Help Identifying A Stamp

I am hoping that someone out there can help by telling me if the attached is indeed a stamp, and if so where from. It's a bit damaged as you can see, and is wrinkled at the bottom right corner, with what looks like the head of Hermes on it. It's in a collection that was passed on to me as a child more than 50 years ago and I have no idea of its origin. The size is about 2cm x 2.5 cm, and the colour a sort of deep plum.

Any help appreciated.

Austrian Mercury Newspaper Stamp. 1867 design

Thanks Maiden for the swift reply.

Specifically this is the 1876 issue of this stamp. A Type III, the outer white ring of the circle around Mercury is open at the top, whereas the other two types are closed.
Scott number P9B.

Thank you JamesW. This website is full of information. I'm glad I came across it.