in human skin from handling, dirt and grime all combined.
Silver and sulfur REALLY like each other. And the resulting silver sulfide is black. That's why housewives spend hours removing tarnish from their silverware. How do you prevent this from happening? Well, you really can't; mostly you can just slow the process way down. These three are probably the most important: -- Store coins in holders that are archival quality. -- Store coins in holders that are nominally airtight. -- Store coins in places that have constant temperature and humidity conditions.
Thanks everyone. I bought this one black because it had the best detail out of anything so I am happy with it. It was only $19.
Some of the yellowish colored coin holder paper envelopes contain sulphur in the paper and shouldn't be used to store silver coins in. Use plastic or cardboard holders.
I bought a semi key date Barber dime that was stored in a small manilla envelope for probably a few decades. The sulfur in the envelope turned it black, but it still graded ok.
Yes - sulphur just reacts with the silver turning it black. It doesn't deteriorate the features of the coin at all.
As long as you don't try to remove the toning you're okay. UNLESS The toning is SO dark that graders are afraid it's covering up something.
Oh but it does. Toning never completely stops and eventually it will literally eat away a coin until there is nothing left. Of course that would take centuries. And there are many, many, silver coins that were toned black, and when dipped to remove the toning, pitting where the toning ate into the surface of the coin became visible.
