So this coin is a blast from the past. Not only because it is from Constantine I but also because my dad bought it when my parents came to visit me when I lived in London back in 2002-2004. My dad bought this at a small coin shop that was across the street from the British Museum. It was totally forgotten about by them and me until my son and I started getting into ancients. Well my parents just arrived at our house for Christmas and brought this for us. I was hoping it was minted in London since that would make it all the much cooler and we do not yet have a coin minted in London. Unfortunately, it isn't. FFIVN and I have made as best an identification as we can. We aren't able to completely make out the mintmark. Constantine AE follis. 320-321 AD. Obv: CONSTANTINVS AVG, laureate head right Rev: DN CONSTANTINI MAX AVG, VOT XX in wreath with star in badge at top of wreath. Mintmark TSΓVI. - This we aren't not 100% sure on. TS can be made out but not sure of the third character. In it's original flip
Touch it with a toothpick and see if it falls off, if the green powder does fall off, it is bronze disease. If it is in fact bronze disease I think because it is not so severe you should remove the green powder as much as you can with a soft brush and afterwards leave the coin for 2 weeks in distilled water and change the water every few days. But maybe somebody else can correct me because I don't have that much experience with it. Note that if it is bronze disease you should not let the coin touch any other coins and also that soft brush you used to remove the powder should be washed thoroughly as well. If no green powder falls off when touching with a toothpick I think you should not worry about it.
