Antique German Hat Pin

I was given this pendant from a friend of mine. It was supposed to be from his grandfather in Germany. I think he mentioned that it was of some military affiliation. It would have to be from before WWII. It looks to me like it's brass or copper maybe. The rim looks like green enamal of some kind. I love the look and wear it on my coat all the time. The animal on it is some sort of elk or deer. I would imagine that it's some animal from Germany. The rim and background are very thin.

I would love to know more about this pendant. If anyone knows anything about it please let me know. I love this pin and I'm always getting comments about it.

Thank You,
Kathy