Silver..cannot be rust. Acetone soak & rinse?
It was in contact with something containing iron and the rust stained your coin. These stains can be hard to remove. Maybe acetone will remove some but I wouldn't give it much hope. Best thing to do is forget it and move on IMO
Strictly a melt bucket coin. Don't waste your time on it.
Maybe this was with all those corroded cents someone else posted recently.
Metal detecting find? Based on what I've personally experienced, what @Oldhoopster provided is spot on (pardon the pun).
Yep... It can be restored, but a lot of work and not really of any collector value. Spot silver.... Cheers, RickO
Not of much value but a good project coin for acetone.
As good as it get's.
Looks much better.