My Great Grandmother's Lamp

I love old things and when my great grandmother died I found this in the back of her old tool shed. I had never seen it before and have no history
on it. I don't seem to be able to find anything like it everywhere I search. It is made out of a material that is kind of opalescent when you look at it in the light. It's beautiful and I love it....Just wish I knew more about it.