It is, or at least it's supposed to be, a coin of Ivan Ivanovich of Tver (1485-1490).
A weight of 3.1 grams sounds ridiculously huge though (as far as I can tell, it should be close to 1.5). And it looks far too well preserved as well. So gxseries is probably correct that it's a modern fake/replica. More expert opinion might be needed
