Obsidian.... everyones favorite point material. You couldn't convince me it make a point. I cant pressure flake it, or precussion. With pressure flaking, i get short flakes. With percussion, i get crumbly dusty mess. I abrade fyi. I cant get the stuff to shoot flakes. It may make a flake, but steps and hinges.
I can knapp glass, and some rock sometimes, and milk glass is my favorite as well as jadite. Obsidian, it doesnt make a point. Not for me.