The felt crumbles at a touch, so i guess that is what it is. I cant see black marks when looking at the actual coins. Could you point out the marks that concern you and i will take a closer look. Now that i know what i am looking for i will keep an eye on adverts and auctions. I will probably end up listing them on ebay... as much as i hate ebay! Thanks for taking the time to help... much appreciated. Especially on the reverses , some coins have what looks like faint black (or dark blue?) lines, very thin, like pencil marks They were bits of felt. I will take some better pictures when i list them.