Are these blade cores?

[Bazo]

Those are cool dustoffer, thanks for sharing

[muzzlebrake]

Nice hammer stones.
I use them myself when working down Obsidian boulders to get spawls for knapping points. I like the granite ones best because they give a good bite. I have about 8 different sizes that I have picked up in river beds. They were just rocks until I started beating on flint with them.