Tomahawk /hatchet made of ???????

This was given to me by my grandmother and I was told old native of some sort.It feels like stone or petrified wood maybe it’s smooth and cold. Not sure of the material and seeking some info or insight. Anything is better than what I know thank you I advance as any info is appreciated.

We get a lot of Zuni fetishes carved from onyx which can have this banded look. Not sure if it is made for anything more than the design.