What is this purplish black stuff?

in Q & A Forum
I noticed it when I bought the coin but I still can’t figure out exactly what it is.
It looks kind of like what happens when you put gold testing acid on pure silver but I don’t think that’s what happened since it would be extremely dumb to put acid on an ancient coin.
Anyone have any ideas?
0
Comments
Since it's in a holder, what's the grade? How long has it been encapsulated? Peace Roy
BST: endeavor1967, synchr, kliao, Outhaul, Donttellthewife, U1Chicago, ajaan, mCarney1173, SurfinHi, MWallace, Sandman70gt, Ricko, mustanggt, Pittstate03, Lazybones, Walkerguy21D, coinandcurrency242 , thebigeng, Collectorcoins, JimTyler, USMarine6, Elkevvo, Coll3ctor, Yorkshireman, CUKevin, ranshdow, Jzyskowski1, CoinHunter4, bennybravo, Centsearcher, braddick, Windycity, ZoidMeister, mirabela, JJM, RichURich
Here is the grade. I’m not sure how long it’s been encapsulated. I just won it at auction.
Possible just some silver tarnish that has started to appear. Silver is quite reactive and when it is exposed to air, dark silver oxide will start to appear which is what I think is on the coin.
Young Numismatist/collector
70 Positive BST transactions buying and selling with 42 members and counting!
instagram.com/klnumismatics
Looks like tarnish from the picture.
Not bad for a 2000 year old piece. I do not collect ancients but fashionated by them
Correction: 2,400 year old coin.
I know you were close but 400 years is still a long time xD.
Heck, America isn’t even 300 years old.
It’s crazy how many empires have come and gone while this coin survived it all in MS condition.