Tannu Tuva, 10 kopeks. It is a part of Siberia (in Russian Federation). Rare and expensive coin. Not less than 80 dollars.
Yes, Tannu Tuva. I have had this one and a couple of other Tuva coins for over thirty years. They were probably more difficult to "find" before the internet age, but were not too costly for my limited budget at the time. I probably paid about 80 for all three.
I know the country! (But I cheated by consulting our friends at Google). So I won't post the answer unless no one else does before 6 hours from now!
This is a great thread. My guess, either Poland or East Germany. For some reason it gives off a communist vibe.