I'm not sure. My dad collected onyx and I also have a domino set made of it. It may be marble, and if it has ever been used, it's been a very long time go. It looks unused to me. The inside is in excellent shape with no marks or holes.
I don't know how to change the settings this is my first time on this site. I don't mind shipping it to you at my cost. My dad had it for years and I kind of inherited it. It may be marble but I thought it was onyx since I also have a set of onyx dominoes.