I think knappers bake novaculite before they use it.Curious what vitrification temperatures would do to the crystalline structure of novaculite?
Looked back at honing and grinding part 3. The stone they experiment on is Burnt Eidsborg. They use temperatures starting at 400C~750F to 1100C~2000F. They only comment on the hardness of the stone after heating not any other properties. Doubt i will be going to 1100C because, as @musicman980 pointed out, they can explode at high temperatures. I would prefer not to find out at what temperature Pennsylvania blue stone explodes.