What is this?

Question

My mother has had this for as long as I have been alive. 

She got it at an auction in a box of junk.  What is it? I do know whatever it is- is heavy and natural. 

Any ideas?

Answer 1

Looks to me like a piece of glass slag.

Answer 2

It appears to be glass slag.  Leftover from a glass plant that made bottles or other items.  These are often collected because of their bright colors.  There is no real value except for sentimental value by the owner.