Old silver coin found in Brandenburg Germany - Letters "Gir"?? [gelöst]

Hi everyone
I found this old (silver?) coin in Brandenburg when metaldetecting near a field. I can't figure out what it is but I don't think it's german? 

I can clearly see the letters “Gir”…

And under “br…” something… Any ideas?

Not silver at all…

N#2729

THANK YOU! That's for sure it!

From the weight alone (that you should have posted together with the diameter when you read the forum rules) you should have guessed that it can not be silver.

 N#2729 

Idolenz

From the weight alone (that you should have posted together with the diameter when you read the forum rules) you should have guessed that it can not be silver.

 

 N#2729 

Why?  https://en.numista.com/catalogue/index.php?r=&st=1-2-3&cat=y&im1=&im2=&ru=&ie=&ca=3&no=&v=&cu=&a=&dg=&i=&b=&m=1&f=&t=23&t2=&w=1.65&mt=&u=&g=&c=&wi=&sw=