I suspect that it is bismuth based on the BI stamp at the top and some images I have seen of the mineral online. BI is the periodical symbol for that element and could have been produced from the trepca mines according to the wikipedia link w130sn posted above.
Yep! After a bit more research and answers, I figured out it is Bismuth. Thanks to all of you who helped!
It has a solid price so I'll most likely sell it since I have a few of these bars now. I guess I got lucky with it!