Could this be satin glass? It’s marked G Henn but hard to believe that’s the case. This piece is thin and light. It sounds like a twangy bell when I rap on side using my knuckle, It almost sounds like metal.

I’m interested in removing the G Henn. It looks like pencil but when I rub it, it doesn’t come off. Can’t research how to clean it if I don’t know what material it is.