I use very old and fossil bone often. I have used 25 million year old whale vertebrae and rib bones, dinosaur bone, ancient walrus ,Steller's sea cow, and a good bit of mammoth bone. It works like a hard wood, and makes excellent Use fresh belts and avoid heat build up. If the material is completely mineralized, and truly petrified, it takes a bit more work to use it.
Redrum,a maker on this forum, uses a lot of this type of material, so you could ask him for any special advice.
Stacy