Unknown coin...

Hey guys...I am hoping some of you who are schooled in the old European coins might tell me what this is--before I get out the S.O.S. pads and polish 'er up ;-)

Found this at an antique store...bought it for five bucks. Lady said she had no idea what it was. It appears to be silver, but I haven't done any intrusive testing on it.



And the other side...


Any hints much appreciated.
Thanks!
Dave