Here are a couple of novaculite bifaces I made. I was on a knapping forum back in 2001. We had a Christmas gift exchange and Steve Kirschman drew my name. He and his dad are from AR and own a company that makes sharpening stones from novaculite. Steve is a knapper and sent me slabs cut on a rock saw. He also heated them for me. Novaculite has to be heated very hot to allow it to be knapped.
I think it has to go to 750°F.